HIV‐negative HHV8‐positive multicentric Castleman's disease coexistent with atypical Kaposi's sarcoma

The co‐occurence of multicentric Castleman's disease (MCD) and Kaposi's sarcoma (KS) represents a rare clinical entity, mostly observed in individuals infected with the human immunodeficiency virus (HIV). Human herpesvirus 8 (HHV‐8) is attributed a crucial etiological role in both conditions. This study presents the case of a 75‐year‐old woman who manifested an angiomatous lesion on the right thigh and erythematous firm plaques on the trunk and limbs, accompanied by asthenia, weight loss, and recurrent febrile episodes. Serological markers for HIV yielded negative results. Contrast‐enhanced computed tomography (CT) and fluorine‐18 fluorodeoxyglucose positron emission tomography (18 F FDG PET/CT) revealed multiple enlarged and intensely hypermetabolic lymph nodes in the supraclavicular, cervical, thoracic, and abdominopelvic regions. Subsequent excisional biopsy and immunohistochemical analysis confirmed the diagnosis of HIV‐negative HHV8‐positive MCD coexisting with KS.