Coexistence of HHV-8-Associated Plasmacytic Multicentric Castleman Disease, Kaposi's Sarcoma, and Multiple Myeloma in a HIV-Negative Patient.

Background: Multicentric Castleman disease (MCD) is a rare, aggressive lymphoproliferative disorder. Human herpesvirus-8 (HHV-8) has an important role in the pathogenesis of the disease and its association with Kaposi's sarcoma has been reported, especially in people living with human immunodeficiency virus (HIV). In this report, we present the case of HHV-8 positive MCD accompanied by Kaposi's sarcoma and multiple myeloma in an HIV-negative patient. Case Report: A 78-year-old man with Kaposi's sarcoma presented with B symptoms, pancytopenia, lymphadenopathy, and splenomegaly. The bone marrow biopsy demonstrated 70% lambda-restricted monotypic plasma cell infiltration consistent with plasma dyscrasia. Also, the patient was diagnosed with HHV-8 positive MCD as a result of inguinal lymph node excisional biopsy. Treatment was initiated including ganciclovir and methylprednisolone and followed by rituximab. The patient passed away at the 24th hour of rituximab infusion due to shock. Conclusions: MCD and associated malignancies are difficult to treat and have a poor prognosis. More studies and data are needed to manage these patients. LEARNING POINTS: Multicentric Castleman disease (MCD), often linked with human herpesvirus-8 (HHV-8) and Kaposi's sarcoma, is rare and aggressive condition, particularly in human immunodeficiency virus (HIV)-positive patients.The coexistence of MCD, Kaposi's sarcoma, and multiple myeloma is exceptionally rare in HIV-negative, immunocompetent patient.This case highlights the challenges in diagnosing and managing complex presentations of MCD and related malignancies, with poor outcomes despite treatment.