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Introduction: In 1991, we reported 18 persons with a clinical-pathologic entity and termed atypical myeloproliferative disorder because they did not meet the contemporary diagnostic criteria for a myeloproliferative neoplasm. We sought to gain further knowledge on this disease entity. Methods: This retrospective cohort study included consecutive subjects registered in the database of the Center for the Study of Myelofibrosis in Pavia, Italy, from 1998 to 2020 (June), and diagnosed with atypical myeloproliferative disorder according to our adjudicated criteria. We studied clinical, histological, cytogenetic, and molecular covariates and risks of thrombosis, disease progression, and death. Data were compared with those of concurrent subjects with prefibrotic myelofibrosis. Results: Fifteen new subjects with atypical myeloproliferative disorder were identified. Seven were male. Median age was 50 years (IQR, 41–54 years). Thirteen were diagnosed with a synchronous symptomatic or incidentally detected thrombotic event. The bone marrow showed megakaryocyte hyperplasia with dysplasia. JAK2V617F was present in 10 subjects and CALR mutation in one. No other somatic mutations were identified in next generation sequencing. After a median follow-up of 101 months (IQR, 40–160 months), no subject had disease progression or blast transformation. Incidence of post-diagnosis or recurrent thrombosis was 3.9 events (95% confidence interval, 3.5–4.0) and 5.0 events (4.6–5.6) per 100 person-years. Features of subjects with atypical myeloproliferative disorder differed markedly from those of 546 subjects with prefibrotic myelofibrosis. Conclusion: Our data indicate that these 15 persons have a distinct myeloproliferative neoplasm. We propose naming this new disorder clonal megakaryocyte dysplasia with normal blood values.

The expression of the CXCR4 chemokine receptor on CD34-positive blood cells is reduced in persons with primary myelofibrosis (PMF). We analyzed the relevance of cytofluorimetric assessment of the percentage of CD34-positive blood cells that had a positive CXCR4 surface expression (CD34/CXCR4-se) in a large cohort of subjects with myeloproliferative neoplasms. Mean CD34/CXCR4-se was lower in subjects with PMF compared with those with essential thrombocythemia (ET) or polycythemia vera (PV). A cutoff value of 39% was associated with a diagnosis of pre-fibrotic PMF vs. ET with a positive predictive value of 97%. In PMF male sex, older age, and MPL mutation were independent correlates of reduced CD34/CXCR4-se and associated with a briefer interval to development of severe anemia, large splenomegaly, thrombocytopenia, leukopenia, elevated CD34-positive blood cells, blast transformation and death. We constructed a prognostic model including age >65 years, hemoglobin 50 × 106/L, and CD34/CXCR4-se

We measured plasma levels of high-sensitivity C-reactive protein (hs-CRP) in 526 subjects with primary myelofibrosis (PMF). Thirty-eight percent had an elevated hs-CRP level (≥0.3mg/dL). Elevated hs-CRP levels were associated with a progressive disease phenotype, including anemia, high white blood cell count, low platelet count, increased splenomegaly, increased risk of blast transformation, and worse survival. Age≥52years, but no other demographic characteristics, was associated with an elevated hs-CRP level in multivariable logistic regression (odds ratio [OR], 4.29; 95% CI, 2.73-6.77; P

Myeloproliferative neoplasm (MPN)-associated myelofibrosis is a clonal, neoplastic disorder of the hematopoietic stem cells, in which inflammation and immune dysregulation play an important role. Extracellular nicotinamide phosphoribosyltransferase (eNAMPT), also known as visfatin, is a cytokine implicated in a number of inflammatory and neoplastic diseases. Here plasma levels of eNAMPT in patients with MPN-associated myelofibrosis and their effects on disease phenotype and outcomes were examined. The concordance of eNAMPT levels with the marker of general inflammation high-sensitivity C-reactive protein (hs-CRP) was also studied. A total of 333 MPN-associated myelofibrosis patients (187 males and 146 females) and 31 age- and gender-matched normal-weight healthy subjects were enrolled in the study main body. Levels of eNAMPT and hs-CRP were simultaneously assayed in 209 MPN-associated myelofibrosis patients. Twenty-four polycythemia vera or essential thrombocythemia patients were used as controls. eNAMPT was over expressed in MPN-associated myelofibrosis, and eNAMPT expression was correlated with higher white blood cell count, higher hemoglobin, and higher platelet count, suggesting that eNAMPT is an indispensable permissive agent for myeloproliferation of MPN-associated myelofibrosis. The lack of correlation between eNAMPT and hs-CRP revealed that eNAMPT in MPN-associated myelofibrosis does not behave as a canonical inflammatory cytokine. In addition, higher levels of eNAMPT predicted longer time to blast transformation, and protected against progression toward thrombocytopenia and large splenomegaly. In conclusion, in MPN-associated myelofibrosis high levels of eNAMPT mark the myeloproliferative potential and, at variance with a high number of cancers, are protective against disease progression. Am. J. Hematol. 91:709-713, 2016. © 2016 Wiley Periodicals, Inc.

Background Hepatitis C virus (HCV) infection has been linked to lymphoproliferative disorders. Marginal zone B-cell lymphoma (MZL) represents one of the most frequent lymphoma subtypes associated with HCV infection. We describe an unusual subset of HCV-associated MZL characterized by subcutaneous presentation. Materials and methods A series of 12 HCV-positive patients presenting with subcutaneous nodules that revealed lymphoma infiltration at biopsy. Molecular analysis of immunoglobulin heavy chain (IGH) gene rearrangement and FISH investigations for t(11;18)(q21;q21) and t(14;18)(q32;q21) were carried out in nine patients. Results The 12 patients (median age 69.5 years), all with positive HCV serology, presented with single or multiple subcutaneous nodules resembling lipomas. Histologically the lesions showed lymphoid infiltrates, consistent with extranodal MZL of mucosa-associated lymphoid tissue (MALT). Functional IGH gene rearrangements were identified in nine tested patients, with somatic mutations in 82%, indicating a histogenesis from germinal center-experienced B cells. The t(11;18) was found in two of nine cases. Staging did not show any other lymphoma localization. In two patients, a response was achieved with antiviral treatment. Extracutaneous spread to MALT sites occurred in a case. Conclusions Our observations expand the spectrum of HCV-associated lymphomas to include a subset of extranodal MZL characterized by a novel primary ‘lipoma-like’ subcutaneous presentation and indolent clinical course.

Reported herein is an unusual vascular tumor primary arising in the liver and exhibiting unique histopathological features. A 47-year-old woman underwent left hepatectomy because of a large hepatic mass. On histology the tumor had a composite pattern, consisting of angiomatous, retiform and solid areas, formed by oval to cuboidal to spindle cells, that expressed only endothelial markers (CD31 and factor VIII-related antigen). These findings led to the diagnosis of a low-grade vascular neoplasm with morphological features consistent with so-called polymorphous hemangioendothelioma. The tumor was completely resected. At 24 month follow up the patient was alive, without evidence of disease. Polymorphous hemangioendothelioma is a rare vascular neoplasm, with borderline malignant potential, which usually occurs in lymph nodes and, rarely, at extranodal sites. Its classification as an entity has been questioned recently. The unusual morphological features of the present case, which do not fit neatly with any other recognized hemangioendothelioma subtype, indicate that the family of vascular tumors is broader than currently accepted. In addition the present case widens the spectrum of primary vascular tumors arising in the liver.

