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Eosinophilic phenotypes in polycythemia vera (PV) and essential thrombocythemia (ET) are rare and poorly characterized. Co-occurring JAK2 mutations in cis, specifically L611S or N622Y mutations, appear to result in a more aggressive clinical phenotype. PV/ET with eosinophilic phenotypes may require full next-generation sequencing to capture co-occurring mutations as opposed to more prevalent single-gene assays. These eosinophilic phenotypes are highly thrombotic and systemic symptoms appear responsive to early use of the janus kinase inhibitor ruxolitinib.

Myelodysplastic syndrome (MDS) is characterized by persistent cytopenias and evidence of morphologic dysplasia in the bone marrow (BM). Excessive hematopoietic programmed cell death (PCD) and inflammation have been observed in the bone marrow of patients with MDS, and are thought to play a significant role in the pathogenesis of the disease. Necroptosis is a major pathway of PCD that incites inflammation; however, the role of necroptosis in human MDS has not been extensively investigated. To assess PCD status in newly diagnosed MDS, we performed immunofluorescence staining with computational image analysis of formalin-fixed, paraffin-embedded BM core biopsies using cleaved caspase-3 (apoptosis marker) and necroptosis markers (receptor-interacting serine/threonine-protein kinase 1 [RIPK1], phospho-mixed lineage kinase domain-like protein [pMLKL]). Patients with MDS, but not controls without MDS or patients with de novo acute myeloid leukemia, had significantly increased expression of RIPK1 and pMLKL but not cleaved caspase-3, which was most evident in morphologically low-grade MDS (5% BM blasts) and in MDS with low International Prognostic Scoring System risk score. RIPK1 expression highly correlated with the distribution of CD71

Diagnosis, classification, and requisite ancillary studies (flow cytometry, cytogenetics, and molecular genetics) of acute myeloid leukemia, critical to optimal patient care, have changed dramatically in the last 15 years and continue to evolve at a rapid pace. We present in this chapter background information for understanding these changes to date, review current diagnosis and classification of these diseases, and provide insights into future possible evolution of our understanding of the biology of this set of diseases.

Objectives To assess bone marrow (BM) sampling in academic medical centers. Methods Data from 6,374 BM samples obtained in 32 centers in 2001 and 2011, including core length (CL), were analyzed. Results BM included a biopsy (BMB; 93%) specimen, aspirate (BMA; 92%) specimen, or both (83%). The median (SD) CL was 12 (8.5) mm, and evaluable marrow was 9 (7.6) mm. Tissue contraction due to processing was 15%. BMB specimens were longer in adults younger than 60 years, men, and bilateral, staging, and baseline samples. Only 4% of BMB and 2% of BMB/BMA samples were deemed inadequate for diagnosis. BM for plasma cell dyscrasias, nonphysician operators, and ancillary studies usage increased, while bilateral sampling decreased over the decade. BM-related quality assurance programs are infrequent. Conclusions CL is shorter than recommended and varies with patient age and sex, clinical circumstances, and center experience. While pathologists render diagnoses on most cases irrespective of CL, BMB yield improvement is desirable.

Anaplastic large cell lymphoma (ALCL) is a lymphoma of T-cell origin, characterized by the presence of large lymphoid cells with abundant cytoplasm and pleomorphic, often horseshoe-shaped nuclei (hallmark cells), as well as strong and uniform expression of cluster of differentiation (CD)30. Two distinct clinicopathologic categories of ALCL include primary cutaneous ALCL and systemic ALCL. Systemic ALCL is further classified into anaplastic lymphoma kinase (ALK)-positive, ALK-negative, and breast implant-associated ALCL. Most ALCLs occurring in adults are ALK negative and present in lymph nodes rather than extranodal sites.Primary diagnosis of ALCL in the pleural fluid is extremely rare, with no convincing recent reports available that are based in current understanding of this entity. Herein, we describe a well-characterized case of ALK-negative ALCL with no rearrangement but amplification of DUSP22/IRF4, diagnosed by cytologic examination of the pleural effusion in a 68-year-old white man with a 3-year history of unexplained eosinophilia and pulmonary infiltrates. Also, we present a review of the literature and discuss the current understanding of ALCL based on the 2016 revision of the World Health Organization (WHO) classification of lymphoid neoplasms.

Introduction ALK-negative anaplastic large cell lymphoma (ALK- ALCL) is an uncommon type of T-cell non-Hodgkin lymphoma (T-NHL) with worse prognosis compared to ALK-positive (ALK+) ALCLs. Most published studies on the genomics of T-NHL have focused on peripheral T-cell lymphoma, not otherwise specified (PTCL-NOS), and previous studies of ALCL described rearrangements in DUSP22 and TP63 and mutations in genes comprising the JAK/STAT pathway as common genetic drivers in ALK- ALCL. The degree to which these drivers affect survival or other molecular features of ALK- ALCL remains unknown. Here, we describe novel subgroups of ALK- ALCL that exhibit distinct survival. One subgroup appears molecularly similar to ALK+ALCLs and is associated with favorable survival while the second subgroup is quite distinct from ALK- ALCLs and associated with poor outcomes. Methods and Results Eighty-two ALK- ALCL patients were recruited to the Atlas of Blood Cancer (ABC) genomes project, a worldwide consortium established to define the molecular origins of blood cancers. Tumor biopsies from these patients, as well as 10 ALK+ ALCL samples for comparison were obtained from participating institutions. Each case was subjected to centralized pathology review by an experienced panel of hematopathologists to ensure the accuracy of the diagnosis. All cases, along with paired normal tissues, were subjected to DNA and RNA (whole exome-level) sequencing on the Illumina platform to identify mutations and expression changes for each of these cases using methods well established in our group and described previously. We first examined the genetic alterations in ALK- ALCLs. In addition to frequently described genetic alterations such as TP63 and DUSP22 rearrangements, as well as mutations in JAK1, STAT3 and TP53, we also detected mutations in ERBB4, SETD2 and KMT2D, which may serve as potential novel drivers and have not been described previously to our knowledge. We next performed comparative gene expression analysis of the ALK- and ALK+ ALCLs. Surprisingly, a proportion of ALK- ALCL cases (38%) clustered together with ALK+ ALCLs and had a signature resembling ALK+ cases, which we designated as "ALK-like ALCL" here. Both the ALK-like ALCLs and the other ALK- ALCL cases showed decreased ALK expression compared to the ALK+ ALCLs by gene expression analysis. These results point to downstream pathways that are common among ALK+ALCLs and ALK-like ALCLs, but different from the other ALK- ALCLs. Gene set enrichment analysis revealed that the ALK-like ALCLs overexpressed genes in pathways related to monocyte and fibroblast activation, whereas the remaining ALK- ALCLs overexpressed genes in the T follicular helper cells, memory T cells and adaptive immune response-related pathways (P Conclusion Our data indicate that ALK- ALCLs represent a heterogeneous group of diseases and comprise at least two distinct subgroups that can be identified based on their similarity to the ALK+ ALCLs. The ALK-like ALCLs demonstrated distinct molecular features and favorable outcomes. Our results provide a potentially new approach to patient risk-stratification and pathological classification of this disease. Disclosures Kwong: Celgene: Consultancy, Honoraria, Research Funding; Bayer: Consultancy, Honoraria, Research Funding; Astellas: Consultancy, Honoraria, Research Funding; Amgen: Consultancy, Honoraria, Research Funding; Bristol Myers Squibb: Consultancy, Honoraria, Research Funding; BeiGene: Consultancy, Honoraria, Research Funding; Gilead: Consultancy, Honoraria, Research Funding; Janssen: Consultancy, Honoraria, Research Funding; Merck: Consultancy, Honoraria, Research Funding; Novartis: Consultancy, Honoraria, Research Funding; Roche: Consultancy, Honoraria, Research Funding; Takeda: Consultancy, Honoraria, Research Funding. Jaye: Stemline Therapeutics: Honoraria. Behdad: Roche/Foundation Medicine: Speakers Bureau; Thermo Fisher: Speakers Bureau; Lilly: Speakers Bureau. Hsi: AbbVie Inc, Eli Lilly: Research Funding. Dave: Data Driven Bioscience: Current equity holder in publicly-traded company.

