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Three cases of unusual lymphoid infiltrate forming nodular macroscopic masses in the liver were studied in the authors' surgical pathology laboratory. These lesions posed difficulty in diagnosis, and their differentiation from low-grade lymphoma was not possible on histopathologic evaluation alone. The liver masses were analyzed histologically and immunohistochemically as well as for clonal immunoglobulin heavy chain (IgH) and T-cell receptor gamma (TCR-gamma) gene rearrangements. The lesions were seen as solitary grossly distinct firm nodules in all three patients, measuring 0.4, 0.7, and 1.5 cm, respectively, in their greatest dimensions. Two were found in livers removed because of end-stage primary biliary cirrhosis at the time of orthotopic liver transplantation, and the third was an incidental finding during laparotomy. Microscopically, these were nodules composed of small lymphocytes, plasma cells, and immunoblasts, with varying degrees of admixed acute inflammatory cells and scattered lymphoid follicles. By immunohistochemistry and molecular studies, these were found to be reactive lymphoid proliferations. All patients are alive and well at 2, 4, and 13 years, respectively. It is concluded that these cases represent a unique type of nodular lymphoid lesion, which is probably an immune-mediated benign reactive hyperplasia. It constitutes an entity by itself and must be distinguished from low-grade lymphoma. For a definitive diagnosis, immunohistochemistry and molecular studies are required.

Whether Kaposi’s sarcoma herpesvirus (KSHV) is associated with multiple myeloma (MM) remains controversial. We assayed for KSHV DNA sequences in long-term bone marrow stromal cells (BMSCs) from 26 patients with MM and 4 normal donors. Polymerase chain reaction (PCR) using primers which amplify a KSHV gene sequence to yield a 233-bp fragment (KS330233 within open reading frame 26) was negative in all cases. Aliquots of these PCR products were used as templates in subsequent nested PCR, with primers that amplify a 186-bp product internal to KS330233. BMSCs from 24 of 26 (92%) patients with MM and 1 of 4 normal donors were KSHV PCR+. DNA sequence analyses showed interpatient specific mutations (2 to 3 bp). Both Southern blot and sequence analyses confirmed the specificity of PCR results. The presence of the KSHV gene sequences was further confirmed by amplifying T 1.1 (open reading frame [ORF] K7) and viral cyclin D (ORF 72), two other domains within the KSHV genome. Immunohistochemical studies of KSHV PCR+ MM BMSCs demonstrate expression of dendritic cell (DC) lineage markers (CD68, CD83, and fascin). Serological studies for the presence of KSHV lytic or latent antibodies were performed using sera from 53 MM patients, 12 normal donors, and 5 human immunodeficiency virus (HIV)/KSHV+ patients. No lytic or latent antibodies were present in sera from either MM patients or normal donors. Taken together, these findings show that KSHV DNA sequences are detectable in BMSCs from the majority of MM patients, but that serologic responses to KSHV are not present. Ongoing studies are defining whether the lack of antibody response is caused by the absence of ongoing infection, the presence of a novel viral strain associated with MM, or underlying immunodeficiency in these patients.

Whether Kaposi’s sarcoma herpesvirus (KSHV) is associated with multiple myeloma (MM) remains controversial. We assayed for KSHV DNA sequences in long-term bone marrow stromal cells (BMSCs) from 26 patients with MM and 4 normal donors. Polymerase chain reaction (PCR) using primers which amplify a KSHV gene sequence to yield a 233-bp fragment (KS330233 within open reading frame 26) was negative in all cases. Aliquots of these PCR products were used as templates in subsequent nested PCR, with primers that amplify a 186-bp product internal to KS330233. BMSCs from 24 of 26 (92%) patients with MM and 1 of 4 normal donors were KSHV PCR+. DNA sequence analyses showed interpatient specific mutations (2 to 3 bp). Both Southern blot and sequence analyses confirmed the specificity of PCR results. The presence of the KSHV gene sequences was further confirmed by amplifying T 1.1 (open reading frame [ORF] K7) and viral cyclin D (ORF 72), two other domains within the KSHV genome. Immunohistochemical studies of KSHV PCR+ MM BMSCs demonstrate expression of dendritic cell (DC) lineage markers (CD68, CD83, and fascin). Serological studies for the presence of KSHV lytic or latent antibodies were performed using sera from 53 MM patients, 12 normal donors, and 5 human immunodeficiency virus (HIV)/KSHV+ patients. No lytic or latent antibodies were present in sera from either MM patients or normal donors. Taken together, these findings show that KSHV DNA sequences are detectable in BMSCs from the majority of MM patients, but that serologic responses to KSHV are not present. Ongoing studies are defining whether the lack of antibody response is caused by the absence of ongoing infection, the presence of a novel viral strain associated with MM, or underlying immunodeficiency in these patients.

We have recently demonstrated the presence of Kaposi's sarcoma–associated herpesvirus (KSHV) in cultured bone marrow (BM) stromal dendritic cells from all patients with myeloma studied. To show that these findings were not an artifact of tissue culture, we performed in situ hybridization (ISH) and polymerase chain reaction (PCR) to detect KSHV in BM core biopsies. Using ISH to open reading frame-72 (ORF 72), we localized KSHV to BM dendritic cells in 17 of 20 patients with myeloma, 2 patients with plasmacytosis associated with the acquired immunodeficiency syndrome, and 1 case of aplastic anemia. In contrast, BM from normal subjects (n = 4) and patients with lymphoma and leukemia (n = 21) did not contain KSHV. PCR amplification with KSHV primers demonstrated product in fresh BM biopsy samples from 6 of 7 myeloma patients, whereas three normal marrows contained no amplified product. These findings suggest that KSHV, possibly through alterations in the BM microenvironment and production of viral interleukin-6 (vIL-6), may stimulate and maintain abnormal plasma cell proliferation in myeloma and related disorders.

Expression of B7 family costimulatory molecules on B cells defines their capacity to function as antigen presenting cells (APCs). B cells that do not express B7 costimulatory molecules induce T-cell tolerance. Therefore, the expression of B7 costimulatory molecules on malignant B cells might be critical for their recognition by anti–tumor-specific T cells. Here we show that virtually all germinal center (GC)-derived B-cell lymphomas including follicular lymphoma (FL) and diffuse large cell lymphoma, but not mantle cell lymphoma or small lymphocytic lymphomas (SLL/CLL), express B7-1 (CD80) and B7-2 (CD86) on their cell surface in situ, although at extremely low levels. Despite their expression of low levels of B7-1 and B7-2, FL cells could not induce significant allogeneic T-cell proliferation. However, B7 costimulatory molecules on FL appeared to be functional because they were capable of increasing T-cell proliferation of preactivated T cells in a secondary allogeneic mixed lymphocyte response. Moreover, low B7 expression was sufficient to prevent the induction of alloantigen-specific anergy in vitro. Therefore, we postulate that whereas low-level expression of B7 is not sufficient to initiate a productive antilymphoma T-cell response, it might be sufficient to prevent T-cell tolerance in vivo.

Prior in vitro studies have suggested a role of adhesion molecules, bone marrow stromal cells (BMSCs), and cytokines in the regulation of human multiple myeloma (MM) cell growth and survival. Although in vivo models have been developed in severe combined immunodeficient (SCID) mice that support the growth of human MM within the murine BM microenvironment, these xenograft models do not permit a study of the role of adhesion proteins in human MM cell-human BMSC interactions. We therefore established an in vivo model of human MM using SCID mice implanted with bilateral human fetal bone grafts (SCID-hu mice). For the initial tumor innoculum, human MM derived cell lines (1 × 104 or 5 × 104 ARH-77, OCI-My5, U-266, or RPMI-8226 cells) were injected directly into the BM cavity of the left bone implants in irradiated SCID-hu mice. MM cells engrafted and proliferated in the left human fetal bone implants within SCID-hu mice as early as 4 weeks after injection of as few as 1 × 104 MM cells. To determine whether homing of tumor cells occurred, animals were observed for up to 12 weeks after injection and killed to examine for tumor in the right bone implants. Of great interest, metastases to the right bone implants were observed at 12 weeks after the injection of 5 × 104 MM cells, without spread of human MM cells to murine BM. Human MM cells were identified on the basis of characteristic histology and monoclonal human Ig. Importantly, monoclonal human Ig and human interleukin-6 (IL-6), but not human IL-1β or tumor necrosis factor-α, were detectable in sera of SCID-hu mice injected with MM cells. In addition, specific monoclonal Ig light chain deposition was evident within renal tubules. This in vivo model of human MM provides for the first time a means for identifying adhesion molecules that are responsible for specific homing of human MM cells to the human, as opposed to murine, BM microenvironment. Moreover, induction of human IL-6 suggests the possibility that regulation of MM cell growth by this cytokine might also be investigated using this in vivo model.

Amniotic fluid bacterial infection is an occasional cause of second trimester septic abortion. We describe an autolysis-related histological artifact, umbilical cord 'pseudo-vasculitis', which can erroneously implicate amniotic bacterial infection in fetal death. Clinicopathological features of 13 second trimester fetal deaths with umbilical cord pseudo-vasculitis are reported. In four cases (31%), an incorrect pathological diagnosis of umbilical vasculitis had initially been rendered. Umbilical cords from five cases of pseudo-vasculitis and one comparison fetus (18-week septic abortion with true umbilical vasculitis), were studied with chloroacetate esterase and with immunohistochemical staining for myeloperoxidase, muscle-specific actin (HHF35) and smooth muscle actin. Histologically, umbilical pseudo-vasculitis exhibited numerous small, rounded, degenerating cells with irregular, multilobed nuclei (closely resembling neutrophils) located within the umbilical vessel wall. Immunohistochemical studies demonstrated that all cells resembling neutrophils were of smooth muscle origin. Moderate to severe fetal autolysis was present in all cases of umbilical pseudo-vasculitis, suggesting that this finding represents autolysis of umbilical vascular smooth muscle secondary to post moderate fetal retention. Vascular smooth muscle in other fetal and placental locations did not demonstrate the finding, suggesting that this striking degenerative artifact of smooth muscle is restricted to the umbilical cord.

