Hodgkin Lymphoma: Nodular Lymphocyte Predominant Subtype V.s. Lymphocyte-Rich Classic Subtype, A Clinicopathological, Immunophenotypical Comparing Study And The Clonal Correlations Among The L & H Cells From Distinct Nodules

[Background and Objective] Nodular lymphocyte predominant Hodgkin lymphoma (NLPHL) and lymphocyte-rich classic Hodgkin lymphoma (LRCHL) are distinct entities with different immunophenotypes and clinical features, but histopathologically sometimes it is difficult to distinguish between them. It has been reported that the B-cell transcription factors, B-cell-specific activator protein (BSAP), B-cell oct-binding protein 1 (BOB.l), and octamer-bingding transcription factor 2 (Oct-2), are useful in the differentiated diagnosis of NLPHL and LRCHL. In the present study, 28 patients of NLPHL and 25 patients of LRCHL were analyzed retrospectively in the aspects of clinical manifestations, histopathology, immunophenotyping, and the association with Esptein-Barr virus infection, in order to evaluate the roles of B-cell transcription factors and other markers in the differentiated diagnosis between NLPHL and LRCHL. In this study the B-cell clonalities of L&H cells from distinct nodules of one case of NLPHL were also analyzed by microdissection and PCR methods in order to estimate whether they origin from a same B-cell clone.[Materials and Methods] 28 cases of NLPHL and 25 cases of LRCHL were selected from the surgical pathologic files of Department of Pathology, West China Hospital, Sichuan University between 1996 and 2007. In addition to histopathological observation, all available paraffin embedded specimens were stained for LCA, CD20, CD30, CD15, CD57, CD79α, EMA, BSAP, BOB.1, Oct-2, CD3ε, CD45RO, CD10, and bcl-6. The infective condition of EBV was detected by in situ hybridization using pepted nucleic acid probe to EBER1/2 RNA. Techniques of laser microdissection, PCR, and sequencing were also used to evaluate the clonal correlation of L&H cells from two distinct nodules of one case of NLPHL.[Result] (1) Histopathological features: Of the 28 patients with NLPHL, 23 (82.1%) showed a purely nodular growth pattern, whereas 5 (17.9%) presented a nodular and diffuse growth pattern. Residual germinal center and PTGC were only observed in one case, respectively. L&H cell (popcorn cell) was found in all cases of NLPHL. There was no patient developed DLBCL, either synchronously or metachronously. Of the 25 patients with LRCHL, there were 15 (60.0%) with a purely diffuse growth pattern, 6 (24.0%) with a nodular and diffuse growth pattern, and 4 (16.0%) with a purely nodular growth pattern. Residual germinal center could be observed in 9 cases (36.0%). H/R-S cell was found in all LRCHL cases. (2) Immunophenotyping and EBV infection: The positive reactions of L & H cells in the cases of NLPHL were observed as follows: LCA 18/18 (100%), CD20 24/25 (96.0%), CD30 4/24 (16.7%), CD15 0/24 (0%), CD79a 18/21 (85.7%), EMA 10/21 (47.6%), and bcl-6 9/19 (47.4%), respectively. The expressions of three B-cell transcription factors, BSAP, BOB.l, and Oct-2, were found in L&H cells of all available cases of NLPHL (21/21, 100%), respectively. The phenomena of CD57 positive lymphocyte rosette around the L&H cells was observed in 10 of 21 NLPHL cases (47.6%). There was only one case of NLPHL in which EBER positive L&H cells were found (4.8%). The immunohistochemical reactions of H/R-S cells in the cases of LRCHL were presented as follows: LCA 0/14 (0%), CD20 6/17 (35.3%), CD30 18/18 (100%), CD15 10/18 (55.6%), CD79α3/15 (20.0%), EMA 0/15 (0%), and bcl-6 0/14 (0%), respectively. The expressions of BSAP, BOB.l, and Oct-2 were observed in 13/14 (92.9%), 2/14 (14.3%) and 12/14 (85.7%), respectively. Positive expression of EBER in the H/R-S cells was found in 11 of 14 LRCHL cases (78.6%). There was no case with CD57 positive lymphocyte rosette around H/R-S cells. (3) Clinical manifestations: the numbers of NLPHL and LRCHL accounted for 3.5% (28/798) and 3.1% (25/798) of all Hodgkin lymphoma in the period between 1996 and 2007, respectively. The mean age of the patients with NLPHL was 37 years, whereas 33 years of the patients with LRCHL. The ratio of male to female of the patients with NLPHL was 2.5:1, whereas 4:1 for the patients with LRCHL. In both groups the most common involved site was cervical lymph node (75.0% v.s. 84.0%). 16 of 20 patients (80.0%) with NLPHL were classified as stageⅠ-Ⅱ, whereas 10 of 14 patients (71.4%) with LRCHL were identified stageⅠ-Ⅱaccording to Ann Arbor staging system. The overall five year survival rate of patients with NLPHL was a little better than those patients with LRCHL (81.4% v.s. 57.1%), but there was no statistic significance. (4) Clonality correlation: Clonal IgH gene rearrangement was detected by using laser microdissection and PCR methods in L&H cells from two different nodules in one case of NLPHL. Sequencing result showed that the rearranged IgH gene segments came from different J and D region.[Conclusions] (1) Nodular growth pattern in NLPHL is more frequent than in LRCHL. (2) The helpful immunohistochemical markers in favor of NLPHL are LCA+ CD20+ CD30-CD15-CD79α+ EMA+ BOB.1+ bcl-6+ EBER-, whereas those in favor of LRCHL are LCA-CD20-/+ CD30+ CD15+ CD79α-/+ EMA-BOB.1-bcl-6-EBER+. CD57 positive lymphocyte rosette is also an effective marker. Our results does not support that Oct-2 is a useful marker in the differentiated diagnosis between NLPHL and LRCHL. (3) The L&H cells from different nodules of NLPHL could origin from distinct B-cell clone.