Introduction Blood cancers are collectively common and strikingly heterogeneous diseases both clinically and molecularly. According to the WHO taxonomy, there are over 100 distinct myeloid and lymphoid neoplasms. Genomic profiling of blood cancers has been applied in a somewhat ad hoc fashion using diverse sequencing approaches including the use of targeted panels, whole exome sequencing, whole genome sequencing, RNA sequencing, etc. The lack of data uniformity has made it difficult to comprehensively understand the clinical and molecular spectrum within and across diseases. Systematic genomic approaches can address the central challenges in the diagnosis and treatment of blood cancers. For the diagnosis of blood cancers, the incorporation of genomics could greatly enhance the accuracy and speed of clinical diagnostics. Genomics could also inform their pathology classification. However, these applications must be preceded by a clear understanding of the particular genetic aberrations and expression profiles that unite and distinguish different leukemias and lymphomas. Therapeutic development can also be aided by genomic approaches through identification of new targets and establishing the relevance of existing targets and treatments. Targeted therapies including those directed at specific surface markers (e.g. CD19, CD30 and CD123) or molecular targets (e.g. BCR-ABL fusions, IDH1 mutations and EZH2 mutations) are rarely restricted to a single disease, with most occurring in multiple blood cancers. A systematic understanding of the presence or overlap of these targets within or across blood cancers would significantly expand the therapeutic possibilities and better enable the use of existing therapies in both common and rare cancers. However, such therapeutic possibilities need to be established through a rigorous, data-driven approach. We initiated the Atlas of Blood Cancers Genomes (ABCG) project to systematically elucidate the molecular basis of all leukemias and lymphomas by building upon advances in genomic technologies, our capabilities for data analysis and economies of scale. Using a uniform approach to systematically profile all blood cancers through DNA and RNA sequencing at the whole exome/whole transcriptome level, we aim to link genomic events with clinical outcomes, disease categories and subcategories, thereby providing a complete molecular blueprint of blood cancers. Methods/Results The ABCG project consists of collaborators from 25 institutions around the world who have collectively contributed samples from 10,481 patients comprising every type of blood cancer in the current WHO classification. The samples include thousands of myeloid leukemias and mature B cell lymphomas, hundreds of Hodgkin lymphoma and plasma cell myeloma, as well as every rare type of hematologic malignancy (along with case-matched normal tissue). All cases were de-identified and their associated pathology and detailed clinical information entered into a purpose-built web-based system that included disease-specific data templates. All cases were subjected to centralized pathology review and clinical data review by experienced hematopathologists and oncologists. All 10,481cases are being sequenced at the DNA and RNA level, and are being profiled to define the genetic alterations and expression changes that are characteristic of each disease. Analysis will include translocations, copy number alterations, and viral status. These molecular features will be examined in conjunction with genetic events, pathologic factors, and the clinical features. We have already generated results for ALK-negative anaplastic large B cell lymphoma and primary mediastinal B cell lymphomas (N=210). These data demonstrate novel subgroup and molecular discoveries that are enabled by integrative DNA and RNA sequencing analysis and the examination of molecular features across different diseases as well as within individual entities. In addition, other disease entities and the collective data will be presented in the meeting. Conclusion The ABCG project will comprehensively study the genetic and clinicopathological features of all blood cancers using systematic genomic approaches. We anticipate our data, approaches and results will serve as a lasting resource for the molecular classification and therapeutic development for leukemias and lymphomas. Disclosures McKinney: Novartis: Research Funding; Nordic Nanovector: Research Funding; Molecular Templates: Consultancy, Research Funding; Kite/Gilead: Honoraria, Speakers Bureau; Incyte: Research Funding; Genetech: Consultancy, Honoraria, Research Funding; Epizyme: Consultancy; Celgene: Consultancy, Research Funding; BTG: Consultancy; Beigene: Research Funding; ADC Therapeutics: Consultancy, Speakers Bureau; Pharmacyclics: Consultancy; Verastem: Consultancy. Behdad: Lilly: Speakers Bureau; Roche/Foundation Medicine: Speakers Bureau; Thermo Fisher: Speakers Bureau.