T-cell blast crisis in chronic myelogenous leukemia is rare. We examined three patients (ages 35 to 72 years) in whom T-cell blast crisis developed 11 to 36 months (mean, 25 months) after diagnosis of chronic myelogenous leukemia and who died 4 to 12 months (mean, 7 months) thereafter. Two patients had diffuse lymphadenopathy, and the third had marked lymphocytosis (white blood cell count 217,000/microL, with 90% circulating blasts). In all three patients, neoplastic cells had the appearance of lymphoblasts and were immunoreactive for T-cell markers by immunohistochemical or flow cytometric analysis or both. Molecular diagnostic studies revealed the presence of a bcr-abl oncogene rearrangement in all three cases, but none exhibited a clonal T-cell receptor delta, beta, or gamma chain gene rearrangement. One case exhibited deletion of the J delta 1 region of both delta chain genes. The significance of these findings is discussed, and they are compared with those of other reported cases of T-cell blast crisis in chronic myelogenous leukemia.

Adenocarcinoma can be challenging to distinguish from malignant mesothelioma in effusions, and this distinction often requires ancillary studies and clinical correlation. Immunohistochemistry for claudin-4, a tight-junction-associated protein, has recently been shown to distinguish adenocarcinoma from malignant mesothelioma, mostly in surgical specimens. Our aim was to validate and assess the immunoreactivity profile of claudin-4 in a large series of malignant effusions.We evaluated 159 malignant effusions (84 adenocarcinomas and 75 malignant mesotheliomas). Claudin-4 immunohistochemistry was performed on cell-block paraffin sections and scored for staining intensity, staining pattern (cytoplasmic versus membranous), and percentage of positive tumor cells. Appropriate positive and negative controls were used throughout.All cases of mesothelioma were negative for claudin-4 (0 of 64). Eighty-three of 84 cases of adenocarcinoma were positive (99%); 1 case of serous carcinoma was negative. Most adenocarcinomas showed strong and diffuse membranous staining (71 of 84; 84%); 12 cases (14%) showed membranous staining of moderate intensity. The overall sensitivity for adenocarcinoma was 99% (83 of 84).Claudin-4 immunohistochemistry effectively distinguishes adenocarcinoma from malignant mesothelioma with high sensitivity and specificity in the evaluation of malignant effusions.

Detection of the integrin subunit CD103 is a useful diagnostic tool in the diagnosis of hairy cell leukemia (HCL). Currently, flow cytometric analysis (FC) and frozen section immunohistochemistry (IHC) represent the only available methods of detection. This study is the first to describe the successful use of a CD103 antibody to identify HCL and HCL-variant in paraffin sections of formalin- or Bouin solution– fixed specimens (n = 68) using an immunoperoxidase technique. In other B-cell lymphoproliferative disorders that morphologically may resemble HCL, including chronic lymphocytic leukemia/small lymphocytic lymphoma (n = 32), mantle cell lymphoma (n = 23), lymphoplasmacytic lymphoma (n = 27), follicular lymphoma (n = 7), and marginal zone lymphoma (n = 13), lymphoid cells are nonreactive for CD103. In HCL, the CD103 staining pattern is predominantly membranous with delineation of delicate cytoplasmic projections. This CD103 antibody is an extremely valuable addition to the IHC panel for the diagnosis of HCL, especially in cases lacking FC analysis.

Fixed, paraffin-embedded (FPE) tissues are a potentially rich resource for studying the role of NOTCH1 in cancer and other pathologies, but tests that reliably detect activated NOTCH1 (NICD1) in FPE samples have been lacking. Here, we bridge this gap by developing an immunohistochemical (IHC) stain that detects a neoepitope created by the proteolytic cleavage event that activates NOTCH1. Following validation using xenografted cancers and normal tissues with known patterns of NOTCH1 activation, we applied this test to tumors linked to dysregulated Notch signaling by mutational studies. As expected, frequent NICD1 staining was observed in T lymphoblastic leukemia/lymphoma, a tumor in which activating NOTCH1 mutations are common. However, when IHC was used to gauge NOTCH1 activation in other human cancers, several unexpected findings emerged. Among B cell tumors, NICD1 staining was much more frequent in chronic lymphocytic leukemia than would be predicted based on the frequency of NOTCH1 mutations, while mantle cell lymphoma and diffuse large B cell lymphoma showed no evidence of NOTCH1 activation. NICD1 was also detected in 38% of peripheral T cell lymphomas. Of interest, NICD1 staining in chronic lymphocytic leukemia cells and in angioimmunoblastic lymphoma was consistently more pronounced in lymph nodes than in surrounding soft tissues, implicating factors in the nodal microenvironment in NOTCH1 activation in these diseases. Among carcinomas, diffuse strong NICD1 staining was observed in 3.8% of cases of triple negative breast cancer (3 of 78 tumors), but was absent from 151 non-small cell lung carcinomas and 147 ovarian carcinomas. Frequent staining of normal endothelium was also observed; in line with this observation, strong NICD1 staining was also seen in 77% of angiosarcomas. These findings complement insights from genomic sequencing studies and suggest that IHC staining is a valuable experimental tool that may be useful in selection of patients for clinical trials.

Lymphomas arising primarily in serosal surfaces have recently been described. Although these "body-cavity" lymphomas usually present as an effusion, the role of cytologic diagnosis has not been fully explored. The authors present seven cases of primary serous lymphoma. All were large cell lymphomas (5 B cell types, 2 T cell types). Three distinct clinical presentations were seen. Four patients had the rapid onset of pleural effusions without an associated mass in the setting of immunodeficiency (3 with AIDS, 1 with Castleman's disease). Cytologic examination of the effusion was positive in all cases for B-cell lymphoma. All four patients died of their disease in less than 6 months. Two other patients with AIDS and T-cell lymphomas both of which were associated with a serosal mass as well as an effusion. Although cytologic examination revealed numerous atypical lymphoid cells, clonality could not be demonstrated. One patient survived for more than 1 year, the other lymphoma was an incidental finding at autopsy. Finally, one B-cell lymphoma arose in a patient with chronic pleuritis. Pleural decortication was required to identify the neoplastic cells. The authors conclude that primary serosal lymphomas have characteristic clinical presentations, and that although cytologic and flow cytometric examination of effusions is necessary for the diagnosis of immunodeficiency associated B-cell lymphomas, tissue biopsy will likely be required in patients with immunodeficiency-associated T-cell lymphomas or lymphomas associated with chronic pleuritis.

MicroRNA (miR)-mediated gene regulation plays critical roles in B-cell development and dysregulated expression of miRs has been implicated in the pathogenesis of various types of B-cell malignancies. Somatic deletions of chromosome 13q14, harboring miR-15a/16-1, occurs frequently in B-cell lymphomas suggesting that members of this miR family are tumor suppressors. Consistently, mice with CD19-Cre-induced deletion of miR-15a/16-1 in early B-cells and follicular B-cells develop chronic lymphocytic leukemia (CLL). Since the 13q14 deletion is observed in a broader range of B-cell malignancies, we hypothesized that the type of B-cell malignancy resulting from miR-15a/16-1 down-regulation may depend on the stage of B-cell development at which this deletion occurs. Therefore, we generated a transgenic mouse model in which conditional deletion of miR-15a/16-1 takes place at later stages of B-cell development. To delete miR-15a/16-1 in activated B-cells, miR-15a/16-1fl/fl mice were mated with AID-Cre+/+ mice to obtain AID-Cre+/-; miR-15a/16-1fl/fl compound mice that expressed Cre recombinase from the Activation-induced Cytidine Deaminase (AID promoter) gene - a gene needed for generation of somatic hypermutations in the immunoglobulin (Ig) variable region (V) genes that is highly expressed in activated B-cells and is a well-known marker for germinal center (GC) B-cells. Expression levels of both miR-15a and miR-16-1, but not miR-15b were decreased in GC B-cells of AID-Cre+/-; miR-15a/16-1fl/fl mice as compared with control AID-Cre+/- mice when evaluated by In Situ Hybridization (ISH) analysis. Given that in humans miR-15a, b and 16 are also expressed in GC B-cells, these results demonstrate the validity of this mouse model in which the biological consequences of miR-15a/16-1 deletion can be studied. Next we assessed whether miR-15a/16-1 deletion could affect proliferation and/or survival of GC B-cells. GCs in the spleens of AID-Cre+/-; miR-15a/16-1fl/fl mice at 10 weeks of age were significantly increased in both number and size, and contained a larger number of Ki-67-positive B-cells as compared with spleens of AID-Cre+/- mice. No significant differences in the number of apoptotic cells, neither in the expression of the miR-15a/16-1 putative target BCL2 were detected, indicating that miR-15a/16-1 may play important roles in the proliferation, but not survival of GC B-cells. Apart from mild splenic enlargement and increased number and size of GCs, AID-Cre+/-, miR-15a/16-1fl/fl mice where indistinguishable from AID-Cre+/- mice between 8 and 40 weeks of age as assessed by weight and posture. However, after 48 weeks of age and at variable times thereafter, 80% (32/40) of AID-Cre+/-, miR-15a/16-1fl/fl mice but none from control cohorts (0/30) showed signs of disease. Gross pathologic examination of euthanized AID-Cre+/-; miR-15a/16-1fl/fl mice revealed enlargement of the spleen and lymph nodes. Detailed histological examination revealed in most instances an effacement of normal tissue architecture by a nodular or diffuse population of atypical lymphoid cells, or less commonly by sheets of plasma cells in interfollicular areas. Two distinct patterns of B220+BCL6+BCL2- B-cell lymphomas were identified after detailed analysis. The most common (47%) resembled human follicular lymphoma (FL) and the next in frequency (28%) resembled human diffuse large B-cell lymphoma (DLBCL). The other group of tumors (25%) resembled human plasmacytoma (PC). All three tumor subtypes were clonal, hypermutated and associated with different degrees of preservation of the dendritic meshwork in the lymph nodes. The comparison of lymphomas arising in AID-Cre+/-; miR-15a/16-1fl/fl mice and CD19-Cre+/-; miR-15a/16-1fl/fl mice corroborated that deletion of miR-15a/16-1 at different stages of B-cell development leads to distinct subtypes of B-cell malignancies. Finally, we investigated miR-15a/16-1 expression in human FL and PC and showed that miR-15a/16-1 abundance is significantly decreased in those malignancies when compared with nodal B-cells in reactive GCs and normal plasma cells in interfollicular areas respectively, suggesting that miR-15a/16-1 may play important roles in normal GC B-cell development as well as in the pathogenesis of FL and PC in humans. Disclosures Ghobrial: BMS: Honoraria, Research Funding; Novartis: Honoraria; Celgene: Honoraria, Research Funding; Takeda: Honoraria; Noxxon: Honoraria; Amgen: Honoraria. Anderson:Oncoprep: Equity Ownership; Acetylon: Equity Ownership; Oncoprep: Equity Ownership; Gilead: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Acetylon: Equity Ownership; Millennuim: Membership on an entity's Board of Directors or advisory committees; Millennuim: Membership on an entity's Board of Directors or advisory committees; C4 Therapeutics: Equity Ownership; C4 Therapeutics: Equity Ownership; Bristol Myers Squibb: Membership on an entity's Board of Directors or advisory committees; Bristol Myers Squibb: Membership on an entity's Board of Directors or advisory committees.

