Shades of gray between large B-cell lymphomas and Hodgkin lymphomas: differential diagnosis and biological implications

Variant histology of pediatric nodular lymphocyte-predominant Hodgkin lymphoma with IgD and CD30 expression

BACKGROUND

Nodular lymphocyte-predominant Hodgkin lymphoma (NLPHL), recently known as nodular lymphocyte-predominant B-cell lymphoma (NLPBL), accounts for 5%-10% of Hodgkin lymphoma (HL). Different morphologic patterns of NLPBL are identified and categorized as typical patterns (type A and B) and variant histologic patterns (types C, D, E, and F).

PATIENTS AND METHOD

We investigated different morphologic patterns, CD30 and IgD expression in pediatric patients with NLPBL diagnosed at the Children's Cancer Hospital Egypt.

RESULTS

Forty-six (53%) of the patients exhibited a typical histologic pattern, whereas the remaining (47%) exhibited variant histologic pattern. Variant histology is associated with unfavorable clinical characteristics, such as advanced stages, B-symptoms, and extranodal involvements, particularly bone marrow and bone infiltration, with p-values of .06, .05, and 0.01%, respectively. Additionally, 39% of patients with variant histology experienced disease progression or relapse, compared to only 15.2% of patients with typical patterns (p = .009). Types C and D are related to decreased event-free survival (EFS), as shown by a p-value of .05. The 5-year EFS for patients with variant histology was 94.4% for the rituximab, cyclophosphamide, vincristine, doxorubicin, and prednisone (RCHOP) versus 33.3% for the adriamycin, bleomycin, vinblastine, and dacarbazine (ABVD). IgD expression in lymphocyte-predominant (LP) cells was detected in 44 (50%) patients, while CD30 expression in LP cells was found in 39 (44%) patients.

CONCLUSION

Variant histology of NLPBL was associated with advanced disease stages and a poor prognosis, while expression of IgD and CD30 in LP cells was not. The poor outcome of variant histology improved with the RCHOP regimen.

Hodgkin Lymphoma and Its Differential Diagnosis: New Twists on an Old Challenge

Hodgkin lymphoma is a B-cell neoplasm that typically presents with localized, nodal disease. Tissues are characterized by few large neoplastic cells, usually comprising less than 10% of tissue cellularity, present in a background of abundant nonneoplastic inflammatory cells. This inflammatory microenvironment, although key to the pathogenesis, can make diagnosis a challenge because reactive conditions, lymphoproliferative diseases, and other lymphoid neoplasms may mimic Hodgkin lymphoma and vice versa. This review provides an overview of the classification of Hodgkin lymphoma, its differential diagnosis, including emerging and recently recognized entities, and strategies to resolve challenging dilemmas and avoid diagnostic pitfalls.

Simultaneous nodular lymphocyte-predominant Hodgkin lymphoma with papillary thyroid carcinoma: a case report

We herein report the case of a 48-year-old man diagnosed with nodular lymphocyte-predominant Hodgkin lymphoma (NLPHL, Stage IA) and papillary thyroid carcinoma (PTC, Stage I). Total thyroidectomy, left modified neck dissection and biopsy of the right cervical lymph node were performed. Postoperatively, NLPHL treatment was prioritized, and external radiation (30.6 Gy) was applied to the right neck. PTC was considered a high-risk category for recurrence due to extranodal invasion of lymph node metastasis, and radioactive iodine therapy (ablative dose, 1110 MBq) was administered. Both PTC and NLPHL showed no recurrence 18 months after surgery.

The utility of IMP3 immunohistochemical staining in differentiating nodular lymphocyte predominant Hodgkin Lymphoma from T-Cell/Histiocyte-Rich large B-Cell lymphoma

INTRODUCTION

Nodular lymphocyte predominant Hodgkin lymphoma (NLPHL) and T cell/histiocyte-rich large B-cell lymphoma (THRLBCL) have overlapping histological features that make their diagnosis challenging. Insulin-like growth factor II mRNA-binding protein 3 (IMP3) is a recently proposed diagnostic marker for Hodgkin's lymphoma. The aim of this study was to determine the ability of IMP3 in differentiating NLPHL from THRLBCL.

METHODS

In this retrospective study, the formalin-fixed paraffin-embedded blocks from 56 patients (28 NLPHL and 28 large B cell lymphoma (LBCL, including 16 THRLBCL and 12 DLBCL, NOS) cases based on immunohistochemistry (IHC) were included. Sample sections were stained for IMP3 using IHC method. Moderate to strong staining in at least 10% of tumor cells was considered positive IMP3 expression.