Introduction: Primary mediastinal large B-cell lymphoma (PMBL) is a rare non-Hodgkin lymphoma subtype that occurs predominantly in young adults, with an overall favorable prognosis. The cell of origin is presumed to be thymic medullary B-cells and the gene expression profile of PMBL is similar to classic Hodgkin lymphoma. Recent studies have begun unravelling the genomic alterations underlying PMBL. Frequent, recurrent mutations (e.g. B2M, TNFAIP3, SOCS1, STAT6, GNA13) have been reported, but most of the studies have analyzed a small number of cases. To gain further insights into disease biology, we recruited 63 cases of PMBL as part of the Atlas of Blood Cancer Genomes (ABC-G) initiative, a consortium consisting of 25 institutions. Methods: Formalin-fixed paraffin-embedded (FFPE) biopsies and clinical data were collected. All cases were subjected to centralized review by an experienced panel of hematopathologists to ensure accurate diagnosis. Whole-exome DNA and RNA sequencing was performed using the Illumina platform and the DNA and RNA reads aligned to the GRCh38 genome and transcriptome respectively. Exonic variants were filtered using a set of paired normal samples and population-based databases to identify putative driver mutations, which were then aggregated at the gene level. Mutational analysis was performed on 56 samples that passed quality filtering and expression analysis on 45 samples. RNAseq data was normalized using DESeq2. Results: The cohort included samples from 16 males and 24 females, with a median age of 33 years (range 16 - 72) at the time of diagnosis. The majority of patients were treated with R-CHOP (47%) or R-EPOCH (43%), with 93% of patients surviving through the end of follow-up (median follow-up: 60.1 months). Besides the known recurrent mutations involving the JAK-STAT (STAT6 -21%, SOCS1 - 26%), NFKB (TNFAIP3 - 27%, NFKB1A - 7%), immune escape (B2M - 20%, LTB - 11%, IRF8 - 9%, IRF4 -9%), and chromatin modification (ZNF217 - 16%, CREBBP - 11%, KMT2D -11%) pathways , we discovered recurrent somatic variants in novel candidate driver genes in this disease, including NOTCH4 (7%), DICER1 (11%), MCL1 (7%), amongst others. EZH2, EP300, and XPO1 mutations were not detected. CIITA mutations and fusions were observed in 14% and 11% of cases, respectively, with novel partner genes (IGHA2, IGHG1, CDC6) detected in 67% of the fusion positive cases. Copy number alterations included gains at 2p16.1 (REL - 20%) and 9p24.2 (JAK2/PDL1/PDL2 - 24%), as well as loci not previously implicated in PMBL, 8q24.3 and 9q34.3 (each in 20%). Of note, CIITA alterations and 9p24 gains were virtually mutually exclusive, highlighting diverse mechanisms of immune escape in this entity. The transcriptomes of cases harboring CIITA alterations demonstrated differential enrichment of genes involved in protein glycosylation. The PMBLs in our series showed significant enrichment of the reported PMBL genetic classifier score, compared to nodal diffuse large B cell lymphoma (DLBCL) (p=0.0003). Finally, the gene expression profile of thymic B cells was more similar to that of PMBL than nodal DLBCL (p=0.0144). Conclusions: Our study, representing one of the largest comprehensive genomic and transcriptomic analyses of PMBL, expands the mutational landscape of PMBL, provides evidence for biologically distinct disease subsets and suggests an origin of PMBLs from thymic B-cells. Disclosures Hsi: AbbVie: Research Funding; Eli Lilly: Research Funding; Cytomx: Honoraria; Seattle Genetics: Honoraria. McKinney: BTG: Consultancy; Celgene: Consultancy, Research Funding; Epizyme: Consultancy; Genetech: Consultancy, Honoraria, Research Funding; Incyte: Research Funding; Kite/Gilead: Honoraria, Speakers Bureau; Molecular Templates: Consultancy, Research Funding; Nordic Nanovector: Research Funding; Novartis: Research Funding; Pharmacyclics: Consultancy; Verastem: Consultancy; Beigene: Research Funding; ADC Therapeutics: Consultancy, Speakers Bureau. Jaye: Stemline Therapeutics: Honoraria. Cohen: Genentech, Takeda, BMS/Celgene, BioInvent, LAM, Astra Zeneca, Novartis, Loxo/Lilly: Research Funding; Janssen, Adaptive, Aptitude Health, BeiGene, Cellectar, Adicet, Loxo/Lilly, AStra ZenecaKite/Gilead: Consultancy. Behdad: Lilly: Speakers Bureau; Roche/Foundation Medicine: Speakers Bureau; Thermo Fisher: Speakers Bureau. Dave: Data Driven Bioscience: Current equity holder in publicly-traded company.

OBJECTIVES: To assess bone marrow (BM) sampling in academic medical centers. METHODS: Data from 6,374 BM samples obtained in 32 centers in 2001 and 2011, including core length (CL), were analyzed. RESULTS: BM included a biopsy (BMB; 93%) specimen, aspirate (BMA; 92%) specimen, or both (83%). The median (SD) CL was 12 (8.5) mm, and evaluable marrow was 9 (7.6) mm. Tissue contraction due to processing was 15%. BMB specimens were longer in adults younger than 60 years, men, and bilateral, staging, and baseline samples. Only 4% of BMB and 2% of BMB/BMA samples were deemed inadequate for diagnosis. BM for plasma cell dyscrasias, nonphysician operators, and ancillary studies usage increased, while bilateral sampling decreased over the decade. BM-related quality assurance programs are infrequent. CONCLUSIONS: CL is shorter than recommended and varies with patient age and sex, clinical circumstances, and center experience. While pathologists render diagnoses on most cases irrespective of CL, BMB yield improvement is desirable.

Background Common minimally invasive methods for acquiring samples for flow cytometric immunophenotyping (FCI) include fine-needle aspiration (FNA) and needle core biopsy (NCB). FCI requires a sufficient quantity of viable cells for adequate evaluation. Methods We collected patient data from our files of all FCI cases sampled via FNA or NCB from January 1, 2003 and June 1, 2012. Total Viable Cells (TVC) was calculated by multiplying the volume, viability, and concentration and then converted to logarithmic scale as “Log TVC.” Statistical analysis was performed using SPSS. Results Five hundred seventy-one FCI cases at our institution were reviewed covering the period from 2003 to 2012 and 456 total cases were analyzed. One hundred sixteen cases were sampled by NCB and 340 were sampled by FNA. Comparing FNA to NCB subgroups demonstrated FNA to be superior in mean specimen viability, TVC, and cases with a final FCI interpretation. The cellularity of the sample (in Log TVC) correlates with the likelihood of achieving a FCI interpretation. The point where at least 50% of cases have a diagnostic FCI interpretation occurs between Log TVC of 5.0–5.25. However, FNA based cases had a higher proportion of samples with an indeterminate final diagnosis. Conclusions FNA was found to be significantly superior to NCB in obtaining material for FCI. However, NCB resulted in fewer indeterminate final diagnoses due to benefit of histologic correlation. In our opinion, NCB for histology combined with dedicated FNA material for FCI may yield the best results for a minimally invasive approach to the diagnosis of hematologic neoplasms. © 2014 International Clinical Cytometry Society