Objective. Therapeutic trials in rheumatoid arthritis with the monoclonal antibody Campath-1H have demonstrated recurrent clinical synovitis in some patients, despite profound depletion of circulating lymphocytes. This study was undertaken to examine the cellular infiltrates in synovial tissue at a time of persistent peripheral lymphopenia. Methods. Immunohistochemical staining of synovial tissue and peripheral blood lymphocyte phenotyping. Results. Synovial tissues from 2 patients with recurrent synovitis after Campath-1H therapy contained significant T lymphocytic infiltrates at a time when circulating T lymphocytes were markedly depleted. Conclusion. These results demonstrate that peripheral blood analysis may not accurately reflect the synovial tissue response to monoclonal antibody therapy.

A b s t r ac t Background Waldenstrom’s macroglobulinemia is an incurable, IgM-secreting lymphoplasmacytic lymphoma (LPL). The underlying mutation in this disorder has not been delineated. Methods We performed whole-genome sequencing of bone marrow LPL cells in 30 patients with Waldenstrom’s macroglobulinemia, with paired normal-tissue and tumor-tissue sequencing in 10 patients. Sanger sequencing was used to validate the findings in samples from an expanded cohort of patients with LPL, those with other B-cell disorders that have some of the same features as LPL, and healthy donors. Results Among the patients with Waldenstrom’s macroglobulinemia, a somatic variant (T→C) in LPL cells was identified at position 38182641 at 3p22.2 in the samples from all 10 patients with paired tissue samples and in 17 of 20 samples from patients with unpaired samples. This variant predicted an amino acid change (L265P) in MYD88, a mutation that triggers IRAK-mediated NF-κB signaling. Sanger sequencing identified MYD88 L265P in tumor samples from 49 of 54 patients with Waldenstrom’s macroglobulinemia and in 3 of 3 patients with non–IgM-secreting LPL (91% of all patients with LPL). MYD88 L265P was absent in paired normal tissue samples from patients with Waldenstrom’s macroglobulinemia or non-IgM LPL and in B cells from healthy donors and was absent or rarely expressed in samples from patients with multiple myeloma, marginal-zone lymphoma, or IgM monoclonal gammopathy of unknown significance. Inhibition of MYD88 signaling reduced IκBα and NF-κB p65 phosphorylation, as well as NF-κB nuclear staining, in Waldenstrom’s macroglobulinemia cells expressing MYD88 L265P. Somatic variants in ARID1A in 5 of 30 patients (17%), leading to a premature stop or frameshift, were also identified and were associated with an increased disease burden. In addition, 2 of 3 patients with Waldenstrom’s macroglobulinemia who had wild-type MYD88 had somatic variants in MLL2. Conclusions MYD88 L265P is a commonly recurring mutation in patients with Waldenstrom’s macroglobulinemia that can be useful in differentiating Waldenstrom’s macroglobulinemia and non-IgM LPL from B-cell disorders that have some of the same features. (Funded by the Peter and Helen Bing Foundation and others.)

Pediatric follicular lymphoma (PFL) is a variant of follicular lymphoma (FL) presenting as localized lymphadenopathy in children. Unlike conventional adult FL, PFL typically does not recur or progress. Clear diagnostic criteria for PFL are lacking, and it is uncertain whether this indolent lymphoma is defined by age or may occur in adults. We analyzed 27 FL in patients < 40 years of age and found that all 21 cases that lacked a BCL2 gene abnormality (BCL2-N; P < .0001) and had > 30% Ki67 fraction (high proliferation index, HPI; P = .0007) were stage I and did not progress or recur; in comparison, all 6 cases with BCL2 rearrangement and/or PI < 30% were stage III/IV, and 5 of 6 recurred or progressed. In a separate cohort of 58 adult FL (≥ 18 years of age), all 13 BCL2-N/HPI cases were stage I, and none progressed or relapsed, whereas 11 of 15 stage I cases with BCL2 gene abnormality and/or LPI relapsed or progressed (P = .0001). The adult and pediatric BCL2-N/HPI FL cases had similar morphologic features. Our results confirm the highly indolent behavior of PFL and suggest that these are characterized by HPI and absence of BCL2 gene abnormality. PFL-like cases also occur in adults and are associated with indolent behavior in this patient population.

Background/Aims: Human basic fibroblast growth factor (bFGF) is an endothelial mitogen that stimulates angiogenesis and proliferation of other cells such as fibroblasts and smooth muscle cells. After this peptide was stabilized to acid and pepsin by site-specific mutagenesis, it was tested whether bFGF might accelerate the healing of experimental duodenal ulcers. Methods: This mutein peptide (bFGF-CS23) was administered orally in comparison with cimetidine to rats with chronic duodenal ulcers previously induced by cysteamine. Results: Oral bFGF-CS23 therapy maintained for 21 days at 100 ng/100 g twice daily resulted in (1) significant acceleration of healing of duodenal ulcers, i.e., reduction of mean ulcer area by 83% in the bFGF-CS23-treated rats compared with only 61% for cimetidine therapy and 40% for untreated controls; (2) complete healing with no residual ulcer in 62% of the bFGF-CS23-treated rats compared with only 7% of untreated rats; and (3) a ninefold increase in angiogenesis in the ulcer bed compared with untreated controls. A single dose of the bFGF-CS23 mutein had no effect on gastric output of hydrochloric acid or pepsin, but daily treatment for 2 or 3 weeks resulted in enhanced acid and pepsin outputs. Conclusions: Chronic duodenal ulcers can be healed rapidly by stimulating angiogenesis and other wound-healing processes in the ulcer bed without reduction of gastric acid.

Diffuse large B cell lymphoma (DLBCL) is a clinically and genetically heterogeneous disease. A small subset of DLBCLs has translocations involving the MYC locus and an additional group has a molecular signature resembling Burkitt lymphoma (mBL). Presently, identification of such cases by morphology is unreliable and relies on cytogenetic or complex molecular methods such as gene transcriptional profiling. Herein, we describe an immunohistochemical (IHC) method for identifying DLBCLs with increased MYC protein expression. We tested 77 cases of DLBCL and identified 15 cases with high MYC protein expression (nuclear staining in >50% of tumor cells). All MYC translocation positive cases had increased MYC protein expression by this IHC assay. In addition, gene set enrichment analysis (GSEA) of the DLBCL transcriptional profiles revealed that tumors with increased MYC protein expression (regardless of underlying MYC translocation status) had coordinate upregulation of MYC target genes, providing molecular confirmation of the IHC results. We then generated a molecular classifier derived from the MYC IHC results in our cases and employed it to successfully classify mBLs from two previously reported independent case series, providing additional confirmation that the MYC IHC results identify clinically important subsets of DLBCLs. Lastly, we found that DLBCLs with high MYC protein expression had inferior overall survival when treated with R-CHOP. In conclusion, the IHC method described herein can be used to readily identify the biologically and clinically distinct cases of MYC-driven DLBCL, which represent a clinically significant subset of DLBCL cases due to their inferior overall survival.