RESULTS

The mean age of the patients was 41.25 ± 16.08 years old. The majority of the patients were male. There was a significant age difference between NLPHL (34.61 ± 16.44 years old) and LBCL (47.89 ± 12.85 years) groups (p = 0.001). No significant difference was seen in gender and site between NLPHL and LBCL groups. The expression of IMP3 was mainly strong in LBCL group, while it was heterogeneously distributed among NLPHL samples ranging from weak to strong (p < 0.001). It was determined that strong IMP3 expression at 55.00% can differentiate LBCL from NLPHL with 71.4% sensitivity and 71.4% specificity.

CONCLUSION

Our findings showed that IMP3 may be a good complement in differentiating NLPHL cases from THRLBCL.

T, Manikandan A, Ravichandar S. Petals of rose: Application of rapid on-site evaluation in bronchoscopy

In present day scenario, procedures that are minimally invasive like FNAs and Core needle biopsies are on the rise. Rapid on-site evaluation (ROSE) is a laboratory service that assesses the cytomorphologic features from FNA smears or biopsy contact imprints in the biopsy room and can provide on the spot input and suggestions for the clinician through immediate cytological examination of the biopsy sample. ROSE also allows for a preliminary diagnosis, allowing for the requirement of additional material for ancillary studies. We are presenting two cases which highlights the merits of ROSE in cytological diagnosis.   In the first case, a thirty four year old male patient came with complaints of productive cough, breathlessness and fever. Bronchoscopic needle aspiration and biopsy was done with Rapid Onsite Evaluation. ROSE revealed two non-caseating epithelioid granulomas on the 4th pass. Bronchoscopic lymph node biopsy was non- contributory. With other clinical and biochemical parameters, diagnosis of Sarcoidosis was made. This case study underscores the significance of ROSE in arriving at the diagnosis.   In the other case, a fifty seven year old male patient came to hospital with productive cough and breathlessness (MMRC grade II). CT chest revealed features suggestive of bronchogenic carcinoma. ROSE was performed along with bronchial brush cytology in which presence of atypical cells with increased nuclear cytoplasmic ratio, nuclear hyperchromatism and nuclear molding was noted. On histopathological examination, it was diagnosed as a case of non-small cell carcinoma of lung – poorly differentiated type. This case proves the advantage of ROSE in avoiding repeated invasive procedures for the patient.

The Grey Zones of Classic Hodgkin Lymphoma

Simple Summary

Classic Hodgkin lymphoma (CHL) is a well-defined lymphoid neoplasm with a minority of characteristic neoplastic cells of B cell origin, namely Hodgkin and Reed–Sternberg cells immersed in a rich reactive inflammatory infiltrate in the background. Although CHL has always been set apart from non-Hodgkin lymphomas, cases with morphological and phenotypic features intermediate between CHL and other lymphomas have been described. Whereas some of these lymphomas only represent morphological mimics, others exhibit mutational and gene expression profiles which overlap with CHL, indicating that these cases, frequently termed grey zone lymphomas, reside on the biological boundary between CHL and large B-cell lymphomas. In the present review, we aim to describe the current knowledge of these rare lymphomas, address diagnostic issues and summarize today’s concepts on the classification of grey zone lymphomas and related tumors.

Abstract

Classic Hodgkin lymphoma (CHL) is a well-defined neoplasm characterized by the presence of a minority of pathognomonic Hodgkin and Reed–Sternberg (HRS) cells in a reactive inflammatory background. Although genotypically of B cell origin, HRS cells exhibit a downregulated B cell program and therefore are set apart from other B cell lymphomas in the current WHO classification. However, cases with morphological and phenotypic features overlapping with CHL have been recognized, and the category of B cell lymphoma—unclassifiable—with features intermediate between diffuse large B cell lymphoma (DLBCL) and CHL, also termed grey zone lymphoma, was first introduced into the WHO classification in 2008 as provisional entity. These cases, as well as others raising a differential diagnosis of CHL can present diagnostic problems, as well as therapeutic challenges. Whereas some of these lymphomas only represent biologically unrelated morphological mimics, others, especially mediastinal grey zone lymphoma, exhibit genetic and gene expression profiles which overlap with CHL, indicating a true biological relationship. In this review, we address areas of diagnostic difficulties between CHL and other lymphoma subtypes, discuss the biological basis of true grey zone lymphoma based on recent molecular studies and delineate current concepts for the classification of these rare tumors.