AimsLymphocytosis is commonly encountered in the haematology laboratory. Evaluation of blood films is an important screening tool for differentiating between reactive and malignant processes. The optimal lymphocyte number to trigger morphological evaluation of the smear has not been well defined in the literature. Likewise, the significance of lymphocyte morphology has not been well studied and there are no consensus guidelines or follow-up recommendations available. We attempt to evaluate the significance of lymphocyte morphology and to define the best possible cut-off value of absolute lymphocyte count for morphology review.Methods71 adult patients with newly detected lymphocytosis of 5.0×109/L or more were categorised to either a reactive process or a lymphoproliferative disorder. We performed statistical analysis and morphology review to compare the difference in age, gender, lymphocyte count and morphological features between the two groups. Receiver operating characteristic analysis was performed to determine an optimal lymphocyte number to trigger morphology review.ResultsLymphoproliferative disorders are associated with advanced age and higher lymphocyte count. Sensitivity, specificity, positive predictive value, negative predictive value and accuracy of lymphocyte morphology as a screening test were 0.9, 0.59, 0.60, 0.58 and 0.71, respectively. The optimal cut-off of lymphocyte number for morphology review was found to be close to 7×109/L.ConclusionsWe found a moderate interobserver agreement for the morphological assessment. ‘Reactive’ morphology was very predictive of a reactive process, but ‘malignant’ morphology was a poor predictor of a lymphoproliferative disorder.

Follicular Lymphoma (FL) is the most common indolent lymphoma derived from light zone germinal center B cells and characterized by a t(14;18) translocation resulting in upregulation of BCL2 in over 80% of cases. This translocation alone is not sufficient for tumorogenesis, and must be combined with additional genetic mutations to transform B cells. FL is incurable and the disease course can be highly varied, with survival ranging from a few months to decades following diagnosis and treatment with standard chemoimmunotherapy. The heterogeneity of FL poses major challenges to identifying the association of genetic alterations and clinical outcome. Current WHO guidelines recommend establishing grade for each FL case with grade 3 thought to be more aggressive than 1 and 2. The genetic basis and clinical implications of grade in FL are unclear. Recent sequencing studies have identified many genes found to be recurrently mutated in FL including KMT2D and CREBBP. However, the degree to which genetic alterations cooperate with each other or contribute to clinical outcome is unclear. Based on the observed mutational rates in follicular lymphoma, we estimated 900 cases were needed to comprehensively delineate the genetic alterations that underlie histologic grade and clinical outcome. Accordingly, we enrolled a cohort of 1042 patients with newly diagnosed FL. All treated patients received rituximab-containing standard regimens. To go beyond the identification of gene-coding events, we developed a very large panel of 110 Mbp covering exonic (~40Mbp) and non-exonic regions (~70Mbp) of interest to enable a wide range of genomic analysis including mutation calling in both coding and non-coding regions, rearrangement detection, viral identification, and copy number analysis. In addition to the whole exome, we extended coverage to include introns, promoters, and untranslated regions of all known driver genes in cancer. We included the entirety of the immunoglobulin loci, T-cell receptor loci and CD3 loci to detect clonotypes and rearrangements. We also included lymphoma-relevant long non-coding RNAs, microRNAs, enhancers, and breakpoint-prone regions. For viral detection, we targeted the genomes of eight cancer-related viruses: Epstein-Barr virus, human papillomavirus, human immunodeficiency virus, hepatitis B, hepatitis C, Kaposi's sarcoma-associated herpesvirus, human T-lymphotropic virus, and Merkel cell polyomavirus. In addition, to enable high resolution identification of copy number variation (CNV) calls, the entire genome was tiled with probes spaced 10kb apart. DNA and RNA were extracted from all tumors and their paired normal samples, prepared into DNA and RNA sequencing libraries and subjected to sequencing on the Illumina platform to a targeted coverage of 150X. Somatic events were identified and further filtered to identify driver events in both coding and non-coding regions. FLs demonstrated a significant degree of genetic heterogeneity with over 100 genes mutated with a frequency of at least 2%. Nearly 100% of FL cases had a mutation in at least one chromatin-modifying gene. The most frequently mutated genes in follicular lymphoma were KMT2D, BCL2, IGLL5 and CREBBP. In addition, we identified frequent mutations in SPEN, BIRC6 and SETD2. To our knowledge, this is the first description of alterations in these genes in FL. Transcriptome analysis indicated a strong correlation between BIRC6 mutations and the previously described immune response 2 signature that is associated with a poor prognosis. We further performed unbiased clustering of genetic alterations in these FL cases. We identified a cluster that was specifically enriched in BCL6 and TP53 alterations and was strongly associated with grade 3 FLs which are predicted to have poorer outcomes with low intensity therapies. We further examined the genetic profiles of 1001 DLBCLs in comparison to this cohort of FLs. Our data indicate a continuum of highly overlapping genetic alterations with DLBCL displaying more complex patterns that included alterations in MYC, TP53 and CDKN2A (mainly copy number losses), indicating shared pathogenetic mechanisms underlying FL and DLBCL, particularly those germinal center B cell origin. Disclosures Koff: Burroughs Wellcome Fund: Research Funding; V Foundation: Research Funding; Lymphoma Research Foundation: Research Funding; American Association for Cancer Research: Research Funding. Leppä:Roche: Honoraria, Research Funding; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Bayer: Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen-Cilag: Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees. Gang:ROCHE: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees. Hsi:Abbvie: Research Funding; Eli Lilly: Research Funding; Cleveland Clinic&Abbvie Biotherapeutics Inc: Patents & Royalties: US8,603,477 B2; Jazz: Consultancy. Flowers:AbbVie: Consultancy, Research Funding; Denovo Biopharma: Consultancy; BeiGene: Consultancy, Research Funding; Burroughs Wellcome Fund: Research Funding; Eastern Cooperative Oncology Group: Research Funding; National Cancer Institute: Research Funding; V Foundation: Research Funding; Optimum Rx: Consultancy; Millenium/Takeda: Research Funding; TG Therapeutics: Research Funding; Gilead: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Karyopharm: Consultancy; AstraZeneca: Consultancy; Pharmacyclics/Janssen: Consultancy, Research Funding; Spectrum: Consultancy; Bayer: Consultancy; Acerta: Research Funding; Genentech, Inc./F. Hoffmann-La Roche Ltd: Consultancy, Research Funding. Neff:Enzyvant: Consultancy; EUSA Pharma: Honoraria, Membership on an entity's Board of Directors or advisory committees. Fedoriw:Alexion Pharmaceuticals: Other: Consultant and Speaker. Reddy:Genentech: Research Funding; BMS: Consultancy, Research Funding; Celgene: Consultancy; KITE Pharma: Consultancy; Abbvie: Consultancy. Mason:Sysmex: Honoraria. Behdad:Loxo-Bayer: Membership on an entity's Board of Directors or advisory committees; Thermo Fisher: Membership on an entity's Board of Directors or advisory committees; Pfizer: Other: Speaker. Burton:Bristol-Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel; Celgene: Membership on an entity's Board of Directors or advisory committees; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees. Dave:Data Driven Bioscience: Equity Ownership.

