p53 immunohistochemistry as an ancillary tool for rapid assessment of residual disease in TP53-mutated acute myeloid leukemia and myelodysplastic syndromes.

OBJECTIVES: Measurable residual disease flow cytometry (MRD-FC) and molecular studies are the most sensitive methods for detecting residual malignant populations after therapy for TP53-mutated acute myeloid leukemia and myelodysplastic neoplasms (TP53+ AML/MDS). However, their sensitivity is limited in suboptimal aspirates or when the immunophenotype of the neoplastic blasts overlaps with erythroids or normal maturing myeloid cells. In this study, we set out to determine if p53 immunohistochemistry (IHC) correlates with MRD-FC and next-generation sequencing (NGS) in the posttherapy setting and to determine the utility of p53 IHC to detect residual disease in the setting of negative or equivocal MRD-FC. METHODS: We retrospectively identified 28 pre- and posttherapy bone marrow biopsy specimens from 9 patients with TP53+ AML/MDS and a p53 overexpressor phenotype by IHC (strong 3+ staining at initial diagnosis). Next-generation sequencing and/or MRD-FC results were collected for each specimen. RESULTS: Using a threshold of more than ten 2-3+ cells in any one 400× field, p53 IHC detected residual disease with a sensitivity of 94% and a specificity of 89%. The threshold used in this study showed a high degree of concordance among 6 blinded pathologists (Fleiss κ = 0.97). CONCLUSIONS: Our study suggests that p53 IHC can be used as a rapid tool (within 24 hours) to aid in the detection of residual disease that may complement MRD-FC or NGS in cases in which the flow cytometry immunophenotype is equivocal and/or the bone marrow aspirate is suboptimal.

Diagnostic Discrepancies in Small-volume Biopsy for the Initial Diagnosis, Recurrence, and Transformation of Follicular Lymphoma: A Multi-Institutional Collaborative Study.

Small-volume biopsies (SVBs) including fine-needle aspiration (FNA), cell block, and needle core biopsies (NCB) are increasingly utilized to diagnose and guide the clinical management of lymphoma. We established a multi-institutional interdisciplinary collaboration of cytopathologists, hematopathologists, and oncologists focused on the role of SVB in the management of patients with follicular lymphoma (FL). To assess the performance characteristics of SVB in this setting, we evaluated all consecutive SVBs performed for clinical indications of initial diagnosis, recurrence, or transformation of FL over a 5-year period and focused on the 182 that had at least one subsequent biopsy within 3 months as part of the same clinical work-up. The most common outcome of a subsequent biopsy as part of the same clinical work-up was a more specific diagnosis usually assigning the pathologic grade (111/182, 61%), followed by a complete agreement with the SVB (24/182, 13%), and change from nondiagnostic on initial biopsy to diagnostic on subsequent biopsy (21/182, 12%). A minority resulted in a diagnostic change from benign to lymphoma (17/182, 9%), a change in FL grade (5/182, 3%), or change in the lymphoma diagnostic category (4/182, 2%). There were no cases where an initial diagnosis of lymphoma was overturned. The distribution of discrepancies was similar across initial SVB types (FNA, FNA + cell block, NCB with or without FNA). Tissue limitations were noted in a minority of cases (53/182, 29%) and were enriched among initially nondiagnostic biopsies (16/21, 76%). Flow cytometry immunophenotyping was performed in the majority of cases both at the first and last biopsy (147/182, 81%). SVB can be a powerful method to detect FL in various clinical indications, with discrepant cases mostly resulting from a refinement in the initial diagnosis.

Small volume biopsy diagnostic yield at initial diagnosis versus recurrence/transformation of follicular lymphoma: A retrospective Cyto-Heme Interinstitutional Collaborative study.