Primary mediastinal large B cell lymphoma with coexisting aberrations of C-MYC and BCL-2: a case report and literature review

Primary mediastinal large B-cell lymphoma (PMLBCL) is an aggressive lymphoma characteristic with distinct clinical, morphologic, and immunophenotypic features. The rearrangements of C-MYC, BCL2 and/or BCL6 which are common in diffuse large B-cell lymphoma (DLBCL) are typically absent in PLMBCL. Here we proved a novel case of PMLBCL with concurrent rearrangements of C-MYC and BCL2. Histology showed typical pathomorphological features of PLMBCL. Fluorescent in situ hybridization (FISH) studies showed rearrangements of C-MYC and copy number variation (CNV) of BCL2 gene. It is not well known on the clinical significance of rearrangements of C-MYC and BCL2 genes in PMLBCL. The case gives evidence that cytogenetic testing is necessary for PMLBCLs to get precise clinical evaluation and appropriate treatment.

Immunophenotypic Characterization and Purification of Neoplastic Cells from Lymph Nodes Involved by T-Cell/Histiocyte-rich Large B-cell Lymphoma by Flow Cytometry and Flow Cytometric Cell Sorting

BACKGROUND

T-cell/histiocyte rich large B-cell lymphoma (THRLBCL) is B-cell lymphoma in which rare neoplastic cells are embedded in a reactive infiltrate. We describe the first characterization of the neoplastic cells by flow cytometry (FC).

METHODS

Using FC, we immunophenotyped the neoplastic cells of 11 cases of THRLBCL and 11 cases of DLBCL, NOS (controls). Neoplastic THRLBCL cells were also purified by flow cytometric cell sorting (FCCS).

RESULTS

A neoplastic THRLBCL population was detected by FC in 9 of 11 cases (82%). Neoplastic THRLBCL cells demonstrated an aberrant germinal center B-cell immunophenotype (bright CD20, bright CD40; positive for Bcl-6 and CD75; weakly positive for CD32; negative for IgH). With regard to adhesion molecules, CD54 was overexpressed, CD58 expression varied between cases, and CD50 expression was intermediate. Evaluation of immunomodulatory receptors demonstrated that PD-L2 was weakly expressed and PD-L1 was variably expressed. Finally, FCCS of two cases showed large multi-lobated cells with morphology consistent with neoplastic cells of THRLBCL.

CONCLUSIONS

The immunophenotype identified and the morphology of the FCCS purified cells confirms the FC defined populations are neoplastic cells from THRLBCL. While the cohort is small, neoplastic THRLBCL cells lack surface immunoglobulins. CD40, CD50, and CD54 were overexpressed in THRLBCL relative to DLBCL, NOS, perhaps contributing to the predominance of T cells in THRLBCL. Expression of CD32, PD-L1, and PD-L2 may be useful in distinguishing THRLBCL and NLPHL. Finally, the FC assays will be useful for purifying neoplastic cells of THRLBCL and for diagnostic immunophenotyping of THRLBCL. © 2019 International Clinical Cytometry Society.

Outcomes in refractory diffuse large B-cell lymphoma: results from the international SCHOLAR-1 study

Diffuse large B-cell lymphoma (DLBCL) is the most common subtype of non-Hodgkin lymphoma. Although 5-year survival rates in the first-line setting range from 60% to 70%, up to 50% of patients become refractory to or relapse after treatment. Published analyses of large-scale outcome data from patients with refractory DLBCL are limited. SCHOLAR-1, an international, multicohort retrospective non-Hodgkin lymphoma research study, retrospectively evaluated outcomes in patients with refractory DLBCL which, for this study, was defined as progressive disease or stable disease as best response at any point during chemotherapy (>4 cycles of first-line or 2 cycles of later-line therapy) or relapsed at ≤12 months from autologous stem cell transplantation. SCHOLAR-1 pooled data from 2 phase 3 clinical trials (Lymphoma Academic Research Organization-CORAL and Canadian Cancer Trials Group LY.12) and 2 observational cohorts (MD Anderson Cancer Center and University of Iowa/Mayo Clinic Lymphoma Specialized Program of Research Excellence). Response rates and overall survival were estimated from the time of initiation of salvage therapy for refractory disease. Among 861 patients, 636 were included on the basis of refractory disease inclusion criteria. For patients with refractory DLBCL, the objective response rate was 26% (complete response rate, 7%) to the next line of therapy, and the median overall survival was 6.3 months. Twenty percent of patients were alive at 2 years. Outcomes were consistently poor across patient subgroups and study cohorts. SCHOLAR-1 is the largest patient-level pooled retrospective analysis to characterize response rates and survival for a population of patients with refractory DLBCL.