In light of lack of efficacy associated with current cancer vaccines, we aimed to develop a novel vaccine platform called DepoVax as a therapeutic vaccine for breast/ovarian cancer. This study was designed to examine the efficacy of this novel platform over conventional emulsion vaccine using human class I MHC transgenic mice. We have developed a water-free depot vaccine formulation (DPX-0907) with high immune activating potential. Naturally processed peptides bound to HLA-A2 molecules isolated from independent breast and ovarian tumor cell lines, but not normal cells, were isolated and used as antigens in DPX-0907 along with a proprietary adjuvant and a T helper peptide epitope. Efficacy of vaccine was tested in immunized HLA-A*0201/H2Dd transgenic mice by measuring the frequency of IFN-gamma secreting cells in the draining lymph nodes, and regulatory T-cell frequencies in the spleen. Compared with a water-in-oil emulsion vaccine, DPX-0907 enhanced IFN-gamma+CD8+ T cells in vaccine site-draining lymph nodes, as seen by immunofluorescence staining and increased the frequency of IFN-gamma+ lymph node cells as seen by enzyme-linked immunosorbent spot assay. Notably, while conventional vaccine formulations elicited elevated levels of splenic Foxp3+CD4+ and IL10-secreting T cells, this was not the case for DPX-0907-based vaccines, with treated animals exhibiting normal levels of regulatory T cells. These data support the unique capabilities of a vaccine formulation containing novel tumor peptides and DPX-0907 to elicit type-1 dominated, specific immunity that may represent a potent clinical therapeutic modality for patients with breast or ovarian carcinoma.

Different molecular pathways are believed to be involved in the pathogenesis of classic Hodgkin lymphoma as opposed to non-Hodgkin lymphoma. Antiapoptotic mechanisms have been proposed for classic Hodgkin lymphoma, including expression of the cellular Fas-associated death domain-like interleukin-1beta-converting enzyme inhibitory protein (c-FLIP), which plays a critical role in resistance to CD95/Fas-mediated apoptosis. In this study, we compare the expression of c-FLIP in the neoplastic cells of classic Hodgkin lymphoma and nodular lymphocyte-predominant Hodgkin lymphoma cases. Sixteen cases of classic Hodgkin lymphoma and 19 cases of nodular lymphocyte-predominant Hodgkin lymphoma were reviewed. Of 16 classic Hodgkin lymphoma cases, 13 cases (81%) were c-FLIP-positive, compared with 6 of 19 (32%) nodular lymphocyte-predominant Hodgkin lymphoma cases. Strong cytoplasmic staining was seen in 7 of 13 c-FLIP-positive classic Hodgkin lymphoma cases, in contrast with only 2 of 6 c-FLIP-positive nodular lymphocyte-predominant Hodgkin lymphoma cases. The 2 cases of nodular lymphocyte-predominant Hodgkin lymphoma with strong c-FLIP expression were associated with transformation to large B-cell lymphoma. An additional 15 cases of diffuse large B-cell lymphoma were studied for c-FLIP expression. All but 1 were c-FLIP-positive. In conclusion, we detected c-FLIP in a significantly lower proportion of nodular lymphocyte-predominant Hodgkin lymphoma cases compared with classic Hodgkin lymphoma cases. Therefore, c-FLIP expression may not be the major mechanism of pathogenesis in nodular lymphocyte-predominant Hodgkin lymphoma. However, strong c-FLIP expression in nodular lymphocyte-predominant Hodgkin lymphoma was associated with transformation to large B-cell lymphoma in 2 cases. c-FLIP expression is not limited to Hodgkin lymphoma, because the majority of diffuse large B-cell lymphoma cases tested were strongly c-FLIP-positive.

In pursuit of physician-specific performance data in cytology, we have been calculating the ASCUS/SIL (atypical squamous cells of undetermined significance/squamous intraepithelial lesion) ratio of cytopathologists (CPs) and providing confidential feedback every 6 months. At the same time, thin-layer technology was introduced as an alternative to conventional smears. Thus we analyzed factors that may influence the ASCUS/SIL ratio, particularly the effect of periodic feedback on outliers (defined by a professional benchmark). For 3 years, the mean ASCUS/SIL ratio for all CPs decreased significantly from 2.92 to 1.87. There was great variability in the mean ASCUS/SIL ratio among 12 CPs (range, 1.11-5.89). Of the 6 CPs who worked continuously during this time, 2 showed a statistically significant decrease in their ASCUS/SIL ratio, including the CP with the highest ratio; 1 showed a significant increase. The mean ASCUS/SIL ratio did not correlate well with years of CP experience or with individual annual case volume. The ASCUS/SIL ratio of some CPs can decrease significantly over time. Whether it was due to feedback or the introduction of thin-layer preparations could not be determined.

Background: Therapeutic advances in treating Acute Myelogenous Leukemia (AML) have been limited in the past two decades. The outcome in patients over the age of 60 and those with high risk cytogenetics remains particularly poor with less than 10% of patients in this age group being cured. High dose Interleukin-2 (IL2) alone in relapsed AML has been shown to induce complete remissions. In this study we report the overall survival (OS), event free survival (EFS), responses and tolerability with IL2 therapy administered during marrow/lymphocyte recovery during induction, re-induction or consolidation. Methods: Eligibility criteria included confirmed hematopathology diagnosis of AML according to WHO classification (not including acute promyelocytic leukemia) receiving marrow suppressive treatment, a total WBC count above 500 mm3, supported platelet count above 20,000, serum creatinine ≤ 2.0 mg/dl, total bilirubin and AST < 3x upper limit of normal and hemodynamic stability. Famotidine 20 mg IV push daily was administered just prior to the IL2. IL2 therapy was infused at 18 million IU/m2 in 50ml 5% D5 or NS IVPB over 15-30 minutes daily for 5 days. Pre-medication prior to each pulse IL2 dose included acetaminophen 650 mg PO, odansetron 8mg IV, and meperidine 25 mg IV. Results: 18 pts enrolled with 12 receiving IL2 infusion. The median age was 57.5 (range 32-72). 67% women, 33% men. 8 of 12 patients had AML with myelodysplasia-related changes (including complex cytogenetics), 2 AML with inv(16), 1 AML with 11q23 translocation and 1 therapy-related AML. Median bone marrow blast percentage at diagnosis was 62% (range 32-96). 3 pts received IL2 during induction recovery, 1 during re-induction recovery, 8 during consolidation recovery. 2 pts subsequently underwent allogeneic stem cell transplantation in remission. Median follow up was 328 days (range 99-3207). Estimated 18 month overall and event free survival was 42% (CI 0.15-0.67). Of the 4 pts alive past 4 years, 3 had complex cytogenetics, 2 were greater than age 60. IL2 infusion was well tolerated without any grade 4 toxicities or hemodynamic instability requiring ventilator or hemodynamic support. Conclusion: IL-2 therapy administered during marrow/lymphocyte recovery after standard induction/consolidation chemotherapy in AML treatment achieved a 33% 4 year overall and event free survival. Disclosures No relevant conflicts of interest to declare.