BACKGROUND: Few studies have evaluated diagnostic yield of small volume biopsies (SVB) for the diagnosis and management of follicular lymphoma (FL). METHODS: The authors performed a multi-institutional retrospective analysis of SVBs including fine-needle aspiration (FNA) and needle core biopsy (NCB) for initial FL diagnosis and suspected recurrence or transformation of FL. A total of 676 workups beginning with SVB were assessed for the mean number of biopsies per workup, the proportion of workups requiring multiple biopsies, and the proportion with a complete diagnosis including grade, on initial biopsy. RESULTS: Compared to workups performed for question transformation/recurrence, those done for initial FL diagnosis were significantly more likely to require multiple biopsies (p < .01), had a higher mean number of biopsies per workup (1.7 vs. 1.1, absolute standardized difference = 1.1), and a lower complete diagnosis rate at initial biopsy (39% vs. 56%). At initial FL diagnosis, NCB +/- FNA was associated with fewer biopsies per workup compared to FNA +/- CB (1.2 vs. 1.9), fewer workups requiring multiple biopsies (23% vs. 83%), and a higher complete diagnosis rate (71% vs. 18%). In contrast, during assessment for transformation/recurrence, NCB and FNA showed a similar mean number of biopsies per workup (1.2 vs. 1.2) and few workups required multiple biopsies (6% vs. 19%). CONCLUSIONS: SVB at initial FL diagnosis often required additional biopsies to establish a complete diagnosis. In contrast, when assessing for transformed/recurrent FL, additional biopsies were generally not obtained regardless of SVB type, suggesting that in these clinical settings SVB may be sufficient for clinical decision-making.

Cytomorphologic features of pediatric-type follicular lymphoma on fine needle aspiration biopsy: case series and a review of the literature.

INTRODUCTION: Pediatric-type follicular lymphoma (PTFL) is a rare and recently recognized subtype of nodal follicular B-cell lymphoma. While significant recent progress has been made in understanding the morphologic, immunophenotypic, and molecular findings, there are only rare case reports describing the cytomorphologic features of PTFL. MATERIALS AND METHODS: Four cases of PTFL initially evaluated on fine needle aspiration (FNA) biopsy were retrieved from our institutions' databases. The cytologic and subsequent surgical excision specimens were compared in terms of cytology, histology, immunophenotype, and molecular findings. RESULTS: A constellation of cytologic features for PTFL are able to distinguish it from other cytomorphologic entities in the differential including: 1) the presence of large blastoid cells with fine chromatin and irregular nuclear membranes, 2) small/intermediate-sized lymphocytes with subtle nuclear membrane irregularities, 3) near complete absence of cytoplasmic vacuoles in lymphoid cells, 4) tingible body macrophages, 5) mitotic figures, 6) absence of a diffuse large cell component, 7) and no significant plasma cell population. CONCLUSIONS: We present four cases of PTFL initially evaluated on FNA biopsy and define the cytomorphologic features of PTFL. FNA biopsy is presented as a practical tool for initial evaluation of this rare entity as part of a multimodal diagnostic approach, for which increased awareness among cytopathologists can ensure the appropriate triage of specimen studies necessary for the diagnosis. Additionally, we comprehensively review the current literature on PTFL and discuss the differential diagnosis on cytology, including potential pitfalls.

Global Cytopathology-Hematopathology Practice Trends.

OBJECTIVES: Small-volume biopsy-fine-needle aspiration biopsy (FNAB) with or without core biopsy-is in increasing use in diagnosis and management of lymphoma patients. Our objective was to survey the current practice in small-volume biopsy diagnosis of lymphoma, focusing on the interaction among hematopathologists and cytopathologists and the integration of FNAB, core biopsy, and flow cytometry studies at sign-out. METHODS: This study used a cross-sectional survey design employing the RedCap database distributed via nine pathology professional society email listservs. The survey consisted of 25 multiple-choice questions and several free text fields. In total, 128 pathologists participated. RESULTS: Most respondents indicated that FNAB specimens in which lymphoma is a diagnostic consideration (FNAB-L) are seen daily or weekly (68/116; 58.6%). However, most institutions have separate hematopathology and cytopathology services (72/116; 62.1%) with inconsistent communication. When communication occurred, respondents were frequently inclined to reconsider their original diagnoses. Barriers identified included lack of communication, inadequate access to diagnostic studies, no formal subspecialty training, and various opinions regarding FNAB in diagnosing lymphoma. CONCLUSIONS: This survey showed that FNAB-L specimens are common, with a lack of uniformity in how complementary fine-needle aspiration and core biopsy specimens or flow immunophenotyping results are shared across hematopathology and cytopathology services.

