Nodular lymphocyte-predominant hodgkin lymphoma with atypical T cells: a morphologic variant mimicking peripheral T-cell lymphoma

Triple Lymphoma and Transformation to Diffuse Large B-Cell Lymphoma Finding at the Time of Diagnosis

In this report, we present the case of a patient with an uncommon triple diagnosis of (1) follicular (nodular) lymphoma, (2) nodular lymphocyte predominant Hodgkin lymphoma, and (3) diffuse large B-cell lymphoma non-germinal center B-cell (non-GCB) subtype. Although transformation of follicular lymphoma and nodular lymphocyte predominant lymphoma to more aggressive forms such as diffuse large B-cell lymphoma is possible; it generally happens many years after diagnosis. Moreover, there have been reported cases of follicular lymphoma with transformation and nodular lymphocyte predominant Hodgkin lymphoma with transformation at the time of diagnosis, but it is very uncommon to see all three present on initial diagnosis. Our patient presented with a large right axillary mass, which, upon excisional biopsy and subsequent histology, showed the aforementioned lymphomas. The patient did not present with a prodrome of any symptoms except intermittent night sweats. The unique aspect of our case is that transformation and all three lymphomas were seen at the time of diagnosis. The R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone) chemotherapy regimen is still the standard method of treatment as it has been shown to be effective in treating follicular lymphoma and nodular lymphocyte predominant Hodgkin lymphoma with and without transformation. However, there is insufficient literature on its efficacy when all three are present concurrently.

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.

Hodgkin Lymphoma: Biology and Differential Diagnostic Problem

Hodgkin lymphomas (HLs) are lymphoid neoplasms that are morphologically defined as being composed of dysplastic cells, namely, Hodgkin and Reed–Sternberg cells, in a reactive inflammatory background. The biological nature of HLs has long been unclear; however, our understanding of HL-related genetics and tumor microenvironment interactions is rapidly expanding. For example, cell surface overexpression of programmed cell death 1 ligand 1 (CD274/PD-L1) is now considered a defining feature of an HL subset, and targeting such immune checkpoint molecules is a promising therapeutic option. Still, HLs comprise multiple disease subtypes, and some HL features may overlap with its morphological mimics, posing challenging diagnostic and therapeutic problems. In this review, we summarize the recent advances in understanding the biology of HLs, and discuss approaches to differentiating HL and its mimics.

Critical Role of Flow Cytometric Immunophenotyping in the Diagnosis, Subtyping, and Staging of T-Cell/NK-Cell Non-Hodgkin's Lymphoma in Real-World Practice: A Study of 232 Cases From a Tertiary Cancer Center in India

Background

T-cell/NK-cell non-Hodgkin’s lymphoma (T/NK-NHL) is an uncommon heterogeneous group of diseases. The current classification of T/NK-NHL is mainly based on histopathology and immunohistochemistry. In practice, however, the lack of unique histopathological patterns, overlapping cytomorphology, immunophenotypic complexity, inadequate panels, and diverse clinical presentations pose a great challenge. Flow cytometric immunophenotyping (FCI) is a gold standard for the diagnosis, subtyping, and monitoring of many hematological neoplasms. However, studies emphasizing the role of FCI in the diagnosis and staging of T/NK-NHL in real-world practice are scarce.

Methods

We included T-cell non-Hodgkin’s lymphoma (T-NHL) patients evaluated for the diagnosis and/or staging of T/NK-NHL using FCI between 2014 and 2020. We studied the utility of FCI in the diagnosis and subtyping of T/NK-NHL and correlated the FCI findings with the results of histopathology/immunohistochemistry. For correlation purposes, patients were categorized under definitive diagnosis and subtyping, inadequate subtyping, inadequate diagnosis, and misdiagnosis based on the findings of each technique.