Introduction: Primary central nervous system lymphoma (PCNSL) is a rare and aggressive extra-nodal lymphoma which has historically shown to be therapeutically challenging. Currently, the standard treatment remains to be high dose methotrexate (HD-MTX)-based combination chemotherapy with or without whole-brain radiotherapy. The rarity of this disease has precluded large and randomized controlled trials from taking place. In this retrospective study performed at our tertiary care academic medical center, we report our experience and characterize the nature of this disease in our patient population in a predominantly rural area of North Carolina. We demonstrate the reality and challenges of the therapeutic approaches in an attempt to achieve more durable responses and better outcomes with available treatment regimens in our patient population. Methods: After approval from our Institutional Review Board, medical records and pathology data base at our institution were reviewed to identify patients diagnosed with PCNSL between the years of 2004 and 2014. Eleven cases with no radiographic or other evidence of systemic disease who fulfilled the criteria for PCNSL according to the most recent WHO classification were included in the study. Patients' demographics, clinical presentation, radiographic and pathologic findings and treatment details and outcomes were collected and analyzed. Results: The median age at diagnosis was 60. Most patients were Caucasians (90%) with a slight predominance of males (54% males, 45% females). Clinically, most patients presented with neurologic symtpoms and deficits rather than with 'B' symptoms. Radiographically, all patients had supratentorial and multifocal involvement mostly with frontotemporal lesions. The lesions were seen crossing the corpus callosum mimicking glioblastoma multiforme in 4 patients. The pathologic features in all patients were consistent with diffuse large B-cell lymphoma (DLBCL) characterized by a diffuse intraparenchymal growth pattern. At least focal perivascular distribution of tumor cells was present in 3 cases. CD20 expression was present in all cases and 10 of 11 cases were negative for CD10, consistent with non-germinal center (non-GC) phenotype. Most tumors showed a high Ki67 proliferation rate (80-100%). Six of eleven patients had cytological assessment of the cerebrospinal fluid (CSF) at the time of diagnosis. No patients had lymphoma cells in the CSF indicating lack of leptomeningeal involvement. A total of 2 patients received induction chemotherapy based on the CALBG 50202 protocol including HD-MTX, Temozolamide and Rituxumab. Of the remaining 9 patients, 4 received HD-MTX alone, 3 received HD-MTX with concomitant intrathecal cytarabine, 1 received HD-MTX plus rituximab and 1 received Pemetrexed alone. A total of 2 patients received radiation therapy (WBRT). Five patients died of disease with time to death of disease ranging from 1.5 to 8 months. Three patients are alive at months ranging from 8 months to 3.5 years after diagnosis. One patient has been cured of their PCNSL but developed a secondary systemic DLBCL seven years later. The remaining 2 patients were lost to follow up. We were unable to determine any impact of the individual treatment modalities on the overall survival due to the small number of patients in our study. Conclusion: Our patients were predominantly Caucasian with a median age at diagnosis of 60 years. The tumors were exclusively CD20+ DLBCLs with a high Ki67 proliferation rate and a predominantly non-GC phenotype, indicating an aggressive disease pattern. Majority of the patients were unable to complete standard chemotherapy regimens previously described in the literature. Factors contributing to incomplete therapy included age more than 65 and adverse events from chemotherapy including acute kidney failure and neurotoxicity. We conclude that although HD-MTX with or without radiation therapy is the current standard treatment, it is not necessarily feasible nor appropriate in all patient populations. In our population, success was seen in patients who were younger, less than 65 years, in those who received methotrexate doses of 4g/m2 rather than the standard 8g/m2 and those who received Rituximab as part of their regimen. Larger multicenter retrospective studies may provide better insight into finding more optimal treatment regimens. Disclosures No relevant conflicts of interest to declare.

Rosai-Dorfman disease is a rare histiocytic proliferative disorder of unknown origin and a distinct clinicopathologic entity also known as sinus histiocytosis with massive lymphadenopathy. The disease can involve extranodal tissues and rarely can present as salivary gland enlargement without significant lymphadenopathy. Involvement of the extranodal head and neck sites appears to be more common in patients with immunologic abnormalities. The disease was first described in 4 patients in 1969, and with later descriptions of more patients, the disease was established as a well-defined clinicopathologic entity. The characteristic pathologic feature of this disease is proliferation of distinctive histiocytic cells that demonstrate emperipolesis in the background of a mixed inflammatory infiltrate, consisting of moderately abundant plasma cells and lymphocytes. Fine-needle aspiration biopsy can be helpful in establishing the correct diagnosis, since surgical treatment is not necessary other than obtaining tissue for definitive diagnosis. We describe cytologic, histopathologic, and immunohistochemical features of a case of Rosai-Dorfman disease that involved a major salivary gland without significant lymphadenopathy in a 48-year-old patient with systemic lupus erythematosus. We also briefly discuss possible causes and pathogenesis and review the literature.

BACKGROUND Flap necrosis remains a major complication in reconstructive surgery. The authors evaluated whether systemic activated protein C, a natural serum anticoagulant with anti-inflammatory, proangiogenic, and cytoprotective properties, can improve ischemic skin flap survival. METHODS Cranially based dorsal cutaneous flaps were elevated on 44 rats. Animals received intravenous injections of activated protein C (25 microg/kg) or saline. Rats were divided into three groups depending on the timing of the first injection: postoperative (45 minutes postoperatively, n = 12), late preoperative (45 minutes preoperatively, n = 5), and early preoperative (3 hours preoperatively, n = 5). In all groups, second and third injections were performed at 3 and 24 hours postoperatively. Flap survival was measured on day 7. Histological and real-time polymerase chain reaction specimens were collected on days 2 and 7 and at 3 and 24 hours, respectively. RESULTS Postoperative activated protein C improved flap survival (68.9 +/- 4.3 percent) compared with control treatment (39.3 +/- 1.5 percent; p < 0.001). Late preoperative treatment produced diffuse flap hemorrhage. Early preoperative activated protein C injection produced near-complete flap survival (96.1 +/- 1.1 percent for activated protein C versus 50.1 +/- 3.3 percent for control; p < 0.001). Significantly fewer inflammatory cells, improved muscle viability, and increased blood vessel density were observed in activated protein C-treated versus control rats. Activated protein C treatment significantly reduced mRNA levels of intercellular adhesion molecule-1 and tumor necrosis factor-alpha, while increasing levels of Egr-1, vascular endothelial growth factor receptor 2, and Bcl-2. CONCLUSIONS Systemic activated protein C modulates genes involved in angiogenesis, inflammation and apoptosis and improves ischemic flap survival.