Cancers associated with human gammaherpesviruses.

Epstein-Barr virus (EBV; human herpesvirus 4; HHV-4) and Kaposi sarcoma-associated herpesvirus (KSHV; human herpesvirus 8; HHV-8) are human gammaherpesviruses that have oncogenic properties. EBV is a lymphocryptovirus, whereas HHV-8/KSHV is a rhadinovirus. As lymphotropic viruses, EBV and KSHV are associated with several lymphoproliferative diseases or plasmacytic/plasmablastic neoplasms. Interestingly, these viruses can also infect epithelial cells causing carcinomas and, in the case of KSHV, endothelial cells, causing sarcoma. EBV is associated with Burkitt lymphoma, classic Hodgkin lymphoma, nasopharyngeal carcinoma, plasmablastic lymphoma, lymphomatoid granulomatosis, leiomyosarcoma, and subsets of diffuse large B-cell lymphoma, post-transplant lymphoproliferative disorder, and gastric carcinoma. KSHV is implicated in Kaposi sarcoma, primary effusion lymphoma, multicentric Castleman disease, and KSHV-positive diffuse large B-cell lymphoma. Pathogenesis by these two herpesviruses is intrinsically linked to viral proteins expressed during the lytic and latent lifecycles. This comprehensive review intends to provide an overview of the EBV and KSHV viral cycles, viral proteins that contribute to oncogenesis, and the current understanding of the pathogenesis and clinicopathology of their related neoplastic entities.

Pitfalls in the Diagnosis of Nodular Lymphocyte Predominant Hodgkin Lymphoma: Variant Patterns, Borderlines and Mimics.

Nodular lymphocyte predominant Hodgkin lymphoma (NLPHL) represents approximately 5% of Hodgkin lymphoma and typically affects children and young adults. Although the overall prognosis is favorable, variant growth patterns in NLPHL correlate with disease recurrence and progression to T-cell/histiocyte-rich large B-cell lymphoma or frank diffuse large B-cell lymphoma (DLBCL). The diagnostic boundary between NLPHL and DLBCL can be difficult to discern, especially in the presence of variant histologies. Both diagnoses are established using morphology and immunophenotype and share similarities, including the infrequent large tumor B-cells and the lymphocyte and histiocyte-rich microenvironment. NLPHL also shows overlap with other lymphomas, particularly, classic Hodgkin lymphoma and T-cell lymphomas. Similarly, there is overlap with non-neoplastic conditions, such as the progressive transformation of germinal centers. Given the significant clinical differences among these entities, it is imperative that NLPHL and its variants are carefully separated from other lymphomas and their mimics. In this article, the characteristic features of NLPHL and its diagnostic boundaries and pitfalls are discussed. The current understanding of genetic features and immune microenvironment will be addressed, such that a framework to better understand biological behavior and customize patient care is provided.

Impact of initial biopsy type on the time to final diagnostic biopsy in patients with follicular lymphoma and suspected histologic transformation.

Diagnosis of histologic transformation (HT) of follicular lymphoma (FL) requires tissue biopsy. While surgical biopsy represents the gold standard, less invasive procedures such as fine-needle aspiration biopsy (FNAB) and core needle biopsy (CNB) are frequently performed. In this retrospective multi-institutional study including 269 patients with FL and suspected HT, the median time from initial clinical suspicion to final diagnostic biopsy was similar whether the workup began with FNAB, CNB, or surgical biopsy (4, 9, and 6 days, respectively; p=.27), despite more subsequent biopsies performed following initial FNAB. Periprocedural complications were uniformly minimal. Biopsy-proven HT was more common in the initial surgery group and in workups including positron emission tomography/computed tomography (PET/CT). Our findings, derived from US academic centers with specialized procedural and pathology expertise, suggest that FNAB, CNB, and surgical biopsy are all viable initial diagnostic procedures that can inform clinical decision-making in select FL patients with suspected HT.