Results

A total of 232 patients were diagnosed with T/NK-NHL. FCI findings provided definitive diagnoses in 198 patients and subtyping in 187/198 (95.45%) patients. The correlation between FCI and histopathological/immunohistochemistry results (n = 150) demonstrated an agreement on the diagnosis and subtyping in 69/150 (46%) patients. Of the remaining cases, the diagnosis and subtyping were inadequate in 64/150 (42.7%), and 14/150 (9.33%) were misdiagnosed on histopathology/immunohistochemistry results. FCI provided definitive diagnosis and subtyping in 51/64 (79.7%) patients. Among these, 13 patients diagnosed with peripheral T-cell lymphoma not-otherwise-specified were reclassified (angioimmunoblastic T-cell lymphoma (AITL)-11 and prolymphocytic leukemia-2) on FCI. It corrected the diagnosis in 14 patients that were misdiagnosed (6 B-cell NHL (B-NHL), 3 Hodgkin’s lymphoma, 1 acute leukemia, and 1 subcutaneous panniculitis-like T-cell lymphoma) and misclassified (3 T-NHL) on histopathological results. AITL was the commonest T-NHL misclassified on histopathological results. FCI also confirmed the definite involvement in 7/83 (8.4%) and 27/83 (32.5%) bone marrow (BM) samples reported as suspicious and uninvolved, respectively, on histopathological evaluation.

Conclusion

AITL was the most frequently diagnosed T/NK-NHL in this study. FCI provided a distinct advantage in detecting BM involvement by T/NK-NHL, especially in patients with low-level involvement. Overall, our study concluded that FCI plays a critical role in the diagnosis, subtyping, and staging of T/NK-NHL in real-world practice.

Geographic Variability of Nodular Lymphocyte-Predominant Hodgkin Lymphoma

OBJECTIVES

Nodular lymphocyte-predominant Hodgkin lymphoma (NLPHL) differs from classic Hodgkin lymphoma (CHL) in terms of clinicopathologic features, including Epstein-Barr virus (EBV) association. CHL geographic variability is well known, with higher frequencies of mixed-cellularity subtype and EBV positivity in low/middle-income countries (LMICs), but there are few well-characterized series of NLPHL from LMICs.

METHODS

We detail clinicopathologic findings of 21 NLPHL cases received in consultation from Kenya and summarize reports of NLPHL with EBV testing published since 2000.

RESULTS

Median age of consultation cases was 36 years, and male/female ratio was 3.2. All cases involved peripheral lymph nodes and showed at least some B-cell-rich nodular immunoarchitecture, with prominent extranodular lymphocyte-predominant (LP) cells and T-cell-rich variant patterns most commonly seen. LP cells expressed pan-B-cell markers, including strong OCT2; lacked CD30 and CD15 expression in most cases; and were in a background of expanded/disrupted follicular dendritic cell meshworks and increased T-follicular helper cells. LP cells were EBV negative in 18 cases. Historical cases showed a low rate of EBV positivity with no significant difference between LMICs and high-income countries.

CONCLUSIONS

Unlike CHL, NLPHL shows few geographic differences in terms of clinicopathologic features and EBV association. These findings have implications for diagnosis, prognostication, and treatment of patients with NLPHL in LMICs.

Update on Pediatric and Young Adult Mature Lymphomas

After acute leukemia and brain and central nervous system tumors, mature lymphomas represent the third most common cancer in pediatric patients. Non-Hodgkin lymphoma accounts for approximately 60% of lymphoma diagnoses in children, with the remainder representing Hodgkin lymphoma. Among non-Hodgkin lymphomas in pediatric patients, aggressive lymphomas, such as Burkitt lymphoma, diffuse large B-cell lymphoma, and anaplastic large cell lymphoma, predominate. This article summarizes the epidemiologic, histopathologic, and molecular features of selected mature systemic B-cell and T-cell lymphomas encountered in this age group.

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

Simple Summary

Nodular lymphocyte predominant Hodgkin lymphoma (NLPHL) is a rare lymphoma containing infrequent tumor cells (LP cells) in a background of non-neoplastic cells. Some cases of NLPHL can recur or progress to a more aggressive lymphoma, such as diffuse large B-cell lymphoma. Awareness of the different appearances of NLPHL and its overlap with other lymphomas are important for the appropriate diagnosis, classification and research. This article discusses the conceptual framework and guidelines for the diagnosis of NLPHL, and how NLPHL can be best separated from its mimics. Emerging data in the field point to genetic changes in LP cells that are shaped by immune mechanisms. In addition, non-neoplastic cells in the background of LP cells also appear to play an important role. Further investigation is necessary to fully understand the biology of NLPHL and personalize cancer care for patients affected by this lymphoma.

Abstract

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.

