A Review of the Flow Cytometric Findings in Classic Hodgkin Lymphoma, Nodular Lymphocyte Predominant Hodgkin Lymphoma and T Cell/Histiocyte-Rich Large B Cell Lymphoma

Classic Hodgkin lymphoma, nodular lymphocyte predominant Hodgkin lymphoma, and T cell/histiocyte-rich large B cell lymphoma form a unique set of lymphomas with similar morphologic growth patterns (occasional neoplastic cells within a prominent cellular cell background) that are pathobiologically related. Distinguishing these entities has been historically difficult by flow cytometry; however, our laboratory has developed antibody-fluorochrome combinations capable of immunophenotyping these lymphomas. Additionally, characterization of the background reactive lymphocytes can aid in narrowing the differential diagnosis. This review summarizes the immunophenotypic features and insights of the neoplastic and reactive populations found in this unique group of lymphomas.

[Strategy of the French Society of Childhood Cancer (SFCE) for pediatric nodular lymphocyte predominant lymphoma]

Nodular Lymphocyte predominant Hodgkin lymphoma (NLPHL) are rare lymphomas in pediatric patients comprising less than 10 % of all Hodgkin lymphoma (HL). They are for the most part diagnosed at stage I or II and indolent with lymphadenopathy often preceding the diagnosis by many months/years. Survival is excellent. Historically, patients were treated according to classical HL protocols. Due to high toxicity and excellent prognosis, management of NLPHL shifted to de-escalation protocol with good results. No treatment beyond surgical resection was proposed for localized unique nodal disease completely resected. The closed European protocol (EuroNet PHL LP1) evaluated the efficacy of low intensity chemotherapy protocol based on CVP courses (cyclophosphamide vinblastine prednisone) for stage IA/IIA not fully resected. Final results are not yet available. Advanced stage NLPHL are rare and there is no clinical trial and no consensus treatment in children. The SFCE lymphoma committee recently established recommendations for staging and treatment of limited and advanced NLPHL in children based on current practices and published results. The goal was to allow homogeneous practice on a national scale. If incomplete resection for patients with stage I/IIA combination of low intensity chemotherapy (CVP) and rituximab is recommended. For intermediary and advanced stage intensification with AVD (adriamycine vinblastine dacarbazine) or CHOP courses (cyclophosphamide doxorubicine vincristine prednisone) combined with rituximab are advocated. In children, there is no indication for first-line local treatment with radiotherapy.

EBV-positive nodular lymphocyte predominant Hodgkin lymphoma: a single institution experience

The objective of this study is to characterize the clinicopathologic features of Epstein-Barr virus (EBV)-positive nodular lymphocyte predominant Hodgkin lymphoma (NLPHL) at a single institution. A retrospective review of cases diagnosed with EBV-positive NLPHL was performed and the patients' demographic and pathologic features were collected by chart review. In this study, we identified 17 EBV-positive NLPHL patients whose clinicopathologic features are characterized. EBV was positive in lymphocyte predominant (LP) cells in 6 of 17 cases, whereas the remaining cases showed EBV positivity in background small cells. Immunohistochemical analysis showed that LP cells were positive for CD20 (94.1%) in most cases and positive for OCT2 (100%) in all cases with one case showing weak OCT2 expression, whereas PAX5 and CD79a were weak and/or variable in 9 of 12 and 3 of 7 cases, respectively. CD30 was positive in 7 of 17 cases with 5 cases showing only scattered positive cells. In addition, we report a patient who had a history of EBV-negative NLPHL and showed EBV-positive NLPHL at the time of recurrence. Molecular studies performed on the 2 biopsies in the patient indicated EBV infection involving the NF-kB pathway. Our study shows that EBV-positive NLPHL is rare and may be diagnostically challenging because of atypical immunophenotypic features, such as partial expression of CD30, and weak/variable PAX5 and/or CD79a expression. The overall retention of the B-cell phenotype with strong and diffuse expression of CD20 and OCT2 in LP cells supports the diagnosis of EBV-positive NLPHL.