BACKGROUND Bone marrow examination is essential in diagnosis, staging and monitoring of various hematologic disorders. The aspirate smears and core biopsy are complementary samples; current clinical benchmarks recommend an optimal core sample length of at least 15-20 mm. We assessed the core length in 2 cross-sectional cohorts from 2001 and 2011 in 32 academic medical centers from the US and Canada, the first such study to date. METHODS After IRB approval, participants collected data from pathology reports (including the preprocessing length) and measured aggregate postprocessing and evaluable marrow length using a uniform validated methodology on 100 consecutive marrow samples in 2001 and 2011 at each institution. Deidentified data was centralized at Roswell Park Cancer Institute (RPCI) and centers were anonymized. A total of 6374 samples were accepted for statistical analysis, performed using SAS (v. 9.4 or higher; SAS Institute, Cary, NC) at RPCI. Relationship between core length and NCCN status, geographic location, gender, age, and staging was assessed using the PROC MIXED and PROC GLIMMIX procedure using a random center effect and a nominal significance level of 0.05. RESULTS The study cohort included 56% men and 44% women, mean age 51 (range, 1-102) years, 88% adults (³18) and 12% children ( A core biopsy was obtained in 90% of 2001 and in 95% of 2011 samples. Most cores were unilateral (85%); bilateral sampling decreased from 10% to 4% between 2001 and 2011. An aspirate specimen was received in the pathology department in 86% of the cases; however, a clot section was prepared in only 56% of the cases. Preprocessing core length (PreCL; n=3141) documentation in pathology reports was missing in 9 centers for both years; in 3 centers it was available only for one year; its mean (standard deviation) was 16.9 (9.9) mm, decreasing from 2001 to 2011 [17.7 (11.9) to 16.2 (8); p=0.002]. Postprocessing core length (PostCL; n=5742) mean (SD) was 14.2 (8.5) mm, significantly shorter in women than in men (p Evaluable marrow space length (EML; n=5617) mean (SD) was 10.7 (7.5) mm and decreased from 2001 to 2011 [10.9 (8.5) to 10.6 (6.6); p=0.002]. Ninety-one samples (1.6%) with measureable PostCL were entirely devoid of evaluable marrow. PostCL was 15% shorter than PreCL. The EML measured 24% less than the PostCL and 33% less than the PreCL. Lymphoma staging samples (n=1222) were obtained from adults (96%) and children (4%); of these, only 45% and 28% reached the PostCL of 15 mm and 20 mm, respectively. Lymphoma involvement rate was 16%, 25%, 32%, 30%, and 23% when PostCL was There was no significant difference of PostCL mean based on geographic region or NCCN status. PostCL mean ranged from 8.8 to 29.6 mm and its median was ³15 mm in only 12 of 23, 9 of 32, and 2 of 32 centers for PreCL, PostCL, and EML, respectively (Fig 3). When compared to current benchmarks, only 53%, 38%, and 22% of all samples were ³15 mm and only 30%, 19%, and 10% were ³20 mm for PreCL, PostCL, and EML, respectively. CONCLUSIONS Current benchmarks for bone marrow core biopsy adequacy are met in only a minority of cases. Samples from women were shorter than from men. Bilateral sampling decreased and PreCL and EML diminished significantly between 2001 and 2011, while PostCL showed only minimal decrease. This discrepancy may be due to technical differences. Although staging cores were longer than non-staging ones, most did not meet the benchmarks. The wide variability among different centers suggests significant institutional differences and lack of standardization in bone marrow sampling. Over a third of all centers did not record preprocessing length, an important parameter which may guide operator assessment of adequacy at the bedside. PostCL and/or EML can be measured by the pathologist and integrated in the report to document adequacy. In staging samples, a minimal marrow space sampling should be required to avoid understaging. Consensus definition of an inadequate core biopsy is currently lacking but would be desirable for uniform pathology reporting, clinical protocols and management. Figure 1 Figure 1. Figure 2 Figure 2. Figure 3 Figure 3. Disclosures No relevant conflicts of interest to declare.

Erdheim-Chester disease (ECD) is a rare xanthomatous non-Langerhans cell histiocytosis which involves the marrow space of the long bones. Extraosseous sites most commonly affected include the eyes, lungs, pituitary glands, and kidneys. We report the case of a 49-year-old woman who presented with palpable breast nodules, followed by progressive soft tissue and subcutaneous disease, and involvement of the long bones, dysarthria, and dysphagia. The histopathologic features and skeletal radiography findings are consistent with ECD. This case represents an unusual presentation, which led to delayed diagnosis, as ECD of the breast has been rarely reported. ECD should be considered in the differential diagnosis of histiocytoid breast lesions, including fat necrosis and histiocytoid invasive mammary carcinoma.

Background Anterior mediastinal masses are a rare but well documented finding in Graves disease. The vast majority of these lesions represents benign thymic hypertrophy and regress after treatment of the hyperthyroidism. A small percentage of these cases however represent neoplastic/malignant diseases which require further treatment. Cases 12 year old boy with one year history of refractory Graves disease was found to have an anterior mediastinal mass and underwent curative thyroidectomy for sustained hyperthyroidism. Cervical lymphadenopathy was detected during the procedure and biopsy was obtained. A 23 year old woman who presented with a one month history of hyperthyroid symptoms, was diagnosed with Graves disease and also was found to have an anterior mediastinal mass on imaging. Biopsy of the anterior mediastinal mass was obtained and subsequently the patient underwent robotic thymectomy. Histologic examination and immunophenotyping of the cervical lymph node in a 12 year old boy revealed neoplastic proliferation of T lymphoblasts diagnostic of T lymphoblastic leukemia/lymphoma. Examination of the anterior mediastinal mass biopsy in the 23 year old woman revealed type B1 thymoma which was confirmed after examination of the subsequent robotic thymectomy specimen. Conclusion This is the first reported case of T cell lymphoblastic lymphoma and the third reported case of thymoma associated with sustained hyperthyroidism due to Graves disease. These cases indicate that an anterior mediastinal mass in a patient with active Graves disease may be due to a neoplastic cause, which may require definitive treatment. Caution should be exercised when dismissing a mediastinal mass as benign thymic hyperplasia in patients with active Graves disease.