Overlap between EBV-positive diffuse large B-cell lymphoma, NOS, in a young patient and angioimmunoblastic T-cell lymphoma: A diagnostic pitfall

There may be significant histopathologic overlap between EBV-positive DLBCL, NOS, and other diagnoses including angioimmunoblastic T-cell lymphoma (AITL). Resolution of this differential diagnosis may be particularly challenging and require extensive investigation of clinicopathologic features.

Limited Tissue Biopsies and Hematolymphoid Neoplasms

OBJECTIVES

Use of fine-needle aspiration/needle core biopsy (FNA/CNB) in evaluating hematolymphoid processes has been debated. We investigate its applicability in various clinicopathologic settings.

METHODS

We retrospectively analyzed 152 cases of FNA/CNB.

RESULTS

Of 152 FNA/CNBs, 124 (81.6%) resulted in diagnoses without excisional biopsies, while 28 required subsequent excisional biopsies. Of these, 43 FNA/CNBs performed for suspected lymphoma relapse demonstrated 95.4% diagnostic rate (41/43), which was significantly better than those without history of lymphoma (77/109, 71%; odds ratio [OR], 8.5; confidence interval, 1.9-37.4). Patients with immunodeficiency also showed a high rate of diagnosis by FNA/CNB (100%). When stratified by types of disease, diffuse large B-cell lymphoma/high-grade B-cell lymphoma demonstrated a higher success rate (92.7%) than small B-cell lymphoma (79.2%), though the difference was not statistically significant (OR, 3.3; P value = .07). A subsequent excisional biopsy was required in 28 cases, 23 of which resulted in diagnoses concordant with the FNA/CNB. Five cases showed diagnostic discordance, reflecting pitfalls of FNA/CNB in unusual cases with complex pathology.

CONCLUSIONS

FNA/CNB is practical in evaluating most hematolymphoid lesions, with high efficacy in recurrent disease and some primary neoplasms with homogeneous/ aggressive histology, or characteristic immunophenotype.

Diagnosis of Hodgkin lymphoma in the modern era

The Hodgkin lymphomas are a family of unique lymphoma subtypes, in which the nature of the neoplastic cell was enigmatic for many years. Much of the mystery has been solved, with all forms now considered to be of B-cell origin, in most cases of germinal centre derivation. Today we recognize Hodgkin lymphoma as an eponym that encompasses multiple entities. One of the unifying themes is the major contribution from the tumour microenvironment. Both the character of the neoplastic cells and the nature of the immune environment are critical to accurate diagnosis. Moreover, an understanding of the molecular alterations that characterize both the neoplastic cells and their microenvironment have led to therapeutic advances, targeting both neoplastic and reactive components. Other conditions may foster a similar inflammatory milieu and lead to lymphoproliferations that mimic the Hodgkin lymphomas. In this review we provide an update on the diagnostic features of the various subtypes and include additional information relevant for prognostic evaluation and investigation of potential therapeutic targets. Additionally, we also discuss those conditions that often cause confusion in diagnosis and need to be distinguished from the Hodgkin lymphomas.

Use of flow cytometry in the phenotypic diagnosis of hodgkin's lymphoma

Hodgkin's lymphoma (HL) has a unique immunophenotype derived from immunohistochemistry (positive for CD15, CD30, and Pax-5; negative for CD3, CD20 in most cases, and CD45). The knowledge gained over recent years enables better diagnosis, prognosis, and treatment of HL. Flow cytometry as a tool for the diagnosis of classic HL has not been useful in the past due to the difficulty in isolating Reed-Sternberg cells as they are admixed in a rich inflammatory background which consists mainly of T cells, B cells, eosinophils, histiocytes, and plasma cells. However, in the recent past, several studies have tried to identify Reed-Sternberg cells using flow cytometry on fine needle aspiration or tissue biopsy of lymph nodes to confirm or supplement immunohistochemistry staining in diagnosis. Newer and more sensitive tools such as flow cytometry can be used for diagnosis, technology that may have been difficult in the past for diagnosis of this lymphoma subtype. Using flow cytometry, diagnosis is faster and could lead to point-of-care technology especially where we have typical immunophenotype signatures. © 2018 International Clinical Cytometry Society.