Twenty patients with poor prognosis B-cell chronic lymphocytic leukemia (B-CLL) underwent uniform high-dose chemoradiotherapy followed by rescue with multiple monoclonal antibody-purged autologous bone marrow (BM) (12 patients) or T-cell-depleted allogeneic BM from HLA-identical siblings (8 patients) in a pilot study to assess the feasibility of BM transplantation (BMT) in this disease. All had poor prognosis disease by either staging, BM pattern, tumor doubling time criteria, or cytogenetics. All patients achieved remission criteria (defined as < or = 2 adenopathy, absence of splenomegaly, < or = 20% of the intertrabecular space involved on BM biopsy) before BMT. Despite the use of fludarabine, a median of three treatment regimens were required to achieve BMT eligibility. After BMT, all patients achieved complete hematologic engraftment. Toxicities were not significantly different between autologous versus allogeneic BMT. Two toxic deaths were observed. Of 19 evaluable patients, 17 clinical complete clinical remissions (89%) were observed, with 2 patients (1 allogeneic and 1 autologous) exhibiting persistent BM disease. Complete clinical remissions were documented at the phenotypic and molecular level for the majority of patients in whom dual fluorescence for CD5 and CD20 (15 of 15; 100%) and Ig gene rearrangements (11 of 14; 79%) were performed. Although long-term follow-up is needed to assess any potential impact on the disease-free and overall survival of these patients, this study shows the feasibility of using high-dose chemoradiotherapy and BMT in patients with poor prognosis B-CLL.

We describe a clonal chromosome rearrangement, t(4; 14)(q24-25; q24.3), in a benign fibrous tumor of the breast. This is the first reported cytogenetic analysis of a fibrous tumor of the breast and the first evidence for clonality in these lesions. A combined immunohistochemical/cytogenetic study demonstrated that cells with the clonal translocation were mesenchymal. Epithelial cells, in contrast, had normal chromosomes.

Accurate analysis of the erythroid lineage is essential in evaluating bone marrow biopsy specimens and can be particularly challenging in the setting of dyserythropoiesis. Transferrin receptor (CD71) mediates the uptake of transferrin-iron complexes and is highly expressed on the surface of cells of the erythroid lineage. Although CD71 has been used for flow cytometric analysis, its usefulness in paraffin-embedded bone marrow biopsy specimens has not been examined. This study defined the immunohistochemical profile of CD71, as compared with glycophorin A (CD235a) and hemoglobin, in 65 bone marrow biopsy specimens, including normal marrow specimens and cases of myelodysplastic syndrome, acute myeloid leukemia, acute lymphoblastic leukemia, plasma cell neoplasm, and metastatic carcinoma. Immunoreactivity for CD71 was restricted to erythroid precursors in normal and dyspoietic marrow samples and exhibited a membranous and cytoplasmic staining pattern. The vast majority of mature erythrocytes lack expression of CD71, greatly facilitating interpretation. CD71 is a highly effective marker for the detection of cells of erythroid lineage in bone marrow biopsy specimens.

Familial hemophagocytic lymphohistiocytosis is a rare, rapidly progressive disorder characterized by an activation of the immune system resulting in a systemic proliferation of lymphocytes and histiocytes. The disease is genetically heterogeneous and maps to at least 4 loci including the gene encoding perforin, a protein critical for the cytotoxic and regulatory functions of T lymphocytes and natural killer (NK) cells. Hepatic dysfunction often occurs early in the clinical course, but the pathology of the liver is not well characterized. The clinical history, laboratory data, and pathologic material (25 hepatic specimens) from 19 children (11 boys, 7 girls, 1 unknown, 12 d to 11 mo of age, median 3 mo) with FHL were reviewed. Routine and immunohistochemical stains were carried out in all cases, and perforin gene sequencing in a subset. Common to all specimens was a portal and sinusoidal infiltrate of CD3, CD8, granzyme B+ lymphocytes admixed with CD68, CD1a- histiocytes that exhibited hemophagocytosis. There was endothelialitis of portal and central veins and lymphocyte-mediated bile duct injury. The degree of portal and sinusoidal lymphohistiocytic infiltrate and endothelialitis varied from mild to marked and correlated with clinical severity. In some specimens, histiocytic cells predominated and in others, there was extensive hepatocellular giant cell transformation. Accordingly, 4 histopathologic patterns were observed: (1) chronic hepatitis-like, (2) leukemia-like, (3) histiocytic storage disorder-like, and (4) neonatal giant cell hepatitis-like. Two siblings homozygous for a 50delT nucleotide deletion had no perforin immunoreactive cells, 1 compound heterozygote for a deletion and missense mutation had cells with markedly diminished perforin expression, and 1 infant hemizygous for a perforin missense mutation had intact expression. Recognizing the morphologic changes in the liver and the immunophenotypic features of the infiltrate are critical for a rapid diagnosis and a prompt institution of treatment.

Previous cytogenetic analyses revealed t(6;20)(p21;q13) in two endometrial polyps. We karyotyped a large endometrial polyp in which 19 of 25 metaphase cells contained a t(1;6;4)(q21;p21;q13). Subsequent combined immunohistochemical/cytogenetic analysis showed all aberrant metaphase cells to be of mesenchymal derivation, whereas epithelial cells from the polyp were diploid. These studies indicate that rearrangement of chromosome band 6p21 is a characteristic cytogenetic aberration in the stromal component of endometrial polyps.

OBJECTIVE To evaluate the utility of real-time, high-resolution ultrasound of the shoulder in the diagnosis of dialysis-related amyloidosis. METHODS We performed a case series study of 2 groups of patients seen at a referral-based clinic in a tertiary care hospital. The shoulders of 13 patients with normal renal function and of 38 patients receiving long-term hemodialysis were studied by real-time, high-resolution ultrasound. All hemodialysis patients were evaluated clinically for the presence of dialysis-related amyloidosis. Surgical specimens of joints were available for all 13 patients with normal renal function and for 17 of the 38 hemodialysis patients. These specimens were evaluated for the presence of beta 2-microglobulin (beta 2m) amyloid by Congo red and immunohistochemical staining. RESULTS Two ultrasonographic findings were selectively observed in the dialysis patients with clinical and histologic evidence of beta 2m amyloid in comparison with patients with normal renal function and no evidence of amyloid: rotator cuffs greater than 8 mm in thickness and echogenic pads between muscle groups of the rotator cuff. The presence of at least 1 of these 2 findings corresponded to the presence of clinically and histologically evident beta 2m amyloid with a sensitivity of 79% and a specificity of 100%. When additional patients without surgical specimens for histologic confirmation of amyloidosis were included, the sensitivity of these 2 sonographic findings was 72% and the specificity was 97%. CONCLUSION Real-time, high-resolution ultrasound is a relatively sensitive and highly specific noninvasive adjunct to the clinical diagnosis of beta 2m amyloidosis in patients receiving long-term hemodialysis.

Purpose The optimal treatment for early-stage, lymphocyte-predominant Hodgkin's lymphoma (LPHL) is not well defined. Treatment has become less aggressive over time in an attempt to reduce iatrogenic complications, such as cardiac mortality and second cancers, but long-term efficacy is unclear. We present the long-term outcome of patients treated at a single institution. Patients and Methods The study population includes 113 patients with stage I or II LPHL treated between 1970 and 2005. Pathologic diagnosis for all patients was confirmed using standard criteria. Ninety-three patients received radiation therapy (RT) alone, 13 received RT with chemotherapy, and seven received chemotherapy alone. Among patients treated with RT, 25 received limited-field, 35 received regional-field, and 46 received extended-field RT. Results Median follow-up was 136 months. Ten-year progression-free survival (PFS) rates were 85% (stage I) and 61% (stage II); overall survival (OS) rates were 94% and 97% for stages I and II, respectively. PFS and OS did not differ among patients who received limited-field, regional-field, or extended-field RT. In contrast, six of seven patients who received chemotherapy alone without RT developed early disease progression and required salvage treatment. Multivariable analysis adjusting for extent of RT, clinical stage, sex, and use of chemotherapy confirmed that the extent of RT was not significantly associated with PFS (P = .67) or OS (P = .99). The addition of chemotherapy to RT did not improve PFS or OS compared with RT alone. Conclusion RT alone leads to sustained disease control and high long-term survival rates in patients with early-stage LPHL. This study supports the use of limited-field RT alone to treat this disease.

Purpose: To investigate the impact of interferon-γ–mediated upregulation of major histocompatibility complex class I expression on tumor-specific T-cell cytotoxicity and T-cell trafficking into neuroblastoma tumors in vivo.Experimental Design: Restoration of major histocompatibility complex class I expression by interferon-γ treatment enhances killing of neuroblastoma cells. To understand the potential of this approach in vivo, we developed a novel model of neuroblastoma in which NOD/scid/IL2Rγnull immunodeficient mice are engrafted with both human T cells and tumor cells.Results: Here, we show enhanced killing of neuroblastoma cells by patient-derived, tumor-specific T cells in vitro. In addition, interferon-γ treatment in vivo induces efficient upregulation of major histocompatibility complex class I expression on neuroblastoma tumor cells, and this is accompanied by significantly enhanced infiltration of T cells into the tumor. In a pilot clinical trial in patients with high-risk neuroblastoma, we similarly observed augmented T-cell trafficking into neuroblastoma nests in tumor biopsy specimens obtained from patients after 5 days of systemic interferon-γ therapy.Conclusions: Interferon-γ overcomes critical obstacles to the killing of human neuroblastoma cells by specific T cells. Together, these findings provide a rationale for the further testing of interferon-γ as an approach for improving the efficacy of T cell–based therapies for neuroblastoma and other major histocompatibility complex class I–deficient malignancies. In addition, we describe a model that may expedite the preclinical screening of approaches aimed at augmenting T-cell trafficking into human tumors. (Clin Cancer Res 2009;15(21):6602–8)

Dysregulated JAK2 signaling has been shown to play a significant role in the pathogenesis of myeloproliferative disorders. Recently, our work comparing gene expression signatures of primary mediastinal large B-cell lymphomas (PMLBCL) versus nodal diffuse large B-cell lymphomas (DLBCL) revealed a relative increase in JAK2 transcripts in the former suggesting a role for increased JAK2 signaling in a subset of these tumors. Given the likelihood of increased JAK2 signaling in PMLBCL, we sought to determine whether JAK2 activating mutations were an alternative mechanism for increased JAK2 signaling in untreated PMLBCLs. We performed amplification refractory mutation analysis for the JAK2 (V617F) mutation and bi-directional sequencing for the recently described JAK2 exon 12 mutations on genomic DNA isolated from a well characterized cohort of PMLBCLs. No evidence of the mutant JAK2 (V617F) allele or JAK2 exon 12 mutations was detected in 31 PMLBCL cases tested. Analysis using cell lines derived from PMLBCLs (n=1) and from the molecularly similar classical Hodgkin lymphoma (n=4) also failed to reveal involvement of this mutant JAK2 allele. Taken together, these results suggest that JAK2 signaling in PMLBCLs occurs by mechanisms distinct from JAK2 (V617F) or JAK2 exon 12 activating mutations.