Abstract 4471 Chronic myeloid leukemia (CML) is associated with the reciprocal t(9;22)(q34;q11) translocation, which generates the BCR-ABL fusion oncogene and is the most common myeloproliferative disease affecting adults. The clinical outcome in this disease has been revolutionized with the use of imatinib mesylate (Gleevec), a targeted tyrosine kinase inhibitor, and molecular surveillance, with the development of quantitative PCR (qPCR) approaches to measure BCR-ABL transcript levels. A number of guidelines outlining follow-up strategies for patients with chronic phase CML on imatinib therapy have been established. Once a patient is stable, a typical recommendation includes peripheral blood (PB) monitoring by qPCR of BCR-ABL levels every 3–6 months to determine response or relapse, with consideration of annual bone marrow (BM) examinations to assess for cytogenetic evolution. At the Queen Elizabeth II Health Sciences Centre and IWK Health Centre in Halifax, Nova Scotia, 34 patients with chronic phase CML on imatinib were identified from 2006 to 2008, with 36 paired samples, where transcript levels were assessed in both PB and BM within one week of each other. In 24 of the cases, the BCR-ABL transcript levels in PB and BM were within 0.5 log values of each other. In the remaining 12 cases, BCR-ABL transcript levels differed by greater than 0.5 log. Three cases had higher BM levels, but surprisingly, 9 patients had a higher BCR-ABL transcript level in the PB. In all cases, BCR-ABL levels were assessed by Q-RT-PCR using the ABI7500 instrument and primers and probe designed to detect p210 and p190 breakpoints. Results were recorded as a ratio of %BCR-ABL to GAPDH that was amplified as an internal control. There was no significant difference in clinical, morphological or laboratory parameters between these patients and others who had comparable PB and BM BCR-ABL levels. These findings highlight the need to compare BCR-ABL transcript levels derived from the same tissue during longitudinal monitoring. Moreover, while potentially due to stochastic factors, the striking observation of higher PB BCR-ABL transcript levels raises the question of which tissue represents the most accurate source for monitoring of BCR-ABL transcript levels and whether there is value in confirming a significant change in PB transcript level with BM evaluation. The discrepant levels in PB and BM could not be attributed to technical issues; the timing of sample processing from collection and quality of mRNA were comparable and no variability was observed in GAPDH levels to account for the difference. Without a technical explanation, the mechanism underlying this phenomenon remains uncertain. We speculate that it may reflect CML stem cell geography with one possibility being that the CML niche may be located external to the BM. Further studies are needed to confirm these observations. If corroborated, then revision of surveillance approaches for chronic phase patients may be indicated. Disclosures: No relevant conflicts of interest to declare.

Lymphomas are a diverse group of solid tumors of lymphoid cells that are broadly subdivided into Hodgkin lymphoma (HL) and non-Hodgkin lymphoma (NHL) categories. In the Western world, lymphoma is the most common hematologic malignancy. Complete and accurate staging of the patient with lymphoma is essential in determining the extent of initial disease. Bone marrow biopsy (BMB) remains the gold standard for assessing bone marrow involvement by lymphoma. It allows morphological diagnosis as well as the use of immunohistochemistry in difficult cases. At the time of BMB, other specimens are often gathered for use in ancillary investigations that can aid in diagnosis and/or staging. These investigations include bone marrow aspirate (BMA), flow cytometry (FC), and molecular studies (M) such as PCR. The objectives of this study were to evaluate the performance characteristics of BMA, FC, and M relative to BMB in lymphoma staging, to determine how frequently ancillary testing is positive for bone marrow involvement with lymphoma while BMB is negative, as well as to determine the clinical significance of this situation. Retrospective analysis was performed on 294 lymphoma cases from 1997 to 2002 at a single adult tertiary care center. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), pre-test probability (PreTP), post-test probability given a positive test result (PTP+), and post-test probability given a negative test result (PTP−) were determined. Chart review was performed to determine clinical significance of the situation when BMB is negative and one or more ancillary investigations are positive. The number of cases positive for lymphoma by BMB, BMA, M, and FC was 157,113, 109, and 111, respectively. The performance characteristics are indicated in Table I. Twelve cases in which one or more ancillary investigations were positive when BMB was negative were identified. Clinical management was not altered in these cases. In staging of lymphoma, BMB remains the gold standard for the determination of bone marrow involvement. When compared to BMB, ancillary investigations have a high specificity and PPV, but only moderate sensitivity and NPV. Ancillary bone marrow investigations appear to add little information to lymphoma staging, and may not be fiscally justified. Table I. Performance Characteristics Of Ancillary Bone Marrow Investigations In The Staging Of Lymphoma Parameter Bone Marrow Aspirate Molecular FlowCytometry Abbreviations: PPV = positive predictive value; NPV = negative predictive; PreTP = pre-test probability; PTP+ = post-test probability given a positive test result; PTP− = post-test probability given a negative test result Sensitivity 71% 64% 68% Specificity 98% 93% 96% PPV 97% 92% 95% PreTP 53% 53% 53% PTP+ 97% 92% 95% PTP− 26% 31% 28%

Persistent polyclonal B-cell lymphocytosis (PPBL) is rare and intriguing hematological disorder predominantly reported in young to middle- aged smoking women. It is characterized by persistent moderate polyclonal B-cell lymphocytosis with circulating hallmark binucleated lymphocytes and elevated polyclonal serum IgM. Most patients have benign clinical course on long-term follow-up. Some pathologic features of PPBL may resemble malignant lymphoma, including morphology as well as frequent cytogenetic and molecular abnormalities. Significant symptomatic splenomegaly requiring splenectomy is very unusual for this disorder; therefore there is a lack of descriptions of the morphologic features of the spleen in the literature. We present here one of the first detailed descriptions of the morphologic and immunohistochemical features of the spleen from a young female with PPBL who developed massive splenomegaly during 6-year follow up. Splenectomy was performed for symptomatic relief and suspicion of malignant process. The morphological and immunohistochemical features of the spleen closely mimicked involvement by B-cell lymphoma, however there was no monotypic surface light chain restriction seen by flow cytometry and no clonal rearrangement of IgH gene was detected by molecular analysis. Evaluating a splenectomy sample in cases like this may present a diagnostic challenge to pathologists. Therefore, correlation with B cell clonality studies (by flow cytometry and molecular analysis), clinical findings and peripheral blood morphology searching for characteristic binucleated lymphocytes is essential to avoid misdiagnosing this benign process as B-cell lymphoma. We also present here a literature review on pathogenesis of PPBL. Virtual slides The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/5329558967545656