Composite lymphoma of peripheral T-cell lymphoma and Hodgkin lymphoma, mixed cellularity type; pathological and molecular analysis

Composite lymphomas (CLs) are defined as two unrelated lymphomas occurring at the same time within the same tissue. The incidence of these tumors is low. Of all possible combinations between lymphomas, the least frequent are the ones combining peripheral T-cell lymphoma (PTCL) and Hodgkin lymphoma (HL). We recently identified five cases of CL composed of PTCL and classical HL, mixed cellularity type. We investigated histological and clinical features of these cases. Immunostaining was performed on paraffin sections. PTCL cells were positive for CD8 and TIA-1 in four of the five cases. Hodgkin and Reed-Sternberg (HRS) cells were positive for CD30 and weakly positive for PAX5 in all cases, positive for CD15 in three of five cases, positive for CD20 in one of five cases, and negative for EBER. Monoclonal rearrangement of the T-cell receptor (TCR) and immunoglobulin heavy chain (IGH) genes was confirmed by polymerase chain reaction (PCR) using whole paraffin sections. We concluded more precisely the monoclonality of the IGH rearrangement of HRS cells based on single-cell PCR for IGH and DNA sequencing analysis after laser microdissection of single cells in one case. HL can occur in CD8-positive and TIA-1-positive PTCL. Clinicians should recognize the possibility of these CL.

Characterization and Purification of Neoplastic Cells of Nodular Lymphocyte Predominant Hodgkin Lymphoma from Lymph Nodes by Flow Cytometry and Flow Cytometric Cell Sorting

We report the flow cytometric (FC) identification and characterization of lymphocyte predominant (LP) cells from tissues involved by nodular lymphocyte predominant Hodgkin lymphoma (NLPHL). First, we immunophenotyped the NLPHL cell line (DEV) confirming a germinal center immunophenotype, lack of expression of CD32 and CD58, and expression of CD54. Nineteen of 26 lymph nodes involved by NLPHL demonstrated a population with an LP immunophenotype (73%), which included expression of germinal center markers (CD75/Bcl-6-positive, CD32-weak/negative without CD10), a B-cell immunophenotype (CD19/CD20/CD40⁺), IgD and/or IgM expression (67%), and lack of programmed death-ligand 1/ligand 2. The LP cells demonstrated an adhesion macromolecule expression pattern distinct from Hodgkin and Reed-Sternberg cells of classical Hodgkin lymphoma (CHL) (uniform CD50 and variable CD58 for NLPHL; minimal CD50, bright CD58 expression for CHL). A two-tube consensus assay identified LP cells in all seven NLPHL cases examined and only one non-NLPHL case (94 cases evaluated). Finally, FC cell sorting studies confirm that FC-defined populations have an LP cytomorphology. Taken together, these findings demonstrate a two-tube consensus assay can be used to immunophenotype NLHPL with high specificity and sensitivity and rapidly purify LP cells for genetic studies. This study also confirms aneuploidy in LP cells, provides antigens that may be helpful in distinguishing NLPHL from CHL, and suggests that T cells interact less avidly with LP cells than with Hodgkin and Reed-Sternberg cells.

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.

Nodular lymphocyte-predominant Hodgkin lymphoma

Nodular lymphocyte-predominant Hodgkin lymphoma (NLPHL) is a rare subtype of Hodgkin lymphoma with distinct clinicopathologic features. It is typified by the presence of lymphocyte predominant (LP) cells, which are CD20(+) but CD15(-) and CD30(-) and are found scattered amongst small B lymphocytes arranged in a nodular pattern. Despite frequent and often late or multiple relapses, the prognosis of NLPHL is very favorable. There is an inherent risk of secondary aggressive non-Hodgkin lymphoma (NHL) and studies support that risk is highest in those with splenic involvement at presentation. Given disease rarity, the optimal management is unclear and opinions differ as to whether treatment paradigms should be similar to or differ from those for classical Hodgkin lymphoma (CHL). This review provides an overview of the existing literature describing pathological subtypes, outcome and treatment approaches for NLPHL.

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.