Nodular lymphocyte predominant Hodgkin's lymphoma in daily practice: A multicenter experience

Nodular lymphocyte predominant Hodgkin's lymphoma (NLPHL) is a rare subtype of Hodgkin's lymphoma. In this study, we aimed to investigate the clinical features and therapeutic outcomes of patients with NLPHL who were diagnosed at different institutes in Turkey. We retrospectively reviewed the records of the patients diagnosed with NLPHL. Adult patients who were diagnosed after 2005 with histological confirmation were selected for the study. Forty-three patients were included in the study. Median age of patients was 37.5 years (18-70) at the time of diagnosis. About 60.5% patients were diagnosed as stage I and II NLPHL, and remaining 39.5% had stage III and IV disease. Median follow-up was 46 months. During follow-up, none of the patients died. Seven patients relapsed or progressed after initial therapy at a median of 12 months. Five of 7 relapsed/refractory patients (71.4%) were salvaged with chemotherapy only (DHAP, ICE), and the remaining 2 (28.6%) were salvaged with chemoimmunotherapy. All of relapsed/refractory patients were able to achieve complete remission after salvage therapy. Lactate dehydrogenase levels were significantly higher in patients with progressive disease compared with nonprogressive disease. Our study showed an excellent outcome with all patients alive at last contact with a median follow up of 46 months despite a wide range of different therapeutic approaches. All relapsed and refractory patients were successfully salvaged despite a low frequency of patients received immunotherapy in conjunction with chemotherapy. Our results suggest that immunotherapy may be reserved for further relapses.

T cell-rich lymphoid infiltrates with large B cells: a review of key entities and diagnostic approach

Accurate diagnostic interpretation of a lymphoid population composed predominantly of small T cells, together with smaller numbers of large B cells, with or without a nodular architecture, is a common problem faced by the histopathologist. The differential diagnosis of this histological pattern is wide, ranging from reactive conditions such as drug reactions and viral infections, through borderline entities such as immunodeficiency-related lymphoproliferative disorders to lymphomas. The latter includes entities where the large B cells are primarily neoplastic (classical and nodular lymphocyte-predominant Hodgkin lymphomas and T cell/histiocyte-rich large B cell lymphoma) as well as T cell lymphomas such as angioimmunoblastic T cell lymphoma where the large B cells represent an epiphenomenon and may or may not be neoplastic. Several rare variants of these conditions, and the fact that treatment can significantly modify appearances, add to the diagnostic difficulty of these pathological entities. Unlike monomorphic lymphoid infiltrates, the histological pattern of T cell-rich proliferation with large B cells requires close evaluation of the inter-relationship between B cells and T cells, follicular dendritic cells and sometimes other inflammatory cells. Epstein-Barr virus plays a key role in several of these scenarios, and interpreting not only its presence but also its distribution within cellular subgroups is essential to accurate diagnosis and the avoidance of some important diagnostic pitfalls. An understanding of normal immunoarchitecture and lymphoid maturational pathways is also fundamental to resolving these cases, as is a knowledge of their common patterns of spread, which facilitates correlation with clinical and radiological findings.

Recent Advances in Aggressive Large B-cell Lymphomas: A Comprehensive Review

Diffuse large B-cell lymphoma (DLBCL) is an aggressive disease with considerable heterogeneity reflected in the 2008 World Health Organization classification. In recent years, genome-wide assessment of genetic and epigenetic alterations has shed light upon distinct molecular subsets linked to dysregulation of specific genes or pathways. Besides fostering our knowledge regarding the molecular complexity of DLBCL types, these studies have unraveled previously unappreciated genetic lesions, which may be exploited for prognostic and therapeutic purposes. Following the last World Health Organization classification, we have witnessed the emergence of new variants of specific DLBCL entities, such as CD30 DLBCL, human immunodeficiency virus-related and age-related variants of plasmablastic lymphoma, and EBV DLBCL arising in young patients. In this review, we will present an update on the clinical, pathologic, and molecular features of DLBCL incorporating recently gained information with respect to their pathobiology and prognosis. We will emphasize the distinctive features of newly described or emerging variants and highlight advances in our understanding of entities presenting a diagnostic challenge, such as T-cell/histiocyte-rich large B-cell lmphoma and unclassifiable large B-cell lymphomas. Furthermore, we will discuss recent advances in the genomic characterization of DLBCL, as they may relate to prognostication and tailored therapeutic intervention. The information presented in this review derives from English language publications appearing in PubMed throughout December 2015. For a complete outline of this paper, please visit: http://links.lww.com/PAP/A12.