Nodular lymphocyte-predominant Hodgkin lymphoma (NLPHL) and lymphocyte-rich classical Hodgkin lymphoma (LRCHL), although clinically and morphologically similar, differ biologically and in prognosis. Immunolabeling of Reed-Sternberg (RS) cells in LRCHL and lymphocytic and/or histiocytic variants (L&H cells) in NLPHL is often required to help distinguish between the 2 variants. Our aim was to evaluate fascin (a distinct 55-kd actin-bundling protein) and JunB (an activator protein-1 family transcription factor) to differentiate NLPHL from LRCHL. A total of 35 archival cases of NLPHL (n = 24) and LRCHL (n = 11) from adults and children were studied. Slides were reviewed for all cases and clinical, morphologic, and immunohistochemical features were evaluated. Each case was immunostained for fascin and JunB, and immunoreactivity of RS cells, L&H cells, and background lymphocytes were recorded. Whereas occasional L&H cells were weakly positive for fascin in 3 out of 24 (12.5%) cases of NLPHL, RS cells in LRCHL were positive for fascin in 11 out of 11 (100%) cases with a strong cytoplasmic staining pattern. JunB was positive in 10 out of 24 (41.7%) of NLPHL cases, and 11 out of 11 (100%) of LRCHL cases, showing a stippled and/or diffuse nuclear staining pattern. In addition to L & H Cells, JunB also stained small background lymphocytes, particularly in areas of progressively transformed germinal centers of NLPHL. Either stains when tested alone, if negative, or with rare L&H cell weak positivity for fascin, is indicative of NLPHL. The L&H cells of NLPHL cases were negative for concomitant staining in 24 out of 24 (100%) cases. Concomitant positive staining of classic RS cells for fascin and JunB was found in 11 out of 11 (100%) of LRCHL cases. Although fascin positivity alone supports the diagnosis of LRCHL, concomitant positivity offers stronger support and is less likely to lead to a false conclusion if aberrant fascin staining were to be encountered in a case of NLPHL. Staining for fascin and JunB provides a basis for distinguishing NLPHL from LRCHL and offers an alternative to other antibody profiles.

We compared the effectiveness of epithelial membrane antigen (EMA) with 2 newly described markers, X-linked inhibitor of apoptosis protein (XIAP) and an isoform of glucose transporter (GLUT-1), in the distinction between malignant mesothelioma (MM) and benign effusion (BE) in body cavity fluids. Immunohistochemical studies were performed on cell block sections from 35 cases of histologically confirmed MM and 38 BEs, using antibodies to EMA, XIAP, GLUT-1 (GLUT-1m, monoclonal; GLUT-1p, polyclonal). Results were graded based on the percentage of cells staining: negative (0%), 1+ (

Germ cell tumors are a heterogeneous group of neoplasms derived from residual primordial tissue. These tumors are commonly found in the brain, testes, or ovaries, where they are termed germinomas, seminomas, or dysgerminomas, respectively. Like several other tumor types, germ cell tumors often harbor an immune cell infiltrate that can include substantial numbers of B cells. Yet little is known about whether the humoral immune response affects germ cell tumor biology. To gain a deeper understanding of the role B cells play in this tumor family, we characterized the immune cell infiltrate of all three germ cell tumor subtypes and defined the molecular characteristics of the B cell Ag receptor expressed by tumor-associated B cells. Immunohistochemistry revealed a prominent B cell infiltrate in the microenvironment of all tumors examined and clear evidence of extranodal lymphoid follicles with germinal center-like architecture in a subset of specimens. Molecular characterization of the Ig variable region from 320 sequences expressed by germ cell tumor-infiltrating B cells revealed clear evidence of Ag experience, in that the cardinal features of an Ag-driven B cell response were present: significant somatic mutation, isotype switching, and codon insertion/deletion. This characterization also revealed the presence of both B cell clonal expansion and variation, suggesting that local B cell maturation most likely occurs within the tumor microenvironment. In contrast, sequences from control tissues and peripheral blood displayed none of these characteristics. Collectively, these data strongly suggest that an adaptive and specific humoral immune response is occurring within the tumor microenvironment.

Histiocytic necrotizing lymphadenitis (HNL) is a rare benign disorder characterized histologically by nodal lesions composed of histiocytes, lymphoid cells, and so-called plasmacytoid T cells/plasmacytoid monocytes, with associated karyorrhexis. It has been proposed that plasmacytoid monocytes represent immature myeloid and lymphoid (plasmacytoid) early-committed dendritic cells (DCs). Monoclonal antibodies are now available for the detection of myeloid (CD1c [BDCA-1]+) and plasmacytoid (CD303 [BDCA-2]+) dendritic cells. With an extensive panel of antibodies to immature and mature DCs and interferon-alpha (IFN-alpha), cryostat section studies of 6 cases of HNL revealed that the morphologically distinctive mononuclear cells in lesional areas consisted of 2 populations of immature DCs: myeloid DCs immunoreactive for CD1c with coexpression of myeloid antigens CD13 and CD33 and plasmacytoid DCs immunoreactive for CD303 and CD123. These cells were CD68+, strongly expressed the IFN-alpha inducible protein MxA, and were nonreactive for fascin, a mature DC marker.

Polymerase chain reaction (PCR) of bcl-2 provides an extremely sensitive method to detect minimal disease in approximately 50% of patients with non-Hodgkin's lymphomas (NHL). In an attempt to determine the clinical usefulness of this technique, we examined the bone marrow (BM) of 152 patients with advanced-stage NHL at the time of evaluation and after induction or salvage chemotherapy before autologous BM transplantation. The BM proved to be an accessible and reproducible tissue source to determine PCR positivity because all of the 102 patients examined had the same PCR-amplifiable breakpoint in their BM and lymph node. At the time of evaluation, PCR analysis in advanced- stage NHL patients added little additional information to morphologic analysis because each technique identified BM infiltration in approximately 70% of patients. PCR was significantly more useful in determining BM infiltration after induction or salvage therapy. At that time, approximately 50% of patients had morphologically normal BM, whereas PCR analysis remained positive in 100% of those with an amplifiable breakpoint. These observations were confirmed in a clinical trial attempting to induce remission in previously untreated low-grade advanced-stage NHL patients. In this series, PCR was positive in all patients after treatment although the BM was histologically uninvolved in 50% of cases, showing that conventional therapy did not eradicate bcl-2-positive cells.

Clinical and pathologic features of 24 patients with large cell lymphomas that expressed the activation antigen Ki-1 are described. Phenotypic and/or genotypic studies characterized these neoplasms as T-cell (16 cases), B-cell (six cases), or null cell (two cases) type. Males predominantly were affected. Age of patients ranged from 19 to 73 years, with a bimodal distribution, with peaks in the third and seventh decades. Lymphadenopathy was present in nearly all patients. Extranodal involvement, including skin, soft tissue, bone, central nervous system, lung, or small intestine was observed in a total of 54% of the patients, either at presentation or during the course of disease. "Prototypic" features of large cell anaplastic lymphomas were observed for eight T-cell lymphomas, with morphologic heterogeneity noted for the remainder. Eight patients, all with T-cell neoplasms (only one with prototypic morphology), have died of lymphoma (median survival, 5 months). An antecedent history of a lymphoproliferative disorder (mycosis fungoides, B-cell lymphoma, immunoblastic lymphadenopathy) was apparent in seven patients. An 8-year history of Crohn's disease occurred in one patient with a T-cell lymphoma involving small intestine. Phenotypically, loss of one or more markers was typically noted for T-cell neoplasms. Leukocyte common antigen was detected in all cases, although partial loss of immunoreactivity was noticed in some cases. Nearly all cases evaluated for Ia antigen or alpha-1-antichymotrysin were reactive. Eleven of 16 T-cell, two of six B-cell, and two null cell lymphomas expressed epithelial membrane antigen. Ki-1-positive large cell lymphomas are characterized by clinical, morphologic, and immunophenotypic heterogeneity.