Childhood and Adolescent nodular lymphocyte predominant Hodgkin lymphoma - A review of clinical outcome based on the histological variants

Nodular lymphocyte predominant Hodgkin lymphoma (nLPHL) comprises approximately 10-12% of all childhood Hodgkin lymphoma. As the majority have low stage disease recent years have seen a de-escalation of treatment intensity to avoid treatment-related morbidity. This report evaluates treatment outcome in children with histopathological variants of nLPHL after therapy de-escalation. Biopsies from 60 patients were reviewed and histology categorized as typical (n = 47; 78%) or variant nLPHL (n = 13; 22%). Furthermore, presence of immunoglobulin D (IgD) expression by the lymphocyte predominant (LP) cells was assessed in 41 patients. Treatment outcomes were compared according to treatment received and histopathology of nLPHL. Compared to typical nLPHL, children with variant nLPHL had higher stage disease at diagnosis (stage III: 3/13; 23% vs. 3/47; 6%, P = 0·11), lower complete response rates (6/13; 46% vs. 38/47; 81%, P = 0·029) and higher relapse rates (2/13; 15% vs. 2/47; 4%, P = 0·20). Additionally, IgD expression by LP cells was associated with poorer treatment response and was more commonly seen in patients with variant nLPHL. (11/13; 85% vs. 15/28; 54%, P = 0·08). Variant histology appears to be indicative of a poorer prognosis in patients with early stage disease, and may be an important factor to take into account when moving towards reduced intensity treatment for nLPHL.

Automatic lymphoma classification with sentence subgraph mining from pathology reports

OBJECTIVE

Pathology reports are rich in narrative statements that encode a complex web of relations among medical concepts. These relations are routinely used by doctors to reason on diagnoses, but often require hand-crafted rules or supervised learning to extract into prespecified forms for computational disease modeling. We aim to automatically capture relations from narrative text without supervision.

METHODS

We design a novel framework that translates sentences into graph representations, automatically mines sentence subgraphs, reduces redundancy in mined subgraphs, and automatically generates subgraph features for subsequent classification tasks. To ensure meaningful interpretations over the sentence graphs, we use the Unified Medical Language System Metathesaurus to map token subsequences to concepts, and in turn sentence graph nodes. We test our system with multiple lymphoma classification tasks that together mimic the differential diagnosis by a pathologist. To this end, we prevent our classifiers from looking at explicit mentions or synonyms of lymphomas in the text.

RESULTS AND CONCLUSIONS

We compare our system with three baseline classifiers using standard n-grams, full MetaMap concepts, and filtered MetaMap concepts. Our system achieves high F-measures on multiple binary classifications of lymphoma (Burkitt lymphoma, 0.8; diffuse large B-cell lymphoma, 0.909; follicular lymphoma, 0.84; Hodgkin lymphoma, 0.912). Significance tests show that our system outperforms all three baselines. Moreover, feature analysis identifies subgraph features that contribute to improved performance; these features agree with the state-of-the-art knowledge about lymphoma classification. We also highlight how these unsupervised relation features may provide meaningful insights into lymphoma classification.

Large B-cell lymphomas poor in B cells and rich in PD-1+ T cells can mimic T-cell lymphomas

OBJECTIVES

To characterize the clinicopathologic features of cases of large B-cell lymphomas, poor in B cells and densely rich in programmed cell death-1 (PD-1)+ reactive T cells, which can mimic T-cell lymphomas.

METHODS

A single-institute retrospective review of cases between 2010 and 2013 was performed.

RESULTS

Of 178 cases of large B-cell lymphomas, eight cases of large B-cell lymphomas poor in B cells and diffusely rich in sheets of PD-1+ T cells were identified. These cases either were initially misdiagnosed as a T-cell lymphoma or substantiated a broader differential diagnosis including a T-cell lymphoma. Five cases were T-cell histiocyte-rich large B-cell lymphomas, and three cases were diagnosed as large B-cell lymphomas rich in T cells. In three of these cases, a subset of the PD-1+ T cells showed either morphologic nuclear atypia or atypical expression of T-cell antigens on flow cytometry and/or immunohistochemistry.

CONCLUSIONS

Large B-cell lymphomas poor in B cells and rich in T cells can have diffuse sheets of reactive PD-1+ T cells, some with atypical morphologic and immunophenotypic features mimicking a T-cell lymphoma. Careful assessment of the immunoarchitecture and background inflammatory and stromal cells can prevent erroneous diagnoses in such cases.