Minimal Treatment of Low-Risk, Pediatric Lymphocyte-Predominant Hodgkin Lymphoma: A Report From the Children's Oncology Group

PURPOSE

Children's Oncology Group study AHOD03P1 was designed to determine whether excellent outcomes can be maintained for patients with low-risk, pediatric lymphocyte-predominant Hodgkin lymphoma (LPHL) with a strategy of resection alone or minimal chemotherapy.

PATIENTS AND METHODS

Patients with stage IA LPHL in a single node that was completely resected were observed without further therapy; recurrences were treated with three cycles of doxorubicin/vincristine/prednisone/cyclophosphamide (AV-PC). Patients with unresected stage IA or stage IIA LPHL were treated with three cycles of AV-PC. Patients with less than a complete response (CR) to AV-PC received 21-Gy involved-field radiation therapy (IFRT).

RESULTS

A total of 183 eligible patients were enrolled; 178 were evaluable. Of these, 52 patients underwent complete resection of a single node. There were 13 relapses at a median of 11.5 months; 5-year event-free survival (EFS) was 77% (range, 62% to 87%). A total of 135 patients received AV-PC; 126 were treated at diagnosis and nine at relapse after surgery alone. Eleven patients receiving AV-PC had less than CR and received IFRT. Fourteen first events occurred among 135 patients (12 relapses and two second malignancies). Two relapses occurred in patients who had received IFRT. Five-year EFS was 88.8% (95% CI, 81.8% to 93.2%). Five-year EFS for the entire cohort was 85.5% (95% CI, 79.2% to 90.1%); overall survival was 100%.

CONCLUSION

Some 75% of highly selected pediatric patients with LPHL may be spared chemotherapy after surgical resection alone. Pediatric LPHL has excellent EFS with chemotherapy that is less intensive than standard regimens; > 90% of patients can avoid radiation therapy. The salvage rate for the few relapses is high, with 100% survival overall.

Nodular lymphocyte predominant Hodgkin lymphoma: Clincopathological study of 25 cases from Japan with a reappraisal of tissue associated macrophages

Clinicopathological features of 25 nodular lymphocyte predominant Hodgkin lymphoma (NLPHL) patients in Japan were analysed. To investigate the clinicopathological significance of tissue associated macrophages (TAM) in NLPHL, CD68 and CD163 expression were investigated. The median age at onset was 56 years (range: 6-82 years) with male predominance (64%). All patients presented with lymph node enlargement with predilection for cervical LNs. Seven cases (28%) had mediastinal lesion and four (16%) had extranodal involvement. Most cases (76%) presented with early clinical stages. After median follow up of 44 months, both of overall and progression free survival rates were 95%. The presence of >5% CD68+ TAM in NLPHL was significantly associated with older age at diagnosis (median, 71 vs 52.5 years; P = 0.048), lower hemoglobin level (33.3% vs 0%; P = 0.037) and lower CR rate after initial treatment (42.9% vs 91.7%; P = 0.038). The presence of >5% CD163+ TAM was significantly correlated with presence of B symptoms (40% vs 0%; P = 0.036). In conclusion, NLPHL is rare among Japanese and appears to present at an older age than among Western patients. In our series, the presence of >5% CD68+ TAM in NLPHL was associated with lower CR rate, but with no impact on patients' survival.

CD20 Over-Expression in Hodgkin-Reed-Sternberg Cells of Classical Hodgkin Lymphoma: the Neglected Quest

We have scrutinized a previously analyzed cohort of classical Hodgkin lymphoma patients for evidence of a CD20 over-expression. This was pursued in order to determine whether all the 24 (12.6%) CD20+++ patients had clinical and/or biological profiles which would warrant a separate consideration and treatment or would carry a different outcome from our 166 CD20 (-) classical Hodgkin lymphoma patients. Except for an older age and a significantly lower expression of non-sialyl-CD15 antigen, both previously described in classical Hodgkin lymphoma, no justification to exclude these CD20+++ patients from the cohort at large is apparent. We suggest that the generally accepted view to the contrary be revised. In addition, we propose alternative interpretations for the low expression of CD20 found in a majority of Hodgkin-Reed-Sternberg cells in classical Hodgkin lymphoma.