CD20-Negative Nodular Lymphocyte-Predominant Hodgkin Lymphoma: A 20-Year Consecutive Case Series From a Tertiary Cancer Center.

CONTEXT.­: Nodular lymphocyte-predominant Hodgkin lymphoma (NLPHL) is a rare, indolent Hodgkin lymphoma subtype with distinct clinicopathologic features and treatment paradigms. The neoplastic lymphocyte-predominant cells typically express bright CD20 and other B-cell antigens, which distinguishes them from Hodgkin/Reed-Sternberg cells of lymphocyte-rich classic Hodgkin lymphoma. OBJECTIVE.­: To characterize the clinicopathologic features of CD20-negative NLPHL at a single institution. DESIGN.­: A retrospective search for CD20-negative NLPHL in our pathology archives and medical records was conducted. RESULTS.­: Of 486 NLPHL patients identified with CD20 available for review, 14 (2.8%) had LP cells with absent CD20 expression. Patients with prior rituximab administration (n = 7) and insufficient clinical history (n = 1) were excluded, leaving 6 patients with rituximab-naïve, CD20-negative NLPHL. A broad immunohistochemical panel showed the LP cells in all cases expressed B-cell antigens, particularly Oct-2, although PAX5 and CD79a were frequently also dim. CD30, CD15, and Epstein-Barr virus-encoded small RNAs were negative in all evaluated cases. Two patients had high-risk variant immunoarchitectural pattern D. One patient had extranodal disease, involving the spleen and bone, and was suspected to have large cell transformation. Standard NLPHL therapy was given, including local radiation and/or chemotherapy. Of 5 patients with available follow-up, 4 are alive in complete remission after therapy, and 1 is alive with relapsed disease. CONCLUSIONS.­: NLPHL can lack CD20 de novo without prior rituximab therapy. In such cases, extensive immunophenotyping helps distinguish NLPHL from lymphocyte-rich classic Hodgkin lymphoma, which differ in clinical behavior and therapy. In our series, CD20-negative NLPHL showed both classic and variant histologic patterns and the expected range of clinical behavior seen in NLPHL, including 1 case with suspected large cell transformation.

Complexities in the diagnosis of large B-cell lymphomas, classic Hodgkin lymphomas and overlapping peripheral T-cell lymphomas simplified: An evidence-based guide.

The diagnosis of a large B-cell lymphoma and classic Hodgkin lymphoma (CHL) is often straightforward. However, in select circumstances, these simple diagnoses can be quite complex. In part, diagnostic difficulty may be due to uncertainty in the evaluation of morphologic and immunophenotypic features along a biologic continuum, or alternatively arise from uncertainty in predicting the behavior and outcomes of patients. Here, we systematically discuss and review areas of diagnostic difficulty in the diagnosis of large B-cell lymphomas (LBCL), classic Hodgkin lymphomas (CHL) and peripheral T-cell lymphomas (PTCL). We provide careful data-driven analyses and evidence-based approaches to help guide pathologists and clinicians. We discuss: 1) marginal zone lymphomas with increased large cells versus diffuse large B-cell lymphoma (DLBCL), 2) chronic lymphocytic leukemia with expanded proliferation centers versus diffuse large B-cell lymphoma (DLBCL), 3) chronic lymphocytic leukemia with Hodgkin/Reed-Sternberg-like cells versus CHL arising from chronic lymphocytic leukemia, 4) complex cases of follicular lymphoma versus DLBCL, 5) PTCL with large B-cell proliferations versus PTCL with LBCL, 6) PTCL with Hodgkin/Reed-Sternberg-like cells versus CHL, and finally 7) blastoid/pleomorphic mantle cell lymphoma versus DLBCL. Our evidence and data driven approach may serve as a useful diagnostic guide.

Histiocytic Sarcoma Associated With Follicular Lymphoma: Evidence for Dramatic Response With Rituximab and Bendamustine Alone and a Review of the Literature.