The prognostic impact of variant histology in nodular lymphocyte-predominant Hodgkin lymphoma: a report from the German Hodgkin Study Group (GHSG)

Histopathologic variants of nodular lymphocyte–predominant Hodgkin lymphoma are associated with advanced stage and increased relapse rate. A prognostic score combining histopathologic and clinical features can allocate patients to 3 defined risk groups.

Clonality testing of malignant lymphomas with the BIOMED-2 primers in a large cohort of 1969 primary and consultant biopsies

The introduction of the BIOMED-2 primers allowed for reliable comparisons of clonality testing data of malignant lymphomas from different laboratories. This study undertook a retrospective analysis of a large cohort of cases; 1862 cases involved the immunoglobulin heavy chain locus (IGH VH-JH), and 1527 cases involved the T cell receptor gamma locus (TCRG). We confirmed previously published clonality rates in various B cell, T cell, and Hodgkin lymphoma cases. In reactive lesions, clonality for the IGH locus was frequently accompanied by additional polyclonal background. Clonality for TCRG was found in a subgroup of diffuse large B cell lymphomas. On closer morphologic inspection, seven cases appeared to have arisen from an underlying peripheral T-cell lymphoma. Five cases with monoclonal TCRG rearrangements, originally diagnosed as Hodgkin lymphomas, were reclassified as T-cell lymphomas. TCRG clonality was very rarely only observed in Hodgkin lymphoma. In case of clear TCRG clonality a T-cell neoplasia must be ruled out on morphological grounds. By careful examination of the rearrangement patterns, including an assessment of a co-amplified polyclonal background, clonality testing provides a powerful tool which in concert with morphologic and immunohistochemical parameters can lead to a firm diagnosis.

Intranodular clusters of activated cells with T follicular helper phenotype in nodular lymphocyte predominant Hodgkin lymphoma: a pilot study of 32 cases from Finland

In nodular lymphocyte predominant Hodgkin lymphoma (NLPHL), little is known about the presence of intranodular clusters of cytologically activated lymphoid cells producing a moth-eaten pattern histologically. This pilot study of 32 NLPHL cases from Finland ascertained (1) the frequency of the intranodular clusters of activated lymphoid cells, (2) the immunophenotype of the activated cells, (3) the size and immunophenotype of the rosetting cells, and (4) the clinical significance of the activated cells. Histologically, intranodular clusters of activated cells produced a moth-eaten pattern in 100% (32 cases; subtle in 62.5%, overt in 37.5%). In immunostains, activated cells in subtle clusters (20 cases) were very difficult to identify. Twelve cases had overt clusters of activated cells, which were positive with CD3, CD4, PD1, CXCL13 (T follicular helper [T(FH)] phenotype), but rarely with Ki-67 and BCL2. Most activated rosetting cells had the same immunophenotype as the nonrosetting cells, except for CXCL13. Clinical presentation for all 32 Finnish patients was distinctive: 97% men, 97% with peripheral lymphadenopathy and 35.5% with stage III/IV disease. Only 22% relapsed; 97% were in remission. There was no significant clinical difference between cases with overt and subtle clusters. Intranodular activated TFH cells in NLPHL appeared to be nonproliferating and not long-living, and they were not associated with any adverse clinical outcome. Although most activated cells were TFH cells, it seemed that they were unable to increase the number of malignant cells. The pathogenetic role of the intranodular activated TFH and the small T cells in NLPHL needs further investigation.

[Nodular lymphocyte-predominant Hodgkin's lymphoma and differential diagnoses]

Nodular lymphocyte-predominant Hodgkin's lymphoma (NLPHL) is a rare subtype of Hodgkin's lymphoma. The histological patterns of NLPHL variants are characterized by different localizations of the tumor cells, intranodular and perinodular and by the varying composition of the microenvironment. T-cell/histiocyte-rich B-cell lymphoma may be the result of an aggressive transformation of NLPHL. Classical lymphocyte-rich Hodgkin's lymphoma can usually be clearly distinguished from NLPHL by the immunophenotype of the tumor cells. Further differential diagnoses include follicular lymphoma and the follicular variant of peripheral T-cell lymphoma. Angioimmunoblastic T-cell lymphoma with CD20-positive blasts represents a differential diagnosis to the diffuse variants of NLPHL.

