Rare variants in the spectrum of human herpesvirus 8/Epstein-Barr virus-copositive lymphoproliferations.

We report 2 rare variants in the spectrum of human herpesvirus 8 (HHV8)/Epstein-Barr virus (EBV)-copositive lymphoproliferations arising in HIV-seronegative patients, including a large B-cell lymphoma arising in the setting of multicentric Castleman disease and a germinotropic lymphoproliferative disorder. In the first case, histology revealed features of multicentric Castleman disease and a proliferation of large lymphoid cells forming clusters or arcs or rings replacing the periphery of follicles or sheets of frank lymphoma outside the follicles. In the second case, a proliferation of large lymphoid cells totally or partially invaded follicle germinal centers. In both cases, the large cells were positive for EBV-encoded small RNA, HHV8 (LANA-1), MUM1/IRF4, and CD38 and negative for CD45, CD79a, CD10, BCL6, and CD138. In the large B-cell lymphoma, the large cells did not express detectable cytoplasmic immunoglobulin light- and heavy-chains, whereas in the germinotropic lymphoproliferative disorder, the large cells expressed μ heavy chain. The present cases broaden the spectrum of HHV-EBV--copositive lymphoproliferations.