Primary cutaneous anaplastic large-cell lymphoma (ALCL) ordinarily is distinguished from systemic ALCL by clinical presentation, absence of anaplastic lymphoma kinase (ALK) expression, and immunophenotype (CLA+, EMA/MUC1-). We present an exceptional case of an elderly man with primary cutaneous ALCL and no systemic disease for a 13-year period. Recurrent skin tumors in this patient were characterized by anaplastic, often multinucleated, cells infiltrating the lymphatics and associated with pseudoepitheliomatous hyperplasia. Cutaneous lymphocyte antigen was absent and EMA/MUC1, typical of systemic ALCL, was strongly expressed by the tumor cells. Remarkably, the tumor cells expressed a cytoplasmic-only variant of ALK protein, as reported in 3 previous cases of primary cutaneous ALCL. Fluorescence in situ hybridization revealed lack of rearrangements of the chromosome 2 ALK gene locus usually involved by translocation t(2;5) or other chromosomal rearrangements that generate nucleophosmin-ALK or the variant ALK fusions that occur in systemic ALCL. Nonetheless, the cytoplasmic ALK protein in the patient's tumor cells was shown to be phosphorylated/activated, suggesting a novel mechanism of ALK activation. Primary cutaneous ALCL of this novel subtype should be distinguished from systemic ALCL to ensure proper clinical management.

To the authors' knowledge, there are no reliable markers able to identify patients with nonsmall cell lung cancer (NSCLC) that will develop metastases to the brain. The authors investigated associations between immunohistochemical markers and the development of brain metastases in patients with NSCLC.This was a hospital-based, case-control study of patients who were newly diagnosed with NSCLC between 1989 and 2003, developed brain metastases, and had pathology material available from both the primary NSCLC and the brain metastases. These patients were compared with a control group of patients who had NSCLC and no evidence of brain metastases. NSCLC was examined for expression levels of Ki-67, caspase-3, vascular endothelial growth factor A (VEGF-A), VEGF-C, E-cadherin, and epidermal growth factor receptor (EGFR) in 54 surgical pathology specimens using immunohistochemistry, and associations were evaluated between those markers and the development of brain metastases.Brain metastases developed after a median of 12.5 months (range, 1.7-89.4 months) after the diagnosis of NSCLC. A significantly increased risk of developing brain metastases was associated with patients with NSCLC who had primary tumors with high Ki-67 levels (adjusted odds ratio [OR] of 12.2; 95% confidence interval [95% CI], 2.4-70.4 [P.001]), low caspase-3 expression (adjusted OR of 43; 95% CI, 5.3 to100 [P.001]), high VEGF-C expression (adjusted OR of 14.6; 95% CI, 2.0 to100 [P.001]), and low E-cadherin (adjusted OR of 3.6; 95% CI, 0.9-16.4 [P = .05]). No significant risk was associated with VEGF-A or EGFR expression. High Ki-67 expression also was associated with a shorter overall survival (P = .04).The results of the current study indicated that patients with NSCLC who had high Ki-67 expression, low caspase-3 expression, high VEGF-C expression, and low E-cadherin expression in their tumors may benefit from close surveillance because they may have an increased risk of developing brain metastases.

To define the role of intensive combination chemotherapy in the treatment of low-grade or intermediate-grade lymphomas, the authors report results in 49 patients treated with intermediate-dose or high-dose methotrexate, bleomycin, Adriamycin (doxorubicin; Adria Laboratories, Columbus, OH), cytoxan (cyclophosphamide), vincristine, and dexamethasone (m/M-BACOD) with long-term follow-up. The complete response rate was 59% (29 of 49), including 67% (eight of 12) with low-grade and 57% (21 of 37) with intermediate-grade disease. The median survival for the entire group was 81 months. The 29 complete responders had a long median survival of 131 months. Forty-five percent (13 of 29) of the complete responders, 27% of the entire group, continue in remission with a median disease-free survival of 76 months. This includes five of 19 patients with diffuse poorly differentiated lymphoma, a disease generally characterized by early relapse. Twelve patients achieved a partial response and had a shorter median survival of 53 months, whereas nonresponders survived a median of less than 5 months. Late relapse was noted in patients with low-grade and intermediate-grade disease. Age (younger than or older than 60 years) was the only predictor of long-term survival. These data indicate very long disease-free survival can be achieved in low-grade and intermediate-grade lymphomas after attaining a complete remission. Intensive doxorubicin containing chemotherapy can be considered as an option for patients with advanced low-grade lymphoma but can only be proven to be superior to single-agent chemotherapy or no initial therapy by controlled randomized trails.

Antibody beta F1 to a common framework determinant of the beta subunit of the T-cell receptor (TCR) was used as a specific phenotypic marker for T-cell differentiation in malignant lymphomas. Sensitivity of immunoperoxidase staining in paraffin sections was enhanced by pronase pretreatment, overnight incubation of primary antibody in Tween 20, and use of streptavidin horseradish peroxidase complexes to amplify the reaction. All 43 cases of B-cell lymphoma were negative for TCR. Reed Sternberg (RS) cells in 3 of 20 cases of Hodgkin's disease exhibited cell membrane staining for TCR (all nodular sclerosis type), further evidence that some RS cells may be T-cell derived. Twenty-nine of 44 cases of T-cell lymphoma expressed TCR (66%). These included 11 of 12 cases of peripheral T-cell lymphoma (PTCL) of small and mixed cell type, 8 of 9 cases of lymphoepithelioid cell (Lennert's) lymphoma, and 2 of 4 cases of T-cell lymphoblastic lymphoma. Loss of immunoreactivity for TCR occurred in lymphomas of large or activated T-cell type, including 7 of 9 cases of T-cell immunoblastic lymphoma and 3 of 4 cases of large cell PTCL. Antibody beta F1 is a specific and relatively sensitive marker of T-cell phenotype in formalin-fixed paraffin sections of malignant lymphomas.

The clinical, pathologic, and immunologic features of 78 cases of peripheral/post-thymic T-cell lymphomas are described. These neoplasms were extremely heterogeneous and were classified as small lymphocytic, mixed small and large cell, large cell, lymphoepithelioid cell, angiocentric, and adult T-cell leukemia/lymphoma type. Some cases revealed angioimmunoblastic or Hodgkin's-like features. These neoplasms mainly affected older adults (mean age, 57 years; median age, 60 years). Lymphadenopathy represented the most frequent clinical presentation, although most patients demonstrated both nodal (87%) and extranodal involvement (77%) during the course of disease. Sites of extranodal disease included skin/soft tissue, spleen, lung, liver, bone, gastrointestinal tract, central nervous system, peripheral blood, nasopharynx, and retrovaginal tissue. Splenomegaly at presentation was most frequently observed in lymphoepithelioid cell lymphomas. Angiocentric lymphomas involved lung. A mediastinal presentation was typically observed in young adults and associated with a poor prognosis. Patients with gastrointestinal lymphomas presented with bleeding and/or malabsorption. B symptoms were present in most cases (65%). Hypercalcemia occurred in four patients. Phenotypic studies of T-cell antigens demonstrated the loss of one or more pan-T-cell markers in eight of 47 cases evaluated. Assessment of T-cell subsets revealed a helper/inducer phenotype for nearly all immunoreactive cases. For the overall series, 32 patients died of disease (median survival time, 11.5 mo). There was a statistical difference between the combined groups of small lymphocytic and lymphoepithelioid cell types as compared with mixed and large cell types, with a poorer survival for the latter group. Angiocentric and adult T-cell leukemia/lymphoma were associated with poor survival. This series of T-cell lymphomas further documents the marked heterogeneity of this group of neoplasms as well as the poor prognosis observed for certain histologic types.

Pulmonary Langerhans cell histiocytosis (LCH) is an idiopathic condition affecting predominantly adult smokers. Histologically, LCH is characterized by a nodular, interstitial proliferation of Langerhans cells around the distal airways with associated eosinophils, lymphocytes, and macrophages. Associated findings, such as fibrosis, emphysematous change, and bronchiolitis can be reminiscent of other interstitial lung diseases. The markers CD1a and S100 have traditionally been used to distinguish LCH from other processes. Little is known about expression of the Langerhans cell-specific lectin, langerin, in pulmonary diseases. We examined the expression patterns of S100, CD1a, and langerin in LCH and other interstitial, inflammatory, and infectious processes in cases retrieved from the files at Brigham and Women's Hospital Department of Pathology. Immunoreactivity was scored according to the number of cells staining per high power field (400x) in areas of highest density, averaged over 4 fields. Cases diagnosed as LCH based on histomorphology and positive CD1a and S100 staining demonstrated strong langerin positivity in lesional tissue. All cases of LCH contained greater than 30 langerin and CD1a positive cells per high power field (HPF), with a mean of100 cells per HPF, in lesional tissue. Of the other interstitial processes examined, only usual interstitial pneumonia demonstrated increased number of Langerhans cells within epithelium and interstitium (mean 14 cells per HPF) as compared with normal lung (mean 6 cells per HPF). Langerin and CD1a serve as specific diagnostic markers in distinguishing LCH from other interstitial and inflammatory processes.

Summary Multiple myeloma (MM) evolves from a highly prevalent premalignant condition termed MGUS. The factors underlying the malignant transformation of MGUS are unknown. We report a MGUS/MM phenotype in transgenic mice with Eμ-directed expression of the XBP-1 spliced isoform (XBP-1s), a factor governing unfolded protein/ER stress response and plasma-cell development. Eμ-XBP-1s elicited elevated serum Ig and skin alterations. With age, Eμ-xbp-1s transgenics develop features diagnostic of human MM, including bone lytic lesions and subendothelial Ig deposition. Furthermore, transcriptional profiles of Eμ-xbp-1s lymphoid and MM cells show aberrant expression of known human MM dysregulated genes. The similarities of this model with the human disease, coupled with documented frequent XBP-1s overexpression in human MM, serve to implicate XBP-1s dysregulation in MM pathogenesis.