In a series of 172 patients with non-Hodgkin's lymphoma (NHL) classified according to the Working Formulation (WF) the overall incidence of bone marrow infiltration (BM +) at diagnosis was 39%: 59% for low-grade (LGML), 30% for intermediate-grade (IGML), and 25% for high-grade malignant lymphomas (HGML). The features most significantly correlated with the presence of BM + were a low grade of histological malignancy, the degree of splenomegaly and high values of LDH, while those correlated with the extent of BM+ were a non-focal pattern of BM disease, the presence of blood involvement at diagnosis, and the degree of BM fibrosis. Blood involvement was detected at diagnosis in 13% of patients, and a further 16% developed a leukemic phase during the course of the disease. Blood involvement correlated significantly with splenomegaly, bulky disease, advanced clinical stage, and extent of BM +. The presence of BM infiltration ‘per se’ at diagnosis did not significantly affect prognosis. However, the extent of BM disease was correlated with a poorer outcome in IGML and HGML patients. Regarding peripheral blood involvement, in LGML patients only late leukemic conversions were significantly associated with a worse prognosis. In patients with IGML and HGML, either initial or subsequent blood involvement was correlated with significantly poorer outcome.

Purpose We studied bone marrow (BM) histologic abnormalities in myelodysplastic syndromes (MDS) classified according to WHO criteria to determine their clinical correlates and prognostic value. Patients and Methods Three hundred one consecutive patients were retrospectively evaluated for BM fibrosis and CD34 immunoreactivity. Marrow fibrosis was assessed following the European consensus guidelines. Results Moderate to severe BM fibrosis was detected in 17% of cases and was associated with multilineage dysplasia (P = .001), high transfusion requirement (P < .001), and poor-risk cytogenetics (P = .007). CD34+ cell clusters were found in 23% of patients and were associated with WHO categories with excess of blasts (P < .001) and poor-risk cytogenetics (P = .001). In multivariable analysis, BM fibrosis and presence of CD34+ cell clusters had independent negative impact on overall survival (P < .001 and P = .019, respectively) and leukemia-free survival (P < .001 and P = .004, respectively). A hierarchical clustering analysis identified three subsets of patients with distinct clinical features. One cluster consisted mainly of patients with BM fibrosis, multilineage dysplasia, and high transfusion requirement; these individuals had lower overall survival and leukemia-free survival (P = .001 and P < .001, respectively). Within patients stratified according to International Prognostic Scoring System and WHO classification–based Prognostic Scoring System categories, BM fibrosis involved a shift to a one-step more advanced risk group. Conclusion BM fibrosis identifies a distinct subgroup of MDS with multilineage dysplasia, high transfusion requirement, and poor prognosis and represents an independent prognostic factor that may be useful in clinical decision making. Furthermore, the presence of CD34+ cell clusters is an independent risk factor for progression to acute leukemia.

We report a case of a patient with myelofibrosis with myeloid metaplasia (MMM) who presented with progressive dyspnea of unexplained origin. Splenomegaly, blood smear, and bone marrow findings allowed diagnosis of MMM. High-resolution CT chest scan revealed diffuse septal thickening, while echocardiography and electrocardiogram showed no indirect evidence of pulmonary hypertension. Finally, lung biopsy revealed irregularly distributed interstitial fibrosis with islands of erythroblasts, immature granulocytic elements, and dysplastic megakaryocytes, allowing diagnosis of pulmonary extramedullary hematopoiesis (EMH). The patient received hydroxyurea as cytoreductive agent, obtaining a good hematologic response and an improvement of dyspnea. Note that, in this patient, dyspnea was the first clinical symptom of MMM; the dyspnea was not associated with pulmonary hypertension and improved following cytoreductive treatment. This case points to the importance of suspecting pulmonary EMH when unexplained progressive dyspnea occurs in a patient with MMM. Early recognition of pulmonary EMH may prevent PH and favor a better response to therapy.

Novel N-glycosylation sites are introduced by somatic mutation into the V genes of the majority of follicular lymphomas. Sites are positively selected and rare in normal memory B cells, indicating a potential role in tumour survival in the germinal centre (GC). The incidence of c. 40% in diffuse large B-cell lymphomas (DLBCL) parallels the known heterogenity of the disease. Immunodeficiency-related non-Hodgkin's lymphomas (NHL) include post-transplant lymphoproliferative disorders (PTLD) and acquired immunodeficiency syndrome-related NHL (AIDS-NHL). Most PTLD derive from B cells that carry mutated VH genes and that have completed the GC reaction. All AIDS-NHL carry mutated VH genes and variable features of GC or post-GC cells. To determine if N-glycosylation is a feature of immunodeficiency-related lymphomas, we analysed the VH genes of 19 PTLD and 36 AIDS-NHL. Novel sites were rare in PTLD (4/19), similar to memory B cells (P = 0·15). AIDS-NHL, including DLBCL and Burkitt's lymphomas (BL), showed heterogeneity with 16 of 36 (44%) having novel sites. The findings indicate no selection of N-glycosylation sites in PTLD, consistent with post-GC features. The variable incidence of N-glycosylation sites in AIDS-NHL mirrors that in DLBCL and sporadic BL of immunocompetent hosts, supporting the known heterogeneity of these disorders, and possibly pointing to distinct routes of tumour development.

Aims: To detail on sequential biopsies the morphological and immunohistochemical features of a case of primary lymph nodal fibroblastic reticulum cell (FBRC) tumour which progressed into a clinically aggressive cytokeratin-positive interstitial reticulum cell (CIRC) sarcoma. Methods and results: A 70-year-old female underwent surgical excision of an enlarged submandibular lymph node. The nodal architecture was effaced by a neoplastic proliferation of medium to large cells, round to oval to spindle in shape, growing in a storiform pattern. The tumour stained for vimentin, CD68, factor XIIIa, α1-antitrypsin, fascin and actin. Dendritic and endothelial cell markers were negative. A diagnosis of FBRC tumour was made by combining pathological and clinical data. The patient received no therapy but 5 months later the tumour relapsed, exhibiting a deceptively pleomorphic cytology, phenotypic changes (strong cytokeratin positivity), intense p53 expression and aggressive clinical course with fatal outcome. In-situ hybridization for Epstein–Barr virus was negative. Conclusions: We speculate that the morphological changes and p53 expression of the relapsing neoplasm might reflect tumour cell dedifferentiation, in keeping with the aggressive clinical course. The intense p53 expression suggests that this oncoprotein might also play a role in reticulum cell tumorigenesis.