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

Hodgkin lymphomas (HLs) are neoplasms of large B cells. Two types are recognized: nodular lymphocyte predominant HL (NLPHL) and classical HL (CHL). In both types, there may be morphological and possibly biological overlap with large B-cell lymphomas (LBCLs) of non-HL types. These include nodular sclerosis CHL and primary mediastinal large B-cell lymphoma; CHL rich in lymphocytes and NLPHL; and NLPHL and T-cell/histiocyte-rich LBCL. This review covers the defining features of each of these diseases, the borderlines between them, and strategies for differential diagnosis.

Nodular lymphocyte predominant Hodgkin lymphoma in children and adolescents--a comprehensive review of biology, clinical course and treatment options

Nodular lymphocyte predominant Hodgkin lymphoma (nLPHL) is a unique variant of Hodgkin lymphoma with an overall good prognosis. It is conspicuously different from classical Hodgkin lymphoma (cHL) and is now recognized as distinctive form of B cell lymphoma. Although it has an indolent clinical course, it has a propensity for multiple and often late relapses. Although the majority of children present with early stage disease and without B symptoms, treatment strategy has, until recently, been identical to that used for cHL. This approach is excessively toxic as it predisposes these children and adolescents to serious late effects including end organ damage to heart, gonads, lungs, thyroid and second malignant neoplasms. The aim of this article is to review the published literature on the treatment outcomes of nLPHL in affected children and adolescents, and discuss the options for treatment including surgery, chemotherapy, radiotherapy and targeted anti-CD 20 antibody therapy.

Nodular lymphocyte predominance Hodgkin lymphoma of the parotid gland: a case report

The parotid is the most frequent site of primary salivary gland tumors. Lymphomas represent 0.2 to 0.8% of all malignant parotid tumors. Primary Hodgkin lymphoma of the parotid gland is rare with few cases reported in literature. The nodular lymphocyte predominance Hodgkin lymphoma (HL) is considered a particular clinical and histopathological subtype of HL. It has never been reported in the parotid gland since its incorporation in the 2001 World Health Organization Classification. The authors describe a case of a 32-year-old male who sought medical attention because of a one-year history of right cheek enlargement. A parotid nodule was submitted to a fine needle aspiration biopsy which disclosed a suspected lymphoproliferative disorder. A surgical dissection of the parotid gland was performed and an enlarged intraparotid lymph node measuring 4cm in its longest axis was excised, preserving the parotid gland integrity as well as the facial nerve. The pathological examination disclosed the diagnosis of nodular lymphocyte predominance Hodgkin lymphoma in this lymph node within the parotid gland. The treatment was completed with local radiotherapy and the 5-year follow up was uneventful.

Nodular lymphocyte-predominant Hodgkin lymphoma (NLPHL) with CD30-positive lymphocyte-predominant (LP) cells

Nodular lymphocyte-predominant Hodgkin lymphoma (NLPHL) is a distinct neoplasm within the spectrum of Hodgkin lymphomas with characteristic clinical, morphological, and immunohistochemical features. According to the WHO definition, lymph nodes involved by NLPHL should have a nodular or nodular and diffuse proliferation of scattered large neoplastic lymphocyte-predominant (LP) cells in a small cell background that reside in expanded follicular dendritic cell meshworks; the LP cells must also have a distinct immunophenotypic profile. The LP cells are monoclonal B cells that are typically CD20, BCL6, CD79a, and CD45 positive and are CD30 and CD15 negative. In contrast, the Reed-Sternberg cells of classical Hodgkin lymphoma (CHL) are typically positive for CD15 and CD30. However, in CHL, CD20 staining is variable, and CD15 staining may be absent in some cases. Thus, CD30 is often considered to be the most distinctive marker between CHL and NLPHL. In order to better assess CD30 staining in NLPHL, we reviewed 220 cases of NLPHL and found 21 cases that showed at least focal staining of the neoplastic cells for CD30. The CD30 staining was often faint, but occasionally strong, and typically was found only on a subset of the LP cells. We evaluated the clinicopathologic features of these cases to determine whether they showed differences from typical CD30-negative NLPHL and found no significant difference with respect to clinical presentation, histology, other immunophenotypic features or outcome. In summary, we conclude that CD30 expression by LP cells in NLPHL can be seen and should not lead to a misdiagnosis of CHL. The presence of CD30-positive LP cells is not associated with other features of CHL or unusually aggressive behavior.