Lymphomas represent nearly 70 distinct diseases with unique clinical presentations, therapeutic responses and underlying biology. There is a pressing shortage of publically available cell line and in vivo models of nearly all of these diseases, which has severely hampered efforts to understand and target their biology. To address this issue, we have established a repository of patient-derived xenografts (PDX) of lymphomas by engrafting human tumors into immunodeficient NOD/SCID/IL2rgnull (NSG) mice. These lymphomas, along with a spectrum of other PDXs of hematologic malignancies, are available to collaborators through the online portal PRoXe (Public Repository of Xenografts) at http://PRoXe.org. Blood and bone marrow specimens involved with tumor are injected by tail vein (IV) injection. Lymph node and extranodal biopsy specimens are implanted under the renal capsule as a 1x1x2mm tumor seed (renal), which maintains the in situ microarchitecture. A full description of xenografted lymphomas is included in the Table. Table 1.DiseaseType of implant# in 1st passage# in 2nd passage or higherT-cell prolymphocytic leukemiaIV1Angioimmunoblastic T-cell lymphomaIV11Mantle cell lymphomaIV12Double-hit DLBCLIV2Sézary SyndromeIV1Adult T-cell Leukemia/LymphomaIV1Diffuse large B cell lymphomaIV2Diffuse large B cell lymphomarenal2Marginal zone lymphomarenal11NK/T-cell lymphomarenal1Peripheral T-cell lymphoma-NOSrenal1Breast implant-associated anaplastic large cell lymphomarenal1 Engrafted PDXs have been extensively characterized by immunohistochemistry, flow cytometry, transcriptome sequencing and targeted DNA sequencing. Flow cytometric analysis of patient tumors and their respective xenografts consistently revealed highly concordant immunophenotypes compared to the original tumors. Similarly, immunohistochemistry of involved tissues confirmed retention of tumor immunophenotypes, architecture, and even tissue tropism in the PDXs. Examples include a Sézary syndrome PDX that was injected by tail vein and trafficked to spleen, bone marrow, blood and skin, a diffuse large B-cell lymphoma (DLBCL) PDX that infiltrated the CNS, and a second DLBCL PDX that was implanted into the renal capsule of the left kidney and progressed within 8 weeks to bilateral renal involvement. Other notable models include a breast implant-associated, ALK-negative anaplastic large cell lymphoma implanted under the renal capsule that metastasized to the liver and spleen while uniformly retaining CD30 positivity. Two double-hit lymphoma (DHL) PDXs maintained their CD20-negative phenotype through serial passage to P1. A peripheral T-cell lymphoma-NOS (PTCL) specimen implanted under the renal capsule engrafted in the spleen, with a notable admixture of nonmalignant T cells and scattered EBV-positive B cells. T-cell receptor gene rearrangement PCR performed on this PTCL demonstrated an identical rearrangement pattern in the primary tumor and the PDX. Luciferized mantle cell lymphoma and DHL PDXs clearly home to bone marrow, lymph nodes, spleen, and liver as early as two weeks after injection. These findings support the utility of these PDX lines as in vivo models that more accurately recapitulate the human disease than commonly used subcutaneous cell line models. In addition to generating PDXs that remain faithful to their source tumors, we have witnessed interesting examples of in vivo histologic transformation, opening the door to studies of disease progression. One primary follicular lymphoma specimen injected into a cohort of mice transformed to DLBCL in one mouse and a lymphoblastic lymphoma-like disease in another mouse, as confirmed by IHC and flow cytometry. Further xenografting of primary tumors is underway with the goal of establishing a large repository of lymphoma PDXs useful for biologic interrogation and preclinical trials. Disclosures Davids: Genentech: Other: ad board; Pharmacyclics: Consultancy; Janssen: Consultancy. Shipp:Gilead: Consultancy; Sanofi: Research Funding; BMS: Membership on an entity's Board of Directors or advisory committees, Research Funding; Bayer: Membership on an entity's Board of Directors or advisory committees, Research Funding; Merck: Membership on an entity's Board of Directors or advisory committees.

Diffuse large B-cell lymphoma (DLBCL) is a clinically and biologically heterogeneous disease defined by different transcriptional classifications, associated signaling and survival pathways and additional recurrent genetic alterations. In the cell-of-origin (COO) scheme, DLBCLs subtypes share certain features with normal germinal center B-cells (GCB) and activated B-cells (ABC). In comparison to GCB DLBCLs, ABC tumors have increased baseline NFκB activity and more frequent genetic alterations of NFκB pathway components. DLBCLs with shared functional features are also defined by the consensus clustering classification (CCC) which delineates B-cell receptor (BCR), Oxidative Phosphorylation (OxPhos) and Host Response (HR) tumors. BCR DLBCLs have increased reliance on BCR-signaling and survival pathways and aerobic glycolysis. BCR-dependent DLBCLs with high or low baseline NFκB activity (which largely correspond to ABC or GCB tumors, respectively) have distinct SYK-PI3K-dependent survival pathways and shared sensitivity to proximal BCR pathway inhibitors. Although DLBCLs have infrequent inactivating somatic mutations of TP53, these tumors commonly have copy number alterations (CNAs) of TP53 and genes encoding cell cycle pathway components. Given the clinical and molecular heterogeneity of DLBCL, we sought to develop faithful subtype-specific model systems to assess targeted therapies. Fresh tumor biopsies from 27 primary LBCLs were implanted under the renal capsule of immune compromised NSG mice. Nine of 27 tumors were successfully expanded in vivo, serially propagated for > 5 generations and considered stable LBCL PDX models. All models were EBV- and had clonal IgH rearrangements. Morphological and immunohistochemical signatures defined 8 PDX models as DLBCL and 1 as EBV- plasmablastic lymphoma (PBL). All LBCL PDX models were subjected to RNA-Seq and classified with respect to COO and CCC subtypes. Models were also evaluated by whole exome sequencing with a modified bait set which captured coding mutations and selected chromosomal rearrangements. Six of 9 DLBCL PDX models were ABC type. These models exhibited mutations of MYD88 alone or in association with PIM1 or CD79B with other alterations, as reported in primary ABC DLBCLs. The remaining 2 DLBCL PDX models were GCB type, with characteristic alterations of GNA13 and EZH2, and chromosomal translocations involving IgH and either BCL2 or MYC. Of note, BCL2 and MYC translocations are known adverse prognostic features of primary GCB DLBCL. Certain PDX models had additional mutations including B2M, MLL2, TNFAIP3, MEF2B and TP53. Only 25% (2/8) of the DLBCL PDX models harbored inactivating TP53 mutations whereas 75% (6/8) of tumors exhibited CNAs of TP53 or its upstream modifier, CDKN2A. These data are consistent with the reported incidence and type of TP53 pathway alterations in primary DLBCLs and contrast sharply with the near-uniform presence of TP53 mutations in DLBCL cell lines. Using the CCC classification, 6/8 DLBCL PDX models (both GCBs and 4 of 6 ABCs) were defined as BCR-subtype and 2 models as non-BCR type. To assess the utility of the DLBCL PDX models for functional analysis of BCR signaling, we first assessed cell surface immunoglobulin (sIg) expression by flow cytometry. All 6 BCR-type DLBCLs expressed sIgM whereas the 2 non-BCR DLBCL models and the PBL model lacked sIg. Next, we treated viable tumor cell suspensions with a selective SYK inhibitor, entospletinib (GS-9973). SYK inhibition significantly decreased the proliferation of all 6 BCR-type DLBCLs, but had no effect on the non-BCR-type DLBCLs or the PBL PDX. Given the distinctive SYK/PI3K-dependent signaling and survival pathways in DLBCLs with low or high baseline NFκB, we also assessed selective apoptotic pathway readouts in entospletinib-treated PDX cell suspensions. SYK inhibition selectively upregulated the pro-apoptotic BH3 family member, HRK, in BCR-dependent GCB-type DLBCL PDX samples and significantly downregulated the anti-apoptotic BCL2 family member, BCL2A1, in BCR- dependent ABC-type DLBCL PDX tumors, effects consistent with those previously observed in primary DLBCL samples. In summary, we have established and molecularly characterized faithful PDX models of DLBCL and PBL and demonstrated their usefulness in evaluating novel BCR pathway inhibitors. Disclosures Rodig: Perkin Elmer: Membership on an entity's Board of Directors or advisory committees; BMS: Research Funding. Shipp:Gilead: Consultancy; Sanofi: Research Funding; Merck: Membership on an entity's Board of Directors or advisory committees; Bayer: Membership on an entity's Board of Directors or advisory committees, Research Funding; BMS: Membership on an entity's Board of Directors or advisory committees, Research Funding.