May-Hegglin anomaly, Sebastian syndrome, Fechtner syndrome, and Epstein syndrome are autosomal dominant macrothrombocytopenias distinguished by different combinations of clinical and laboratory signs, such as sensorineural hearing loss, cataract, nephritis, and polymorphonuclear Döhle-like bodies. Mutations in the MYH9 gene encoding for the nonmuscle myosin heavy chain IIA (NMMHC-IIA) have been identified in all these syndromes. To understand the role of the MYH9 mutations, we report the molecular defects in 12 new cases, which together with our previous works represent a cohort of 19 families. Since no genotype-phenotype correlation was established, we performed an accurate clinical and biochemical re-evaluation of patients. In addition to macrothrombocytopenia, an abnormal distribution of NMMHC-IIA within leukocytes was observed in all individuals, including those without Döhle-like bodies. Selective, high-tone hearing deficiency and cataract was diagnosed in 83% and 23%, respectively, of patients initially referred as having May-Hegglin anomaly or Sebastian syndrome. Kidney abnormalities, such as hematuria and proteinuria, affected not only patients referred as Fechtner syndrome and Epstein syndrome but also those referred as May-Hegglin anomaly and Sebastian syndrome. These findings allowed us to conclude that May-Hegglin anomaly, Sebastian syndrome, Fechtner syndrome, and Epstein syndrome are not distinct entities but rather a single disorder with a continuous clinical spectrum varying from mild macrothrombocytopenia with leukocyte inclusions to a severe form complicated by hearing loss, cataracts, and renal failure. For this new nosologic entity, we propose the term "MHY9-related disease," which better interprets the recent knowledge in this field and identifies all patients at risk of developing renal, hearing, or visual defects.

PURPOSE To define clinicopathologic features, response to treatment, and prognostic factors of primary mediastinal B-cell lymphoma (MBL), a CD20+ tumor recognized as a distinct entity among non-Hodgkin's lymphomas (NHL). PATIENTS AND METHODS One hundred six patients presented with disease confined to thorax (86%), bulky mediastinum (73%), superior vena cava syndrome (47%), and contiguous infiltration (57%). Ninety-nine received doxorubicin-containing chemotherapy (CHT). RESULTS Thirty-five of 99 patients were primarily CHT-resistant, and 64 responded: 23 achieved complete response (CR) and 41 achieved response with residual mediastinal abnormality. Seventy-seven percent of responders received mediastinal radiotherapy (RT). Of 64 responders, 18 (28%) relapsed: none of 23 CR patients and 18 of 41 (44%) with residual mediastinal abnormality. Relapse-free survival rate of responders was 71% at 3 years. Actuarial 3-year survival rate was 52% for all patients and 82% for responders. Predictive factors of poor outcome were identified by logistic regression; Cox survival analysis was performed on death and relapse. Pericardial effusion (P < .001) and Eastern Cooperative Oncology Group (ECOG) performance status > or = 2 (P = .009) predicted nonresponse (NR) and affected survival. Less than partial midway response to CHT predicted NR to subsequent therapies. Bulky disease was related to persistent mediastinal abnormality and risk of relapse (P = .025). CONCLUSION MBL is an aggressive NHL with unique clinicopathologic aspects, often refractory to current CHT designed for high-grade NHL. Poor performance status and pericardial effusion predict NR and poor survival. Inadequate response after the first courses of front-line CHT predicts failure of subsequent treatment. Responders with bulky mediastinum or residual mediastinal abnormality after CHT are at risk of relapse. These factors should help to select high-risk patients for intensive treatments.

We evaluated the presenting clinical characteristics and outcome of 68 patients with nodular lymphocyte predominance Hodgkin's disease (NLP-HD), in order to delineate the pattern of evolution of the disease. The male to female ratio was 46/22 and median age 35 yrs (range, 14-86). Eight patients had a history of benign hyperplasia on lymph node biopsies performed 6 to 36 months before the diagnosis of NLP-HD. Early stage disease accounted for 75% of cases. One patient had a coexistent non-Hodgkin's lymphoma (NHL). Treatment was as follows: radiotherapy in 26, chemotherapy in 23, combined modality in 19. CR rate was 93% (63/68). 18 patients relapsed as HD and 5 developed NHL. The cumulative risk of NHL was 9% at 10 yrs. During remission, 4 patients had 5 episodes of follicular hyperplasia histologically documented. Overall survival rate was 71% at 10 yrs and and 63% at 15 yrs. Freedom from progression (FFP) declined from 67% at 5 yrs to 45% at 10 yrs, because of late relapses. Localized disease predicted for a better FFP (p = 0.01), but was not associated with a reduced risk of recurrence over time. NLP-HD is characterized by an indolent course with a constant pattern of relapse over time, also in patients with early stage disease at diagnosis. In addition to relapse as NLP-HD, patients may evolve into a NHL or develop benign lymph nodal hyperplasia. Careful long-term follow up is needed for these patients.

Increased microvessel density contributes to abnormal BM and spleen microenvironment in myelofibrosis (MF). Taking advantage of the JAK2V617F mutation as a marker of malignancy, in the present study, we investigated whether splenic endothelial cells (ECs) obtained from capillaries by laser microdissection or from fresh spleen tissue by cell culture or cell sorting harbored such mutation in patients bearing the mutation in their granulocytes and undergoing splenectomy for therapeutical reasons. To extend the analysis to the ECs of large vessels, endothelial tissue from the splenic vein was also studied. We found JAK2V617F+ ECs in 12 of 18 patients also bearing the mutation in their granulocytes. In 3 patients, the mutation was found in at least 2 different EC samples obtained by laser microdissection, cell culture, or cell sorting. The mutation was detected in the splenic vein ECs of 1 of 6 patients investigated. In conclusion, we provide evidence that some ECs from the spleen and splenic veins of patients with MF bear the JAK2V617F mutation. We suggest that splenic ECs are involved in the process of malignant transformation in MF.

Splenic marginal zone (MRZ) cell lymphoma is a recently described neoplasm arising in a unique compartment of splenic white pulp, producing massive splenomegaly and spreading to bone marrow and distant lymph nodes. We report three cases of splenic lymphoma that morphologically and immunohistochemically appear to originate from MRZ cells that presented as indolent neoplasms involving the spleen but with no or only moderate enlargement of the organ, presumably representing an early clinical stage of this disorder. Despite the evidence of involvement of the liver in one case, lymph nodes and bone marrow proved to be uninvolved. Histologically, the three spleens showed similar features, being characterized by the involvement of white pulp follicles and periarteriolar lymphoid sheaths by medium-sized lymphoid cells with slightly irregular nuclei and ample cytoplasm. Immunohistochemically, all the specimens expressed a series of B-lineage markers that, in contrast to specimens of monocytoid B cell lymphoma (MBCL) and hairy cell leukemia (HCL) studied for comparison, did not react with KiB3, LN1, and DBA.44 monoclonal antibodies.