FOXO1 downregulation contributes to the oncogenic program of primary mediastinal B-cell lymphoma

Recently we have shown that the transcription factor FOXO1, highly expressed in B cells, is downregulated in classical Hodgkin lymphoma (cHL). As primary mediastinal B cell lymphoma (PMBL) has similarities with the cHL transcription program we investigated FOXO1 expression in this entity. By using immunohistochemistry we found that FOXO1 was absent or expressed at low levels in 19 of 20 primary PMBL cases. PMBL cell lines reproduce the low FOXO1 expression observed in primary cases. By analyzing gene expression profiling data we found that FOXO1 expression inversely correlated with JAK2 in PMBL cases. Targeting JAK2 activity by the small molecular weight inhibitor TG101348 resulted in upregulation of FOXO1 mRNA and protein expression in MedB-1 and U2940 cell lines, and the MYC inhibitor 10058-F4 increased FOXO1 mRNA in MedB-1 cells. Moreover, in MedB-1 cells FOXO1 expression was strongly upregulated by the inhibitor of DNA methylation 5-aza-2-deoxycytidine and by the histone deacetylase inhibitor trichostatin A. Since FOXO1 promoter was unmethylated, this effect is most likely indirect. FOXO1 activation in the FOXO1-negative MedB-1 cell line led to growth arrest and apoptosis, which was accompanied by repression of MYC and BCL2L1/BCLx_L. Thus, FOXO1 repression might contribute to the oncogenic program and phenotype of PMBL.

Practical Applications in Immunohistochemistry: Evaluation of Diffuse Large B-Cell Lymphoma and Related Large B-Cell Lymphomas

Context

Diffuse large B-cell lymphoma is the most commonly diagnosed subtype of lymphoma worldwide. The current World Health Organization (WHO) classification includes several subtypes, based on a combination of clinical, immunohistochemical, and genetic differences. Immunohistochemical staining is essential in evaluating diffuse large B-cell lymphoma and many related large B-cell lymphomas and aggressive B-cell lymphomas.

Objective

To address different immunohistochemical features used for identification, subclassification, prognosis and in some cases, therapy, of diffuse large B-cell lymphoma and related lymphomas.

Data Sources

The information outlined in this review article is based on our experiences with routine cases, on the current WHO classification of hematopoietic and lymphoid tumors, and on a review of English-language articles published throughout 2014.

Conclusions

Features and diagnostic criteria of diffuse large B-cell lymphoma, aggressive variants of B-cell lymphomas, including Burkitt lymphoma and “double-hit” lymphomas, are discussed. Identification of cell of origin (germinal center type versus activated B-cell type) is discussed at length. Finally, practical approaches for diagnosis are discussed.

Fatal necrotizing angiotropic Epstein-Barr virus-negative large B-cell lymphoma: a case report with unusual clinicopathological features in-between lymphomatoid granulomatosis and T-cell/histiocyte-rich large B-cell lymphoma

In the spectrum of diffuse large B-cell lymphomas (DLBCL), both T-cell/histiocyte-rich large B-cell lymphoma (TCHRBCL) and most lymphomatoid granulomatosis (LG) cases are characterized by the relative rarity of the neoplastic B-cell population, with respect to the overwhelming non-neoplastic counterpart of T cells or histiocytes. Here we report a case of aggressive B-cell lymphoma with unusual clinicopathological features partially overlapping these two entities. The patient was a previously healthy 55-year-old male, presenting with a computed tomography finding of a pelvic mass, inguinal lymphadenopathies, and pulmonary nodules. Two excisional lymph node biopsies resulted inconclusive for lymphoproliferative disease. Because of a colonic perforation, the patient underwent an urgent laparotomy, which disclosed a large pelvic abscess. The pathological examination of the surgical specimen could not discriminate between a primary aggressive B-cell lymphoproliferative disorder and an abnormal inflammatory hyper-reaction. The patient developed a septic state, not resolving until death, which occurred because of an abdominal hemorrhage. A second perimortem surgical specimen consisting of a nodal mass revealed a diagnosis of an Epstein-Barr virus-negative high-grade large B-cell lymphoma with massive necrosis, angiocentric pattern of growth, and prominent T-cell infiltrate. The unique clinicopathological features did not allow to classify this tumor within any of the recognized WHO entities, potentially representing a new clinicopathological variant of DLBCL in-between TCHRBCL and LG.

