MTX-CHL was more frequently the mixed cellularity subtype and positive for Epstein-Barr virus, but less frequently positive for CD20 than sporadic CHL.
We observed 86 cases with a morphology more closely related to cHL, but with an LBCL immunophenotype based on strong and homogenous B-cell marker expression (CD20 and/or CD79a, OCT2, BOB1, PAX5) on all tumor cells (cHL-like GZL).
High numbers of CD21+ follicular dendritic cell networks, CD20+ B cells, IgM+ cells, CD20+ aggregates, and Bcl6+ cells were associated with a better outcome of cHL patients, whereas Pax5+/CD38+ cells had an adverse prognostic impact.
Although CD20was negative and PAX5 and CD45 were down-regulated, the pleomorphic large cells expressed multiple other B-cell antigens which are characteristically absent in cHL.
All ptHL expressed CD15, CD30 and LMP-1 of EBV; the B-cell markers BOB-1, Oct2, CD79a and CD20 were more commonly expressed in ptHL versus cHL (100%, 86%, 50% and 38% in ptHL compared to 6%, 14%, 10% and 33% in cHL, respectively); all ptHL expressed phosphoinositide 3-kinase (PI3K) versus 81% of cHL; 2/6 (33%) ptHL displayed gains at 9p24 that were similar to cHL (32%).
Immunohistochemical studies revealed that the large atypical cells were CD30 (+), CD15 (weakly +), CD20 (-), CD45 (-), Pax5 (weakly +), BOB.1 (-), and Oct2 (-), indicating the coexistence of SMZL with cHL.