PurposeIn the WHO diagnostic classification, prefibrotic myelofibrosis (pre-MF) is included in the category of primary myelofibrosis (PMF). However, strong evidence for this position is lacking.Patients and methodsWe investigated whether pre-MF may be aligned along a clinical and biological continuum in 683 consecutive patients who received a WHO diagnosis of PMF.ResultsAs compared with PMF-fibrotic type, pre-MF (132 cases) showed female dominance, younger age, higher hemoglobin, higher platelet count, lower white blood cell count, smaller spleen index and higher incidence of splanchnic vein thrombosis. Female to male ratio and hemoglobin steadily decreased, while age increased from pre-MF to PMF- fibrotic type with early and to advanced bone marrow (BM) fibrosis. Likely, circulating CD34+ cells, LDH levels, and frequency of chromosomal abnormalities increased, while CXCR4 expression on CD34+ cells and serum cholesterol decreased along the continuum of BM fibrosis. Median survival of the entire cohort of PMF cases was 21 years. Ninety-eight, eighty-one and fifty-six percent of patients with pre-MF, PMF-fibrotic type with early and with advanced BM fibrosis, respectively, were alive at 10 years from diagnosis.ConclusionPre-MF is a presentation mode of PMF with a very indolent phenotype. The major consequences of this contention is a new clinical vision of PMF, and the need to improve prognosis prediction of the disease.

Nosological classification of sinus histiocytosis with massive lymphadenopathy (SHML; Rosai-Dorfman disease) is difficult, and the normal cellular counterpart of Rosai-Dorfman (RD) cells is uncharacterised. The peculiar S-100+ phenotype of RD cells suggests a relationship with the dendritic cell family. Recent investigations have revealed cathepsin E to be selectively concentrated in antigen-presenting cells, whereas cathepsin D was found to be expressed in cells of macrophage lineage. Cathepsin D and E distribution was investigated by immunohistochemistry in a series of SHML biopsies and in two types of dendritic cell proliferative lesions: dermatopathic lymphadenitis (DL) and Langerhans' cell histiocytosis (LCH). In SHML biopsies, RD cells and monocyte-related elements of the sinuses and pulp coexpressed cathepsin D and E. LCH cells also stained for both these aspartic proteinases. Conversely, in DL cathepsin E and D were localised to separate cells that resembled Langerhans' cells (LC) or macrophages, respectively, in morphology and distribution. Our data outline the peculiar immunophenotype of RD and LCH cells and suggest that caution should be exercised in the identification of their normal cellular counterpart. The common expression of cathepsin D and E and of S-100 protein suggests some phenotypic overlap between SHML and LCH cells, despite their striking morphological divergence.

An adult patient had a syndrome associating the features of juvenile dermatomyositis and cutaneous polyarteritis nodosa that followed a cyclic course from childhood; recurrences were always associated with a rise of serum antistreptococcal antibodies. Regions of homology between streptococcal type 5 M protein and skeletal myosin were found. These findings suggest that streptococcal infection, possibly through a molecular mimicry mechanism, played a role in the pathogenesis of the disease in our patient.

Composite lymphomas have rarely been reported in Hodgkin's disease (HD), except in the lymphocyte predominance sub-type, and immunohistochemical investigations have been performed in only few cases. We describe the histological and immunophenotypical findings in a case of composite nodular sclerosing HD and high-grade, large cell non-Hodgkin's lymphoma (NHL). In our case HD and NHL cells displayed striking morphological and immunophenotypical divergence, suggesting a lack of correlation between the two neoplasms.

The autosomal dominant, giant-platelet disorders1, May-Hegglin anomaly2, 3 (MHA; MIM 155100), Fechtner syndrome4 (FTNS; MIM 153640) and Sebastian syndrome5 (SBS), share the triad of thrombocytopenia, large platelets and characteristic leukocyte inclusions (?Döhle-like? bodies). MHA and SBS can be differentiated by subtle ultrastructural leukocyte inclusion features, whereas FTNS is distinguished by the additional Alport-like clinical features of sensorineural deafness, cataracts and nephritis4. The similarities between these platelet disorders and our recent refinement of the MHA (ref. 6) and FTNS (ref. 7) disease loci to an overlapping region of 480 kb on chromosome 22 suggested that all three disorders are allelic. Among the identified candidate genes is the gene encoding nonmuscle myosin heavy chain 9 (MYH9; refs 8?10), which is expressed in platelets9 and upregulated during granulocyte differentiation10. We identified six MYH9 mutations (one nonsense and five missense) in seven unrelated probands from MHA, SBS and FTNS families. On the basis of molecular modelling, the two mutations affecting the myosin head were predicted to impose electrostatic and conformational changes, whereas the truncating mutation deleted the unique carboxy-terminal tailpiece. The remaining missense mutations, all affecting highly conserved coiled-coil domain positions, imparted destabilizing electrostatic and polar changes. Thus, our results suggest that mutations in MYH9 result in three megakaryocyte/platelet/leukocyte syndromes and are important in the pathogenesis of sensorineural deafness, cataracts and nephritis.

Background: Among marginal zone lymphomas (MZLs), bone marrow (BM) involvement features are well established in the splenic marginal zone lymphoma (SMZL); few data are available for extranodal marginal zone lymphoma (EMZL) and nodal marginal zone lymphoma (NMZL). Patients and methods: Incidence and patterns of histologic BM involvement are studied in 120 MZL patients (48 SMZL, 59 EMZL, 13 NMZL) at onset and during follow-up; relationships between clinical features, BM histology and flow cytometry (FC) are analyzed. Results: At diagnosis, BM involvement occurs in 90% SMZL, 22% EMZL and 54% NMZL (P < 0.0001); at reevaluation, incidence raises to 96% in SMZL and 34% in EMZL. Concordance between histology and FC is found in 87% of cases; most discordant cases have positive histology but negative FC. SMZL and EMZL show a nodular BM infiltration; the interstitial pattern is frequent in NMZL (P < 0.0001); sinusoidal localization is typical of SMZL, frequent in NMZL and occasional in EMZL (P = 0.0001). Stage, leukemic disease, B symptoms, more than one extranodal involved site, splenomegaly, elevated b2-microglobulin, serum monoclonal component, International Prognostic Index (IPI) and age-adjusted IPI are directly related to BM infiltration. Conclusions: The different prevalence of BM involvement in MZL subtypes reflects their heterogeneous dissemination modalities; histology seems more sensible than FC to detect BM infiltration; development of BM

Deposition of amyloid in the buttock is a rare complication of dialysis related amyloidosis (DRA), but this localization is even rarer in other types of amyloidoses. We report here the clinical, radiological, and biochemical features of a patient who incurred into this complication after 27 years of hemodialysis. Imaging of the amyloid deposition by magnetic resonance imaging (MRI) documents the amyloid infiltration in the muscles of the buttock region and highlights a peculiar feature of amyloid fibrils deposition in the subcutaneous fat. The amyloid deposition is confirmed by biochemical and microscopic analysis of fibrils extracted from a biopsy specimen. Review of literature and the features of this case lead to speculation that the peculiar involvement of the buttock region including muscles and subcutaneous fat in DRA might derive from the propagation of amyloid initially deposited in the hip joint.