Outcomes among persons with lymphoma in sub-Saharan African (SSA) remain poor, largely due to resource limitations in diagnostics, therapeutics and supportive care. We hypothesized that subclassification of lymphoma specimens from SSA could improve diagnostic accuracy, thereby altering treatment recommendations and identifying cases responsive to less toxic, targeted agents. The Queen Elizabeth Central Hospital (QECH) in Malawi serves as the teaching hospital for the University of Malawi College of Medicine (UOMCOM) in Blantyre, Malawi's largest city. Pathologic diagnosis of lymphoma at QECH/UOMCOM is based solely on HE 25% £ 16); 274 males, 189 females, 35 unknown. HIV status was available for 10% (36 reactive; 12 non-reactive). At Brigham and Women's Hospital, we performed immunohistochemistry (IHC) for 28 markers and classified each case per the 2008 WHO Classification. 170 cases (34%) could not be classified, largely due to poor tissue antigenicity or lack of lesional tissue on TMA. The remaining 328 cases (66%) are classified in the Table . 37% of the 133 DLBCL were germinal center B cell-like (GCB), 59% non-GCB, and 4% could not be characterized (Hans criteria). We also performed targeted expression profiling with a previously-published, NanoString-based diagnostic molecular classifier of aggressive B-cell lymphomas. This classifier distinguishes ~85% of pathological BL cases from DLBCL in Western cohorts (Carey CD, J Mol Diagn 2015). Evaluable RNA was available in 64/133 (48%) DLCBL, 38/73 (52%) BL, and 8/9 (89%) BCL-U cases. Unsupervised clustering of transcriptional profiles identified 2 groups (n = 54, 56). All 38 BL cases were classified into Group I (100%; exact binomial 95% CI: 91-100), along with 14 DLBCL (22%; 13-34%) and 4 BCL-U (50%; 16-84%). Group II combined 50 of 64 DLBCL cases (78%; 66-87%), 4 of 8 BCL-U cases (50%; 16-84%), and no BL (0%; 0-9%). Concordance between the classifier and pathologic diagnosis was 84%. Overall, incorporation of phenotypic and transcriptional data allowed reclassification of 83 cases into categories that may be responsive to ibrutinib or idelalisib (MCL; non-GCB DLBCL; CLL/SLL); 75 into categories that could benefit from CHOP (ALCL; DLBCL; PBL; PTCL-NOS); 8 into T-ALL; and 30 additional cases of BL by IHC alone. 18 cases of DLBCL or BCL-U were also found to have a similar transcriptional profile to BL, suggesting that they may benefit from BL-directed therapy. Thus, our findings demonstrate that ancillary phenotypic and transcriptional characterization can reclassify a large fraction of lymphomas in SSA and guide potentially beneficial therapies. Implementation of these tools and enhanced drug access and supportive care are desperately needed to improve patient outcomes across the developing world. | | | Original Pathologic Classification (Malawi) | | --------------------------------- | --------------- | ------------------------------------------- | ---------------------------------------------------- | | | | DLBCL/high grade NHL (n=118) | NHL/low grade NHL/lymphoma NOS/low grade BCL (n=101) | BL (n=70) | Suspicious for NHL (n=21) | CLL/SLL (n=7) | FL (n=3) | ALCL (n=2) | LBL (n=1) | MZL (n=3) | PBL (n=2) | | Refined Diagnosis Using IHC n (%) | DLBCL | 70 (59) | 46 (45) | 8 (12) | 7 (32) | | 1 (33) | 1 (50) | | | | | | BL | 12 (10) | 14 (14) | 43 (62) | 4 (19) | | | | | | | | | PBL | 11 (9) | 2 (2) | 5 (7) | 1 (5) | | | | 1 (100) | | | | | BCL-U | 4 (3) | | 3 (4) | | 1 (14) | | | | | 1 (50) | | | CD5-/CD10- BCL | 10 (9) | 13 (13) | 2 (3) | | 2 (29) | 2 (67) | | | | | | | CLL/SLL | | 2 (2) | | | 4 (57) | | | | | | | | MCL | | 2 (2) | | | | | | | | | | | FL | | 1 (1) | | | | | | | | | | | MZL | | | | 2 (10) | | | | | 2 (67) | | | | ALK+ ALCL | | 1 (1) | | 1 (5) | | | | | | | | | PTCL, NOS | | | 1 (1) | | | | | | | | | | T-ALL | 2 (2) | 3 (3) | 1 (1) | 2 (10) | | | | | | | | | Myeloid sarcoma | | 2 (2) | | | | | | | 1 (33) | | | | cHL | 1 (1) | 1 (1) | 1 (1) | | | | 1 (50) | | | | | | Plasmacytoma | | 1 (1) | | | | | | | | 1 (50) | | | Reactive | | 1 (1) | | | | | | | | | | | Carcinoma NOS | 2 (2) | 6 (6) | | | | | | | | | | | Neuroendocrine | 6 (5) | 6 (6) | 6 (9) | 4 (19) | | | | | | | * CLL/SLL,chronic lymphocytic leukemia/small lymphocytic lymphoma;FL,follicular lymphoma;ALCL,anaplastic large cell lymphoma;LBL,lymphoblastic lymphoma;MZL,marginal zone lymphoma;PBL,plasmablastic lymphoma;BCL-U,BCL,unclassifiable,with features intermediate between DLBCL & BL;MCL,mantle cell lymphoma;PTCL-NOS,peirpheral T-cell lymphoma,not otherwise specified;T-ALL,T-lymphoblastic lymphoma;cHL,classical Hodgkin lymphoma Table 1. Disclosures Rodig: Bristol Myers Squibb: Research Funding; Perkin Elmer: Membership on an entity's Board of Directors or advisory committees.

Dendritic cells (DCs), immune system cells central to the development of immunity, have not previously been reported in muscle in inclusion-body myositis (IBM). We performed immunohistochemical studies on muscle biopsy specimens from 50 patients using monoclonal antibodies that distinguish two classes of DCs, myeloid DC and plasmacytoid DC. In 17 of 20 IBM and 9 of 10 polymyositis (PM) specimens, myeloid DCs were present in substantial numbers, frequently surrounded and sometimes invading otherwise intact myofibers, and were part of dense collections of cells that included T cells. Dermatomyositis muscle had more plasmacytoid DCs than myeloid DCs, whereas IBM and PM had greater numbers of myeloid DCs. The stellate morphology of myeloid DCs in dense collections of cells that included T cells suggests local intramuscular antigen presentation in IBM and PM.

Intravascular lymphoma (IVL) is a rare subtype of extranodal diffuse large B-cell lymphoma in the World Health Organization classification. Although the majority of cases are of B-cell lineage, cases of IVL with a T-cell phenotype and, rarely, histiocytic and natural killer (NK)-cell phenotypes have been reported. We report a case of T-cell IVL with a cytotoxic phenotype. A 62-year-old male presented with erythematous patches and plaques on the lower extremities, and a biopsy revealed IVL with an activated cytotoxic phenotype (CD56(+), perforin+, granzyme B+, TIA-1+, CD3epsilon(+), CD20(-), CD4(-), CD8(-), CD5(-), and T-cell receptor [TCR] betaF1(-)), consistent with either NK-cell or T-cell origin. TCR gene analysis showed a monoclonal T-cell population, supporting the diagnosis of a T-cell IVL. Although the patient's skin lesions were refractory to combination chemotherapy and salvage chemotherapy regimens, there has been no evidence of disease progression in 24 months of follow-up.

Primary mediastinal large B-cell lymphoma (MLBCL) shares important clinical and molecular features with classic Hodgkin lymphoma, including nuclear localization of the nuclear factor kappaB (NFkappaB) subunit c-REL (reticuloendotheliosis viral oncogene homolog) in a pilot series. Herein, we analyzed c-REL subcellular localization in additional primary MLBCLs and characterized NFkappaB activity and function in a MLBCL cell line. The new primary MLBCLs had prominent c-REL nuclear staining, and the MLBCL cell line exhibited high levels of NFkappaB binding activity. MLBCL cells expressing a superrepressor form of inhibitor of kappa B alpha signaling (IkappaB alpha) had a markedly higher rate of apoptosis, implicating constitutive NFkappaB activity in MLBCL cell survival. The transcriptional profiles of newly diagnosed primary MLBCLs and diffuse large B-cell lymphomas (DLBCLs) were then used to characterize the NFkappaB target gene signatures of MLBCL and specific DLBCL subtypes. MLBCLs expressed increased levels of NFkappaB targets that promote cell survival and favor antiapoptotic tumor necrosis factor alpha (TNFalpha) signaling. In contrast, activated B cell (ABC)-like DLBCLs had a more restricted, potentially developmentally regulated, NFkappaB target gene signature. Of interest, the newly characterized host response DLBCL subtype had a robust NFkappaB target gene signature that partially overlapped that of primary MLBCL. In this large series of primary MLBCLs and DLBCLs, NFkappaB activation was not associated with amplification of the cREL locus, suggesting alternative pathogenetic mechanisms.

Dermatomyositis has been modeled as an autoimmune disease largely mediated by the adaptive immune system, including a local humorally mediated response with B and T helper cell muscle infiltration, antibody and complement-mediated injury of capillaries, and perifascicular atrophy of muscle fibers caused by ischemia. To further understand the pathophysiology of dermatomyositis, we used microarrays, computational methods, immunohistochemistry and electron microscopy to study muscle specimens from 67 patients, 54 with inflammatory myopathies, 14 with dermatomyositis. In dermatomyositis, genes induced by interferon-alpha/beta were highly overexpressed, and immunohistochemistry for the interferon-alpha/beta inducible protein MxA showed dense staining of perifascicular, and, sometimes all myofibers in 8/14 patients and on capillaries in 13/14 patients. Of 36 patients with other inflammatory myopathies, 1 patient had faint MxA staining of myofibers and 3 of capillaries. Plasmacytoid dendritic cells, potent CD4+ cellular sources of interferon-alpha, are present in substantial numbers in dermatomyositis and may account for most of the cells previously identified as T helper cells. In addition to an adaptive immune response, an innate immune response characterized by plasmacytoid dendritic cell infiltration and interferon-alpha/beta inducible gene and protein expression may be an important part of the pathogenesis of dermatomyositis, as it appears to be in systemic lupus erythematosus.