A high number of IgG4-positive plasma cells rules out nodular lymphocyte predominant Hodgkin lymphoma

Nodular lymphocyte predominant Hodgkin lymphoma (NLPHL) is a subtype of Hodgkin lymphoma that frequently shows a nodal growth pattern with abundant reactive B cells in the microenvironment. Early NLPHL cases can be particularly difficult to differentiate from progressively transformed germinal centers (PTGC). Since PTGC have been described to be IgG4 associated in a relatively high proportion of cases, the aim of the present study was to determine if IgG4 immunostaining can be helpful in the differential diagnosis between NLPHL and PTGC. We furthermore aimed to learn if LP cells can express IgG4. For this purpose, 58 cases of PTGC and 56 cases of NLPHL were assessed using IgG4 immunostaining. We could confirm that a significant number of PTGC cases showed high numbers of IgG4-positive plasma cells (22/58, 38%), whereas hot spot areas of IgG4-positive plasma cells were not found in any of the NLPHL cases. In lymph node areas with the differential diagnosis of NLPHL and PTGC, IgG4 immunostaining can therefore provide a helpful diagnostic tool to rule out NLPHL when a high number of IgG4-positive plasma cells are encountered. We also assessed 13 cases with a combination of NLPHL and PTGC in the same lymph node. Five of these cases presented hot spot areas of IgG4-positive plasma cells in the PTGC regions, while no significant numbers of IgG4-positive plasma cells were observed in the NLPHL part of the lymph node. LP cells were never IgG4 positive. Furthermore, immunoglobulin heavy chain rearrangements of single IgG4-positive plasma cells were analyzed, revealing a polyclonal plasma cell population. In summary, our data suggest that IgG4 immunostaining can provide additional information in the diagnostic workup of cases with the differential diagnosis of NLPHL and PTGC. IgG4's inefficiency in clearing antigens may explain why lymph nodes with PTGC are usually strongly enlarged and develop a high number of hyperplastic germinal centers. Polyclonal immunoglobulin heavy chain rearrangements in IgG4-positive plasma cells further support the hypothesis that PTGC represent a misled immune reaction.

J chain and myocyte enhancer factor 2B are useful in differentiating classical Hodgkin lymphoma from nodular lymphocyte predominant Hodgkin lymphoma and primary mediastinal large B-cell lymphoma

Although most classical Hodgkin lymphomas (CHLs) are easily distinguished from nodular lymphocyte predominant Hodgkin lymphoma (NLPHL) and primary mediastinal large B-cell lymphoma (PMBL), cases with significant CD20 expression cause diagnostic confusion. Although the absence of OCT-2 and BOB.1 are useful in these circumstances, a variable proportion of CHLs are positive for these antigens. We investigated the utility of J chain and myocyte enhancer factor 2B (MEF2B) in the diagnosis of CHL; NLPHL; PMBL; T-cell/histiocyte-rich large B-cell lymphoma (TCRLBL); and B-cell lymphoma, unclassifiable, with features intermediate between diffuse large B-cell lymphoma and CHL, compared with OCT-2 and BOB.1. J chain and MEF2B highlighted lymphocyte predominant (LP) cells in 20/20 (100%) NLPHLs and were negative in 43/43 (100%) CHLs. Fourteen of 15 (93%) PMBLs and 4/4 (100%) TCRLBLs were MEF2B positive, whereas 67% of PMBLs and 50% of TCRLBLs were J chain positive. Three of 3 B-cell lymphomas, unclassifiable, with features intermediate between diffuse large B-cell lymphoma and CHL, were negative for J chain and MEF2B. J chain and MEF2B were 100% sensitive and specific for NLPHL versus CHL. MEF2B was 100% sensitive and 98% specific for PMBL versus CHL. Whereas loss of OCT-2 and/or BOB.1 expression had a sensitivity of only 86% and specificity of 100% for CHL versus NLPHL, PMBL, and TCRLBL, lack of both J chain and MEF2B expression was 100% sensitive and 97% specific. J chain and MEF2B are highly sensitive and specific markers of NLPHL versus CHL; are particularly useful in highlighting LP cells; and, with rare exception, are of greater utility than OCT-2 and BOB.1 in differentiating CHL from NLPHL and other large B-cell lymphomas.