Summary Philadelphia-negative chronic myeloproliferative disorders (CMD) include polycythemia vera (PV), essential thrombocythemia (ET) and primary myelofibrosis (PMF). Angiogenesis is critical in the pathogenesis of PMF. We studied angiogenesis in 115 patients with CMD (23 PV, 24 ET, 46 PMF, 12 post-PV and 10 post-ET myelofibrosis) by assessment of microvessel density (MVD) in bone marrow (BM). Kruskall–Wallis analysis of variance showed that patients with PMF had significantly higher values of MVD than those with PV (P

Between January 1987 and October 1989, 561 consecutive untreated patients with monoclonal gammopathy of undetermined clinical importance (MGUS) (n = 295) or with multiple myeloma (n = 266) were evaluated in a multicentre trial. Both bone marrow biopsy and aspiration (performed at different anatomical sites) were required at presentation. Bone marrow biopsy data indicated that changes in bone marrow composition from MGUS to early multiple myeloma and to advanced multiple myeloma followed a precise pattern, including an increased percentage of bone marrow plasma cells (BMPC%), a shift from plasmocytic to plasmoblastic cytology, an increase in bone marrow cellularity and fibrosis, a change in bone marrow infiltration (becoming diffuse rather than interstitial), a decrease in residual haemopoiesis and an increase in osteoclasts. In multiple myeloma the BMPC% of biopsy specimens and aspirate were closely related, although in 5% of cases the difference between the two values was greater than 20%. Some histological features were remarkably associated with each other. For example, BMPC% was higher in cases with plasmoblastic cytology, heavy fibrosis, or reduced residual haemopoiesis. Anaemia was the clinical characteristic most influenced by bone marrow histology. The BMPC% was the only histological variable which affected the greatest number of clinical and laboratory characteristics, including, besides haemoglobin concentration, erythrocyte sedimentation rate, radiographic skeletal bone disease, and serum concentrations of monoclonal component, calcium, beta 2-microglobulin and thymidine kinase activity. These data indicate that comparative bone marrow histology in monoclonal gammopathies has clinical importance.

Background. Posttransplantation lymphoproliferative disorders (PTLDs) are heterogeneous lymphoid proliferations representing a major complication of solid organ transplant. This study details the clinicopathological and molecular features of 17 B-cell PTLDs observed in a single center series of 988 heart and/or lung transplant recipients. Methods. Cases were classified according to World Health Organization lymphoma classification and tested for Epstein-Barr Virus (EBV), clonality, histogenetic phenotypic (CD10, Bcl-6, MUM1, CD138), and genotypic (immunoglobulin and BCL-6 genes somatic hypermutation) markers. Results. This series of 17 PTLDs included: two B-cell monoclonal polymorphic PTLDs and 15 B-cell monomorphic PTLDs (13 diffuse large B-cell lymphomas [DLBCL] and 2 Burkitt lymphomas [BL]). EBV was detected in 9/17 cases. A monoclonal immunoglobulin variable (IGV) genes rearrangement was documented in 17/17 cases; IGV somatic hypermutation was found in 88% of cases, indicating a prevalent origin from germinal center (GC)-experienced B cells. Using immunophenotypic markers, three histogenetic profiles were identified: a) CD10 + /bcl-6 + /MUM1 - /CD138 - , mimicking GC B-cells; b) CD 10-/bcl-6 + /MUM 1 + /CD 138 -, reminiscent ofB-cells at the latest phases ofGC reaction; and c) CD10-/bcl-6-/MUM1+/CD138±,consistent with preterminally differentiated B-cells. Conclusions. Correlation between morphology, histogenesis, and EBV status demonstrated a high degree of homogeneity in the two GC-related groups, mostly including EBV-negative cases with BL and DLBCL-centroblastic features; the third group, consisting of post GC EBV-positive cases, was histologically less homogeneous, as it included polymorphic PTLDs and DLBCL with immunoblastic and anaplastic features. The EBV-negative cases with GC histogenetic phenotype showed a slightly better outcome; however, such less aggressive prognostic trend was not confirmed by statistical analysis.

Most post-transplant lymphoproliferative disorders (PTLDs) are of B-cell origin, whereas T-cell lymphomas rarely occur. We detail the clinicopathological features of the first case of Epstein-Barr virus (EBV)-associated primary cutaneous CD30+ anaplastic large cell lymphoma (ALCL) in the setting of heart transplant. A 71-year-old patient, 111 months after transplant, presented with multiple cutaneous lesions on the left thigh; histological and immunohistochemical examinations led to diagnosis of T-cell CD30+ ALCL. In situ hybridization demonstrated the presence of EBV-positive tumour cells. The patient received radiotherapy, but he relapsed at the same cutaneous site with loco-regional nodal spread. Chemotherapy was administered resulting in complete remission; four years later the patient is alive and well. Our findings indicate that primary cutaneous EBV+ CD30+ ALCLs should be included within the T-cell PTLDs spectrum; further studies are required to confirm whether they may be also considered, in transplantation settings, a distinct lymphoma subset with relatively favourable outcome.

BACKGROUND Splenic and nodal marginal zone lymphomas (MZL) are subtypes of marginal zone-derived neoplasms. Due to their rarity, little is known concerning their relation, pattern of dissemination, and treatment outcome. METHODS The authors analyzed the clinicopathologic features and outcome of 43 patients (34 patients with splenic MZL and 9 patients with nodal MZL). All lesional tissues obtained at diagnosis were reviewed histologically. RESULTS Among the patients with splenic MZL, 30 patients had Stage IV disease (based on the Ann Arbor staging system). Twenty-six patients presented with splenomegaly with or without limited involvement of abdominal lymph nodes, whereas 7 patients showed disease extension to superficial lymph nodes. Hepatitis C virus (HCV) serology was positive in 35% of patients. Seventeen patients underwent splenectomy, 8 patients received chemotherapy, and 7 patients were followed without initial treatment. Interferon produced a lymphoma response in three of four HCV positive patients. Of 27 treated patients, 13 patients achieved a complete response, and 12 patients achieved a partial response. The median event-free survival (EFS) was 3.3 years (5.1 years for patients with disease confined to the abdomen and 2.1 years for patients with disease extension to superficial lymph nodes). Among nine patients with nodal MZL, four patients had Stage IV disease. HCV serology was positive in two patients. Five patients responded to chemotherapy. The median EFS was 2.8 years. The median overall survival was not reached for patients with both types of MZL. CONCLUSIONS The results of the current study demonstrated that splenic and nodal MZL are indolent lymphomas with different presenting features but common morphologic and biologic characteristics, including high HCV seroprevalence. Studies will be required to identify specific biologic markers and to define the best treatment. Cancer 2004;100:107–15. © 2003 American Cancer Society.