Primary mediastinal large B-cell lymphoma

Primary mediastinal B-cell lymphoma (PMBCL) is a relatively rare lymphoma subtype affecting mainly young adults. Its molecular signature and clinical features resemble classical Hodgkin lymphoma. The optimal chemotherapy for this lymphoma subtype has not been established. The addition of rituximab to anthracycline based chemotherapy improved response rates and survival. Many centers use R-CHOP as standard treatment, but the role of the intensified regimens and consolidation radiotherapy has to be clarified. Recent data coming from retrospective analyses and an ongoing prospective study addressing the problem of consolidation radiotherapy will help to better identify risk groups and apply risk-adapted and effective treatment strategies. The latest research has helped to understand molecular mechanisms of PMBCL pathogenesis and indicated targets of directed therapy for the future.

Nodular Lymphocyte Predominant Hodgkin Lymphoma versus T-Cell/Histiocyte-Rich Large B-Cell Lymphoma: A Diagnostic Challenge

Lymphomas with overlapping histological features of two distinct entities cause difficulty in classification. Their classification is of particular significance when the two alternatives require different treatment modalities. We present a diagnostically challenging case of a nodular lymphocyte predominant Hodgkin lymphoma (NLPHL) with features of T-cell/histiocyte-rich large B-cell lymphoma (THRLBCL). Our patient is a 39-year-old woman who presented with painless subclavicular and axillary lymphadenopathy. The biopsied lymph node showed diffuse architectural effacement and scattered large neoplastic cells with large irregular nuclei and prominent nucleoli. These cells were positive for CD20 and Bcl-6 and negative for CD15, CD30, IgD, and Bcl-2. The background cells were predominantly T lymphocytes, whereas B cells were markedly depleted. The lymph node was interpreted as NLPHL, consistent with THRLBCL-like variant. NLPHL, especially THRLBC-like variant, and de novo THRLBCL are characterized by significant morphologic and immunophenotypic overlap. Our case demonstrates a rare predominance of background T-cells in NLPHL and emphasizes the importance of thorough evaluation of multiple morphologic and immunophenotypic features as an essential approach for arriving at the correct diagnosis.

Hodgkin lymphoma: pathology, pathogenesis, and a plethora of potential prognostic predictors

Hodgkin lymphoma (HL) encompasses 2 unique clinicopathologic entities, classical Hodgkin lymphoma (CHL) (∼95% of cases) and nodular lymphocyte predominant HL (∼5% of cases). Both subtypes demonstrate a paucity of surreptitious (in CHL) neoplastic B cells within a background of reactive inflammatory cells underscoring both the relatedness of these 2 entities to each other, as well as their distinction from other types of lymphoid neoplasia. Clinically, they are primarily nodal diseases that disseminate in a predictable manner to contiguous nodal regions. The biology of HL as a whole, as well as the genetic and pathologic features that distinguish CHL from nodular lymphocyte predominant HL and other lymphomas has been the subject of a wealth of investigation in recent decades. The aim of this review is to detail the pathologic features of HL and to highlight the recent insights into its molecular basis and the myriad prognostic markers being described.

How I treat nodular lymphocyte predominant Hodgkin lymphoma

Nodular lymphocyte predominant Hodgkin lymphoma (NLPHL) is an uncommon entity that, in contrast to classical Hodgkin lymphoma (cHL), universally expresses CD20, a hallmark of the disease. The majority of the patients present with early-stage disease, and treatment with local radiation provides excellent disease control and overall survival (OS). For locally extensive or advanced stages, paradigms used for cHL have been employed, with similar outcomes. Unlike cHL, late relapses may occur, as well as a propensity to transform to an aggressive B-cell non-Hodgkin lymphoma that underscores the importance of long-term follow-up and rebiopsy at the time of relapse. Deaths caused by NLPHL are uncommon, and in older series, secondary malignancies and other treatment-related toxicities contributed appreciably to overall mortality. Expression of CD20 in NLPHL has led to the evaluation of rituximab as a therapeutic option. Although results with single-agent rituximab in the front-line setting are inferior to conventional therapy, rituximab is a reasonable choice for relapsed disease because of the high overall response rate and excellent tolerability. Most patients have a long OS; therefore, overall goals of therapy should be to minimize the risk for relapse and long-term toxicity.

