Expression of B-cell markers in classical Hodgkin lymphoma: A tissue microarray analysis of 330 cases

Hodgkin and Reed-Sternberg cells of classical Hodgkin lymphoma arise from B-lymphocytes. However, classical markers of the B-cell phenotype, such as CD20, are present only in about 25% of the cases. The aim of the present study was to assess expression of the B-cell-related antigens CD20, CD79a, and CD138 hi classical Hodgkin lymphoma using a tissue microarray consisting of 330 classical Hodgkin lymphoma cases. Expression of CD15, CD20, CD30, CD79a, CD138, and latent membrane protein I of Epstein-Barr virus was assessed by immunohistochemistry, and the methodology was validated by direct comparison of CD20 expression on the tissue microarray cores with corresponding large sections. The influence of the number of arrayed sample cores on the obtained expression levels of CD20 was analyzed by comparing the results from single, duplicate, and triplicate cores. Two-hundred fifty-three (77%) of the 330 cases were morphologically representative. CD20 was expressed in 84 cases (33%), CD79a in 26 (10%), and CD138 in 2 (1%), respectively. CD20 and CD79a were co-expressed in 16 cases (P <.005), and expression of CD20 correlated inversely with CD15 (P <.01). Comparing the tissue microarray results with those from conventional sections for expression of CD20 yielded a concordance of 94% (63/67). Examining one, two, and three cores from individual cases revealed positivity for CD20 at 24% (61/ 253), 32% (82/253), and 33% (84/253), respectively. We conclude that B-cell markers are expressed in 38% of classical Hodgkin lymphoma in the following rank order: CD20>CD79a>>CD138. The use of two cores per tissue sample renders the tissue microarray technology effectively representative and thus very useful for high-throughput evaluation of heterogeneously expressed markers in classical Hodgkin lymphoma.