SummaryThe transcription factor GATA-1, together with its cofactor FOG-1, regulates erythropoiesis and megakaryocytopoiesis. Mutations in the DNA or FOG-1 binding sites of its N-terminal zinc finger result in different illnesses. Alterations of the FOG-1 face are responsible for dyserythropoietic anemia with thrombocytopenia while R216Q, the only mutation identified in the DNA face, induces X-linked thrombocytopenia with thalassemia (XLTT). The former disorder has been studied in detail whereas little is known about the latter since only one family has been investigated. We studied a second family with an R216Q, showing that XLTT and dyserythropoietic anemia with thrombocytopenia, even if different clinical entities, are closely related disorders. In both cases, patients present mild dyserythropoiesis, red cell hemolysis, severely defective maturation of megakaryocytes, macrothrombocytopenia with α-granule deficiency, and abnormalities of the cytoplasmic membrane system. However, a thalassemia minor phenotype has only been described in patients with XLTT whereas severe anemia and thrombocytopenia with evident defects of platelet composition and function may be observed only in dyserythropoietic anemia with thrombocytopenia.

Posttransplantation lymphoproliferative disorders (PTLDs) represent a serious complication of solid organ transplantation. This study assessed the molecular histogenesis of 52 B-cell monoclonal PTLDs, including 12 polymorphic PTLDs (P-PTLDs), 36 diffuse large B-cell lymphomas (DLBCLs), and 4 Burkitt/Burkitt-like lymphomas (BL/BLLs). Somatic hypermutation (SHM) of immunoglobulin variable (IgV) genes documented that most monoclonal B-cell PTLDs (75% P-PTLDs, 91.3% DLBCLs, 100% BL/BLLs) derive from germinal center (GC)-experienced B cells. B-cell lymphoma 6 (BCL6) mutations occurred in 25% P-PTLDs, 60.6% DLBCLs, and 75.0% BL/BLLs. A first histogenetic category of PTLDs (31.2% DLBCLs) express the BCL6+/multiple myeloma oncogene-1 protein (MUM1-/+)/CD138- profile and mimic B cells experiencing the GC reaction, as also suggested by ongoing SHM in a fraction of these cases. A second subset of PTLDs (66.7% P-PTLDs and 31.2% DLBCLs) display the BCL6-/MUM1+/CD138- phenotype and mimic B cells that have concluded the GC reaction. A third histogenetic category of PTLDs (25.0% P-PTLDs and 31.2% DLBCLs) shows the BCL6-/MUM1+/CD138+ profile, consistent with preterminally differentiated post-GC B cells. Crippling mutations of IgV heavy chain (IgVH) and/or IgV light chain (IgVL) genes, leading to sterile rearrangements and normally preventing cell survival, occur in 4 DLBCLs and 1 BL/BLL that may have been rescued from apoptosis through expression of Epstein-Barr virus (EBV)-encoded latent membrane protein 1 (LMP1). Overall, the histogenetic diversity of monoclonal B-cell PTLDs may help define biologically homogeneous categories of the disease. (Blood. 2003;102: 3775-3785)

Primary lymphoepithelioma-like carcinoma (LELC) of the lung is a rare tumor that preferentially affects Asian patients, with only 15 cases described in Caucasians to date. Epstein-Barr virus (EBV) infection is present in most lung LELCs in Asians, but it has never been shown in Caucasians. EBV small nuclear RNA and latent membrane protein-1 were identified in the neoplastic cells of primary LELC of the lung diagnosed by endobronchial biopsy in a 25-year-old Italian male. Despite advanced locoregional disease, with neoplastic infiltration of the main right bronchus, the carina, and the pulmonary artery, which prevented surgical resection, partial response and 1-year symptom-free follow-up were achieved after combined chemotherapy and radiotherapy.

Background: Fechtner syndrome (FTNS), also known as Alport-like syndrome, is a rare inherited condition characterized by progressive nephritis, macrothrombocytopenia, Dohle-like leukocyte inclusions, deafness, and cataract. Although it recently was shown that FTNS derives from mutation of MYH9 , the gene for the heavy chain of nonmuscle myosin IIA (NMMHC-IIA), its pathophysiological characteristics remain unknown. Methods: We studied a large FTNS family in which 10 components carried a missense mutation of MYH9 determining the D1424H substitution. Results: All affected subjects presented with macrothrombocytopenia and leukocyte Dohle-like bodies consisting of macroaggregates of NMMHC-IIA, but only two subjects had major renal problems characterized by proteinuria and renal failure. Electron microscopy showed focal and segmental effacement of podocytes and loss of the interpodocyte slit diaphragm. Immunohistochemistry showed apical localization of NMMHC-IIA in tubular epithelia and less podocyte staining in the two patients, whereas it was diffuse in normal epithelia. Three patients presented with stable microhematuria, and another five patients had no renal lesions, although they carried the same mutation of MYH9 . Therefore, MYH9 mutation per se was responsible for platelet and leukocyte abnormalities, whereas additional predisposing conditions and/or environmental factors are necessary for nephropathy, cataract, and deafness. Looking at podocyte components conferring permselectivity properties to the kidney, we characterized the haplotype of podocin and found cosegregation of one specific allele in the two patients with nephrotic syndrome, suggesting a relationship between podocin features and proteinuria. Conclusion: Our study indicates a major role for the NMMHC-IIA abnormality in the pathogenesis of leukocyte, platelet, and kidney defects in FTNS. The basic feature in all cases is aggregation and compartmentation of NMMHC-IIA. However, proteinuria and podocyte lesions are the hallmark of nephropathy in patients who develop renal failure, and podocin may have some function in this setting. Am J Kidney Dis 41:95-104. © 2003 by the National Kidney Foundation, Inc.

This study analyzes the pathologic and molecular features of 5 cases of primary cutaneous large B-cell lymphoma of the leg (PCLBCL-leg), recently included in the European Organization for Research and Treatment of Cancer (EORTC) classification of primary cutaneous lymphoma. PCLBCL-leg accounts for 5% to 10% of all primary cutaneous B-cell lymphoma (PCBCL), usually affects elderly patients and carries a worse prognosis than other forms of PCBCL. It has been proposed that the malignant cells of PCLBCL-leg originate from germinal center (GC)-related cells, but their effective normal counterpart is unclear, and the rationale behind the inclusion of this lymphoma as a separate entity is based on its prognosis rather than on its proved histogenesis. All of our cases of PCLBCL-leg morphologically resembled diffuse large B-cell lymphoma (DLBCL), but to better define their histogenesis, we also analyzed various phenotypic and genotypic markers, including mutations of the Ig and of BCL,6 genes, as well as expression of the bcl-6, MUM1, and CD138/syndecan-1 proteins. Immunohistochemically, all of our cases stained for the 1,26/CD20cy and CD79a antigens and expressed the bcl-2, bcl-6, and MUM-1 proteins but were negative for both the CD10/CALLA and CD138 antigens. With respect to molecular analysis, the lymphoma population of all PCLBCL-leg carried hypermutation of Ig genes, and all but I case also harbored mutations of the BCL-6 gene. Our results indicate that PCLBCL-leg are similar both under the morphofunctional and molecular profiles to most DLBCL of other sites. Thus, caution seems justified before definitely considering PCLBCL of the leg as a distinct entity. Copyright 2002, Elsevier Science (USA). All rights reserved.