Biostable ssDNA aptamers specific for Hodgkin lymphoma

As a "chemical antibody", oligonucleotide aptamers can specifically bind to their target molecules. However, clinical potential of aptamers in disease diagnosis is not yet fully explored. Using a tumor cell-based selection protocol, we developed single-stranded DNA aptamers for Hodgkin lymphoma (HL) tumor cells. The aptamers specifically bound to HL cells with a high affinity, reaching maximal cell binding at 10 nM final concentration. Importantly, the aptamers were able to selectively detect HL cells and did not react to other tumor or blood cells in mixed samples, indicating that the aptamers can be used as a specific probe for in vitro analysis of HL cells. Moreover, due to the inherent properties of DNA, the aptamers were stable in human serum, suggesting potential for in vivo detection of HL tumor cells.

PD-L1 expression is characteristic of a subset of aggressive B-cell lymphomas and virus-associated malignancies

PURPOSE

Programmed cell death ligand 1 (PD-L1) is an immunomodulatory molecule expressed by antigen-presenting cells and select tumors that engages receptors on T cells to inhibit T-cell immunity. Immunotherapies targeting the PD-1/PD-L1 pathway have shown durable antitumor effects in a subset of patients with solid tumors. PD-L1 can be expressed by Reed-Sternberg cells comprising classical Hodgkin lymphoma (CHL) and by malignant B cells comprising EBV-positive posttransplant lymphoproliferative disorders (PTLD). We sought to determine whether the expression of PD-L1 represents a general strategy of immune evasion among aggressive B-cell lymphomas and virus- and immunodeficiency-associated tumors.

EXPERIMENTAL DESIGN

Using novel antibodies and formalin-fixed, paraffin-embedded (FFPE) tissue biopsies, we examined 237 primary tumors for expression of PD-L1.

RESULTS

Robust PD-L1 protein expression was found in the majority of nodular sclerosis and mixed cellularity CHL, primary mediastinal large B-cell lymphoma, T-cell/histiocyte-rich B-cell lymphoma, EBV-positive and -negative PTLD, and EBV-associated diffuse large B-cell lymphoma (DLBCL), plasmablastic lymphoma, extranodal NK/T-cell lymphoma, nasopharyngeal carcinoma, and HHV8-associated primary effusion lymphoma. Within these tumors, PD-L1 was highly expressed by malignant cells and tumor-infiltrating macrophages. In contrast, neither the malignant nor the nonmalignant cells comprising nodular lymphocyte-predominant Hodgkin lymphoma, DLBCL-not otherwise specified, Burkitt lymphoma, and HHV8-associated Kaposi sarcoma expressed detectable PD-L1.

CONCLUSION

Certain aggressive B-cell lymphomas and virus- and immunodeficiency-associated malignancies associated with an ineffective T-cell immune response express PD-L1 on tumor cells and infiltrating macrophages. These results identify a group of neoplasms that should be considered for PD-1/PD-L1-directed therapies, and validate methods to detect PD-L1 in FFPE tissue biopsies.

Whole genome profiling and other high throughput technologies in lymphoid neoplasms--current contributions and future hopes

The development of high throughput technologies based on the knowledge of the human genome has opened the possibility to search for global genomic alterations in tumors responsible for their development and progression that may have important clinical implications. One of the major applications of this genomic knowledge has been the design of different types of microarray platforms for the analysis of DNA alterations and gene expression profiling (GEP). The main contributions of the DNA studies in lymphoid neoplasms include the definition of relatively characteristic genomic profiles for specific disease entities, the demonstration of common chromosomal alterations across entities, the identification of genes and pathways targeted by the altered chromosomal regions, and the identification of chromosomal alterations with prognostic implications. RNA GEP studies in these tumors have enhanced the molecular characterization of known entities and facilitated the recognition of new subtypes and categories of lymphoid neoplasms, the identification of new biomarkers and prognostic models, and the detection of oncogenic pathways with potential implications for targeted therapies. The recent development of the next generation sequencing (NGS) technologies and its application in lymphoid neoplasms already have provided an initial view of the complex landscape of somatic mutations in these tumors and some findings with important functional and clinical implications. This review addresses the major contributions and limitations of the microarray technologies in the understanding of lymphoid neoplasms and discusses how this knowledge may be transferred into the clinics. The initial results of the NGS studies are also presented.