Human herpesvirus-8 (HHV-8) is associated with several distinct lymphoproliferative disorders: primary effusion lymphoma, multicentric Castleman disease (MCD), MCD-associated plasmablastic lymphoma and HHV-8+, Epstein-Barr virus (EBV)+ germinotropic lymphoproliferative disorder. We report the case of a human immunodeficiency virus (HIV)+ male with fever, generalized lymphadenopathy, and splenomegaly. Two peripheral lymph nodes were excised and showed features of MCD and a prominent proliferation of HHV-8+, EBV+, CD20−/+, CD138−, MUM1+, λ dim+, Ig heavy chain plasmablasts and immunoblasts replacing some follicles. Subsequently, a splenectomy and biopsy of retroperitoneal lymph nodes were performed; the retroperitoneal and splenic hilar lymph nodes showed changes similar to those in the peripheral lymph nodes while the markedly enlarged spleen showed replacement of occasional white pulp by the HHV-8+, EBV+ large cells. The histologic features and coinfection by EBV and HHV-8 suggested a diagnosis of HHV-8+ germinotropic lymphoproliferative disorder. However, the occurrence in an HIV+ individual, the background of MCD, the widespread anatomic distribution and the aggressive clinical course tended to exclude germinotropic lymphoproliferative disorder, and to favor multifocal plasmablastic microlymphoma. The patient died shortly after surgery; postmortem examination showed progression to overt lymphoma. The marrow showed extensive hemophagocytosis, consistent with development of a hemophagocytic syndrome. This unique case has clinical features compatible with a MCD-associated plasmablastic lymphoproliferative disorder, with pathologic features intermediate between HHV-8+ plasmablastic microlymphoma, and HHV-8+ germinotropic lymphoproliferative disorder, although in contrast to both of these, in our case, light chain expression was dim and heavy chain was not detected.