A 20-year population-based study on the epidemiology, clinical features, treatment, and outcome of nodular lymphocyte predominant Hodgkin lymphoma

Nodular lymphocyte predominant Hodgkin lymphoma (NLPHL) is a subtype of Hodgkin lymphoma characterized by a unique clinical and histological presentation. Because of the rare nature of this disease, few large-scale studies are available. We conducted a cohort study in which patients were identified in the Netherlands Cancer Registry in the Southeast of the Netherlands between 1990 and 2010. Of these patients, we collected all clinical characteristics and re-reviewed pathologic material to confirm NLPHL diagnosis. Seventy-three histologically confirmed cases of NLPHL were analyzed with a median follow-up of 65 months (range 4–257 months). Median age at diagnosis was 43 years (range 1–87); 84.9 % of the patients were male; B symptoms were present in 5.5 %; and stage I/II disease was most common (75.4 %). Patients were primarily treated with radiotherapy (50.7 %), chemotherapy (26 %), combined modality (radiotherapy and chemotherapy) (11 %), or surgical excision with careful watch-and-wait (12.3 %). Relapses occurred in seven patients (9.6 %) after a median of 26 months (21–74 months). Six patients (8.2 %) developed histologic transformation to large cell lymphoma. Five patients (6.8 %) died during follow-up due to progression of NLPHL (n = 1), histologic transformation (n = 2) and intercurrent deaths (n = 2). The estimated 10-year overall survival was 94.0 % and the 10-year progression-free survival 75.8 %. Our study confirms the distinct characteristics of NLPHL with a relatively good long-term prognosis. It may be possible to reduce treatment intensity in early stage NLPHL without affecting long-term outcome.

A simplified scoring system to document variant patterns in nodular lymphocyte predominant Hodgkin lymphoma

This study sought to quantify variant patterns in nodular lymphocyte predominant Hodgkin lymphoma (NLPHL) using a three tier scoring system assessing five parameters, namely: (a) percentage of nodularity scored from 100 % to < 75%, (b) T cell rich areas (< 20% to > 50%), (c) type of nodules, (d) dendritic network, intact or lost, and (e) extranodular distribution of lymphocyte predominant cells (< 15% to > 50%), with final scores from 0 to 10. In the 72 patients assessed, the 5-year disease-free survival (DFS) in patients with score ≤ 6 was 92% vs. 20% in those with scores > 6. The 5-year overall survival was 100% in patients with scores ≤ 6 and 87% in those with scores > 6. In the multivariate Cox regression analysis, scores > 6 and stage impacted DFS. This scoring system was effective in stratifying patients with NLPHL with variant patterns and could be used for the management of patients.

Epstein-Barr virus-positive nodular lymphocyte predominant Hodgkin lymphoma

Hodgkin lymphoma (HL) is classified into 2 largely distinct subgroups, namely nodular lymphocyte predominant HL (NLPHL) and classic HL (CHL). CHL is further divided into nodular sclerosis, lymphocyte-rich, mixed cellularity (MCCHL) and lymphocyte-depleted (LDCHL) subtypes. In industrialized nations, Epstein-Barr virus (EBV) has been associated with all types of CHL, especially the MCCHL and LDCHL subtypes, but is rare in NLPHL. We report 8 cases of EBV-positive NLPHL occurring in patients in the United States. All 8 patients have no history of immunosuppression and presented with localized or systemic lymphadenopathy. Histologically, 6 cases had a vaguely nodular pattern and 2 cases had a nodular and diffuse pattern. In all cases, lymphocyte predominant (LP) cells were observed in a background of small lymphocytes and histiocytes. Immunohistochemical analysis showed that the LP cells in all cases were positive for CD20, CD79a, PAX5, OCT2, and CD45 and were negative for CD15. CD30 was expressed variably in 7 cases. EBV encoded RNA was present in all LP cells in 5 cases and in a subset of LP cells in 3 cases. One patient was treated with radiation therapy and 7 patients received chemotherapy, including 4 of 7 patients who underwent autologous stem cell transplantation. EBV infection is a rare primary or secondary event in NLPHL that correlates with poorer prognosis and often requires more aggressive therapy. The variable expression of CD30 in most of these cases could be the result of EBV infection.

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.