Prefibrotic myelofibrosis (pre-MF) is a prodromic variant of primary myelofibrosis (PMF) characterized by prevalence of female sex, young age, high frequency of splanchnic vein thrombosis and indolent disease course (Barosi et al, PLoS One. 2012;7(4):e35631). Here we report the molecular characteristics at diagnosis of 177 consecutive pre-MF patients included in the institutional data-base of PMF patients at the Center for the Study of Myelofibrosis in Pavia from January 2001 through July 2013. As compared with patients with fibrotic type-MF (bone marrow (BM) fibrosis= 1 to 3), the frequency of JAK2V617F mutation in pre-MF patients (BM fibrosis=0) was higher (69.2% vs. 60.9%; P=0.02) but the JAK2V617F allele burden was lower (39% vs. 50.6%; P= Disclosures: No relevant conflicts of interest to declare.

In 1981 Weemaes et al. first described the Nijmegen breakage syndrome (NBS), a rare autosomal recessive disorder characterized by stunted growth, microcephaly, immunodeficiency, spontaneous chromosome instability, and a peculiar predisposition to cancer development. Most NBS-related malignancies are lymphomas, but their pathologic features have rarely been specified. We report here the case of a northern Italian 8-year-old child who, 2 years after the diagnosis of NBS, developed a diffuse large B-cell lymphoma (T cell–rich B-cell lymphoma variant). The histological and immunobiological features of the lymphoma population are analyzed and discussed in detail.

Mediastinal B-cell lymphoma (MBL) is a distinct variant of aggressive non-Hodgkin's lymphoma with characteristic clinical and biological features but less well-defined histomorphology. We reevaluated 124 biopsy specimens from 109 MBL patients of an Italian/French/German retrospective clinical study. MBL was primarily diagnosed on clinical and histological grounds in conjunction with the detection of CD20 expression by immunohistology. Cytologically, MBL features limited intralesional but considerable interindividual cytological diversity, ranging from medium-sized to very large, atypical cells. Sclerosis and necrosis are restricted to extrathymic and extranodal sites of involvement, predominantly the lung, as is angioinvasion, which predominantly affects larger vessels. The medium-sized and the large cell variants resemble marginal zone lymphoma variants, whereas the very large cell variant of MBL has not so far been found to have any extramediastinal counterpart. We conclude that MBL displays a broad morphological spectrum covering more than is implied by the term “diffuse large cell lymphoma.” Because statistical analysis of cytological and histological criteria failed to correlate with prognosis in this comprehensive group of patients, we think it inadvisable further to subclassify MBL.

The spectrum of CD30+ cutaneous lymphoproliferative disorders is characterized by the histology of a high-grade lymphoma but frequent clinical regression of skin lesions in lymphomatoid papulosis (LyP) and occasional regression in CD30+ large cell lymphomas (LCLs). A recent study shows that apoptosis may be a significant mechanism of regression of LyP (Arch Dermatol 133:828-833, 1997). Therefore, we studied expression of proteins that induce apoptosis, including CD27, CD40, CD95, and nerve growth factor receptor (NGF-R), as well as anti-apoptotic protein bcl-2 in skin lesions from 25 patients within the spectrum of CD30+ cutaneous lymphoma. Our results show consistent expression of CD95 (APO-1/Fas), but rare or absent expression of CD27, CD40, and NGF-R on tumor cells from both regressing LyP lesions and nonregressing CD30+ lymphomas. Bcl-2 was expressed at low levels in LyP and at high levels in pleomorphic CD30+ lymphomas. These results indicate that, in addition to CD30, CD95 expression is preferentially expressed at high levels in all cutaneous CD30+ lymphomas and suggest that CD95 may play a role in the regression of CD30+ skin lesions. Expression of bcl-2 appears to protect tumor cells from apoptosis in CD30+ lymphoproliferative disorders.

The t(2;5)(p23;q35) translocation associated with CD30-positive anaplastic large cell lymphoma results in the production of a NPM-ALK chimeric protein, consisting of the N-terminal portion of the NPM protein joined to the entire cytoplasmic domain of the neural receptor tyrosine kinase ALK. The ALK gene products were identified in paraffin sections by using a new anti-ALK (cytoplasmic portion) monoclonal antibody (ALKc) that tends to react more strongly than a previously described ALK1 antibody with the nuclei of ALK-expressing tumor cells after microwave heating in 1 mmol/L ethylenediaminetetraacetic acid buffer, pH 8.0. The ALKc monoclonal antibody reacted selectively with 60% of anaplastic large cell lymphoma cases (60 of 100), which occurred mainly in the first three decades of life and consistently displayed a T/null phenotype. This group of ALK-positive tumors showed a wide morphological spectrum including cases with features of anaplastic large cell lymphoma “common” type (75%), “lymphohistiocytic” (10%), “small cell” (8.3%), “giant cell” (3.3%), and “Hodgkin’s like” (3.3%). CD30-positive large anaplastic cells expressing the ALK protein both in the cytoplasm and nucleus represented the dominant tumor population in the common, Hodgkin’s-like and giant cell types, but they were present at a smaller percentage (often with a perivascular distribution) also in cases with lymphohistiocytic and small cell features. In this study, the ALKc antibody also allowed us to identify small neoplastic cells (usually CD30 negative) with nucleus-restricted ALK positivity that were, by definition, more evident in the small cell variant but were also found in cases with lymphohistiocytic, common, and “Hodgkin’s-like” features. These findings, which have not been previously emphasized, strongly suggest that the neoplastic lesion (the NPM-ALK gene) must be present both in the large anaplastic and small tumor cells, and that ALK-positive lymphomas lie on a spectrum, their position being defined by the ratio of small to large neoplastic cells. Notably, about 15% of all ALK-positive lymphomas (usually of the common or giant cell variant) showed a cytoplasm-restricted ALK positivity, which suggests that the ALK gene may have fused with a partner(s) other than NPM. From a diagnostic point of view, detection of the ALK protein was useful in distinguishing anaplastic large cell lymphoma cases of lymphohistiocytic and small cell variants from reactive conditions and other peripheral T-cell lymphoma subtypes, as well as for detecting a small number of tumor cells in lymphohemopoietic tissues. In conclusion, ALK positivity appears to define a clinicopathological entity with a T/null phenotype (“ALK lymphomas”), but one that shows a wider spectrum of morphological patterns than has been appreciated in the past.