Histiocytic sarcoma (HS) is a rare aggressive malignancy with a dismal prognosis and no agreed-upon standard treatment. Classically, the diagnosis of HS has been difficult to confirm and has relied on inaccurate, crude techniques. Therapy often involves intensive chemotherapeutic regimens, surgery, and/or radiotherapy, which are poorly tolerated with variable response rates. Patients often die of diffusely metastatic disease. Modern diagnostic techniques are helping to slowly uncover more uniquely customized therapeutic approaches in this enigmatic disease. We present a review of the current literature regarding HS diagnosis, treatment, and outcomes. Additionally, we describe the first reported case of HS transdifferentiated from follicular lymphoma that had a dramatic and durable response to rituximab/bendamustine alone as initial treatment. Unlike traditional chemotherapy regimens, this treatment was well tolerated and had a good toxicity profile. The combination of rituximab and bendamustine warrants further investigation in the treatment of HS, especially those originating from prior follicular lymphoma. Modern immunohistochemical and molecular profiling techniques are beginning to reveal heterogeneity among HS tumors and potentially therapeutic targets.

Prostate-Specific Membrane Antigen-Targeted Imaging With [18F]DCFPyL in High-Grade Gliomas.

High-grade gliomas (World Health Organization grade III-IV) are highly lethal primary brain tumors. Imaging modalities, including MRI and FDG PET, provide a limited ability to differentiate treatment effects (such as radiation necrosis) from recurrent or residual tumor. As the first step in validating the applicability of prostate-specific membrane antigen (PSMA)-targeted imaging in high-grade gliomas, we evaluated the ability of the PSMA-targeted small molecule [F]DCFPyL (2-(3-(1carboxy-5-(6-[F]fluoro-pyridine-3-carbonyl)-amino]-pentyl)-ureido)-pentanedioic acid) to image high-grade gliomas in a series of 3 prospectively recruited patients. We found [F]DCFPyL binds PSMA in the neovasculature of glioblastoma multiforme and tumor cells of anaplastic astrocytoma.

Mantle cell lymphoma with a novel t(11;12)(q13;p11.2): a proposed alternative mechanism of CCND1 up-regulation.

Mantle cell lymphoma (MCL) is typically characterized by t(11;14), which places the IGH@ enhancer elements upstream of CCND1. This fusion results in up-regulation of CCND1 and consequently its protein product cyclin D1. Recent studies have shown that in MCL, mutations or translocations occurring within the 3' untranslated region (UTR) of the CCND1 gene can result in a truncated mRNA transcript that is more stable and associated with more aggressive disease. We identified a case of MCL showing cyclin D1 overexpression by immunohistochemistry and a t(11;12)(q13;p11.2) by conventional cytogenetic studies. Next-generation genomic sequencing indicated a chromosomal break through the CCND1 3'-UTR and fusion with a non-coding region of chromosome 12. We suggest that, in the absence of the typical CCND1/IGH@ fusion, this rearrangement promotes MCL pathogenesis by eliminating miRNA interaction elements within the 3'-UTR of the CCND1 mRNA transcript consequently resulting in CCND1 overexpression.

Improving supervised learning by adapting the problem to the learner.

While no supervised learning algorithm can do well over all functions, we show that it may be possible to adapt a given function to a given supervised learning algorithm so as to allow the learning algorithm to better classify the original function. Although this seems counterintuitive, adapting the problem to the learner may result in an equivalent function that is "easier" for the algorithm to learn. One method of adapting a problem to the learner is to relabel the targets given in the training data. The following presents two problem adaptation methods, SOL-CTR-E and SOL-CTR-P, variants of Self-Oracle Learning with Confidence-based Target Relabeling (SOL-CTR) as a proof of concept for problem adaptation. The SOL-CTR methods produce "easier" target functions for training artificial neural networks (ANNs). Applying SOL-CTR over 41 data sets consistently results in a statistically significant (p < 0.05) improvement in accuracy over 0/1 targets on data sets containing over 10,000 training examples.