Lymphocyte predominance Hodgkin's disease - The use of bcl-6 and CD57 in diagnosis and differential diagnosis

Distinction of lymphocyte predominance Hodgkin's disease (LPHD) from other forms of lymphoma often requires immunohistochemistry (IHC). Most previousl y published recommended panels include markers to define the large neoplast ic cells (for example, CD20, J chain, CD45) as well as the nonneoplastic ba ckground cells (CD21, CD35RO, CD57, TiA1). In the present study we examine the practical use of a double LHC method designed to look simultaneously at two germinal center specific cell types: bcl6+ cells and [bcl6+, CD57+] co -positive cells. All 10 nodular LPHD had bcl6+ large cells and numerous CD5 7+ small background cells, including [bcl6+CD57+] cells in rosettes. One ca se of LPHD with large cell transformation contained numerous bcl6+ large ce lls both singly (in areas of typical LPHD) and in sheets (in foci of large cell transformation), many CD57+ small cells but few [bcl6+CD57+] co-positi ve cells and no rosettes. In none of the five cases of florid progressive t ransformation of germinal centers were true rosettes seen, although all con tained variable numbers of bcl6+ large cells and CD57+ cells. Lymphocyte-ri ch classic Hodgkin's disease LRCHD cases were notable for bcl6 reactivity i n Reed-Sternberg cells in all cases, numerous background small bcl6+ lympho cytes, and rare CD57+ cells. Two phenotypic profiles were associated with t he 10 cases of T cell-rich B cell large cell lymphoma (TCRBCL). In the firs t, group "A," six of six cases had bcl6+ large cells and few CD57+ small ce lls, and none had significant numbers of [bcl6+, CD57+] co-positive cells. In the second, group "B," four of four cases had bcl6+ large cells with num erous CD57+ and [bcl6+, CD57+] co-positive cells. These findings not only s how that LPHD can be distinguished from its morphologic mimics through iden tification of specific germinal center cell types, but also identifies a se cond group of TCRBCL (group "B") whose phenotype suggests it might be an ar chitectural variant of nodular LPHD.