We describe the clinicopathologic features of an unusual case of CD30+/CD56+ T-cell lymphoma in a child who presented with simultaneous primary extranodal cutaneous and bone localizations. The expression of CD56 (neural cell adhesion molecule, or NCAM) is rare in non-Hodgkin's lymphomas other than in a group of haematopoieticllymphoid neoplasms of natural killer and natural killer-like T cells, which usually involve extranodal sites and often pursue an aggressive clinical behavior. Coexpression of CD30 and CD56 in T-cell lymphomas is exceedingly rare, and its biological significance is unknown. Our patient responded well to an intensive chemotherapy regimen, and she is now in complete remission 4 years after discontinuation of chemotherapy. Expression of NCAM could be regarded as responsible, in part, for the extranodal localization of lymphoma cells: expression of CD56 also might contribute to the definition of a subset of CD30+ lymphomas with distinctive clinicopathologic features.

Sinus histiocytosis with massive lymphadenopathy (SHML), or Rosai-Dorfman disease, is rare histiocytic disorder of known origin which shares several cell markers with Langerhans' cell histiocytosis (LCH). Although Rosai-Dorfman cells exhibit an aberrant immunophenotype, the indolent clinical course of SHML suggests a reactive disorder rather than a neoplastic process. Until recently this was prevailing opinion concerning LCH also, but recent studies have detected clonal histiocytes in all forms of this latter condition, which is therefore considered a clonal neoplastic disorder with highly variable biological behaviour. To determine whether the histiocytic proliferation in SHML is polyclonal or clonal we used X-linked polymorphic loci to assess clonality in lesional tissues in two women. Polymorphic regions of the human androgen receptor (HUMARA) locus were amplified by polymerase chain reaction (PCR) analysis. The HUMARA locus was informative in both cases and, following digestion with methylation-sensitive enzymes, typical polyclonal X-inactivation patterns were observed. Since abnormal cells accounted for > 90% lesional tissue cells, we conclude that Rosai-Dorfman histiocytic proliferation was polyclonal in the women studied.

Abstract 1743 Background: WHO diagnostic criteria of myeloproliferative neoplasms (MPNs) identify a preMF variant including patients having absence or early grade fibrosis, dual myeloid and megakaryocytic dominance, and clusters of atypical, ectopic, variable in size megakaryocytes in the bone marrow (BM). Many issues on the variant are critical, such as its distinction from essential thrombocythemia, recognisability, biological identity and true place among MPNs. Here we describe the clinical presentation of patients with preMF collected among a large cohort of patients diagnosed with PMF according WHO and for whom long-term follow-up data were available. The aim is to investigate whether there is an underlying structure of the patients' characteristics that allows to assign them to a distinct variant of MPNs or to align them along a continuum in the realm of PMF. Methods: We included in this study patients with PMF who were referred to the Center for the Study of Myelofibrosis of IRCCS Policlinico S. Matteo Foundation, Italy from 1990 to 2011. In all patients the BM biopsy taken at diagnosis was reviewed (pathologist: UM) and the diagnosis of preMF was established adopting the stringent criterion that, besides typical BM cellularity and megakaryocyte morphology, BM had less than grade 1 reticulin fibrosis (EUMNET criteria). Results: Of the 659 patients with PMF, 126 fulfilled the criteria we established for the diagnosis of preMF, thus accounting for 19.1% of the cohort. Female sex accounted for 59.5% of the preMF cohort while it accounted for 33.8% of PMF fibrotic type (P In order to assign patients with PMF to groups with different degrees of BM fibrosis, we further categorized MF fibrotic type into early MF (BM fibrosis grade 1) and advanced MF (BM fibrosis grade 2 or 3). Female frequency steadily varied from 59.5% to 43.2% and 25.6% in the 3 categories of BM fibrosis, respectively. Age varied from 39.2, 50.4, 57.0 years, respectively. Hemoglobin and platelet count steadily decreased (Hb=14.0, 13.3, 11.2 g/dL, respectively; platelet count=647, 554, 346 x109/L, respectively). Spleen size steadily increased along with increasing of BM fibrosis (spleen index=120, 152, 200). All these parameters exhibited a statistically significant trend along the continuum of BM fibrosis grade (ANOVA, P Conclusions: The BM picture of preMF identifies a group of patients with PMF associated with a very indolent hematologic phenotype, female dominance and very young age at presentation characterized by high incidence of splanchnic vein thrombosis. Disclosures: Barosi: Novartis: Membership on an entity's Board of Directors or advisory committees.

Little is known about the nature of the large intrasinusoidal cells exhibiting cytophagocytosis, which are the histologic hallmark of sinus histiocytosis with massive lymphadenopathy (SHML) (Rosai-Dorfman disease). Using a broad panel of monoclonal and polyclonal antibodies, we analyzed the immunophenotype of the cell infiltrates in seven lymph node biopsy specimens from five cases of SHML. The SHML cells constantly expressed the S-100 protein, concanavalin agglutinin and peanut agglutinin lectins, and monocyte-macrophage-associated antigens CD 11c, CD 14, CD 33, CD 68, and LN 5. Labeling with other antimacrophage antibodies was extremely variable, with some (MAC 387, lysozyme) restricted to clusters of SHML cells and others (CD 11b, CD 36, alpha-1-antichymotrypsin) staining only sscattered cells. The CD 1a antigen was found on some cells in only one case, whereas HLA-DR and the HLA-DR-associated invariant chains were absent. The heterogeneity of SHML cell marker expression might be related to the local content of factors (eg, cytokines) capable of modulating the phenotype of monocytes and derived cells. All cases presented with huge amounts of medium-sized mononuclear cells accumulated in the sinuses and intersinusoidal tissue. These cells expressed the S-100-/CD 11b+/CD 11c+/CD 14+/CD 16+/CD 33+/CD 36+/lysozyme+/MAC 387+/HLA-DR+ phenotype. These recently immigrated monocytes might represent the immediate precursors of SHML cells.

Histochemical and immunohistochemical studies performed in only a few cases of sinus histiocytosis with massive lymphoadenopathy (SHML) indicated that SHML cells belong to the macrophage--histiocyte system, though their exact origin is still uncertain. We analyzed the morphological, antigenic and enzymatic characteristics of the histiocyte-like cells in one paediatric case of SHML (also named Rosai-Dorfman disease). The SHML cells expressed the S-100 protein, lectins concanavalin A, peanut agglutinin and monocyte-macrophage related antigens CD 11c, CD 14, CD 33, CD 68 and LN 5. Reactivity with other anti-macrophage antibodies (MAC387, lysozyme, alpha-1 anti-chymotrypsin) was variable. The CD1a antigen was present only in scattered cells, whereas HLA-DR and the HLA-DR associated invariant chain were absent. Cytochemistry demonstrated an intense activity of acid phosphatase and non specific esterase of SHML cells. A large amount of medium sized mononuclear cells were located in the sinuses and intersinusoidal tissue. Our findings suggest that SHML cells have intermediate features between phagocytes and Langerhans cells/interdigitating reticulum cells. The heterogeneity of marker expression on SHML cells might be related to the local content of factors (e.g., cytokines), capable of modulating the phenotype of monocyted and derived cells.