Concurrent Presentation of Human Herpesvirus 8-Associated Multicentric Castleman Disease and Kaposi Sarcoma in a Young Patient.

Castleman disease and Kaposi sarcoma are uncommon conditions that can occur in association with human immunodeficiency virus (HIV) infection. We report a case of a 26-year-old man newly diagnosed with acquired immune deficiency syndrome who presented with fever, nocturnal chills, generalized lymphadenopathy, hepatosplenomegaly, anemia, and thrombocytopenia. Imaging revealed widespread lymphadenopathy and bone marrow hypermetabolism. Histopathological examination of an excised cervical lymph node demonstrated atrophic follicles with involuted germinal centers and an expanded mantle zone containing scattered plasmablasts - features consistent with Kaposi sarcoma herpesvirus/human herpesvirus 8 (KSHV/HHV-8)-associated multicentric Castleman disease, with microscopic foci of Kaposi sarcoma featuring spindle cell proliferation with slit-like vascular channels. Immunohistochemical staining confirmed HHV-8 positivity in plasmablasts and spindle cells of Kaposi sarcoma. This case highlights the importance of a thorough evaluation of HIV-positive patients presenting with lymphadenopathy to ensure early recognition of rare but clinically significant conditions requiring aggressive management. Recognition of concurrent HHV-8-associated Castleman disease and Kaposi sarcoma is critical, as treatment strategies differ and outcomes may be influenced by early therapeutic intervention.