Disseminated Kaposi sarcoma with epithelioid morphology in an HIV/AIDS patient: A previously unreported variant

Kaposi sarcoma is an oligoclonal HHV-8-driven vascular proliferation that was first described by a Viennese dermatologist Dr Moritz Kaposi. The disease has been seen in different clinical-epidemiological settings with a wide morphologic spectrum. We report a 52-year-old Caucasian man with HIV/AIDS and Kaposi sarcoma who presented with dyspnea and pleural effusion. He reported numerous tender subcutaneous nodules developing over the past few months on his chest, back and abdomen. An excisional biopsy of one of the nodules was performed. Touch preps revealed malignant cells in clusters. Microscopically, the neoplasm appeared undifferentiated with an epithelioid morphology, and involved the dermis and subcutaneous fat. Despite the medical history, Kaposi sarcoma was not considered foremost in the differential diagnosis. The malignant cells were positive for vimentin and negative for S100 protein, keratin AE1/3, CK7, CK20, napsin A, TTF-1 and synaptophysin. Additional stains revealed positivity for HHV-8, CD31 and D2-40, supporting the diagnosis of Kaposi sarcoma. Kaposi sarcoma has been well described with many variants that may cause diagnostic difficulty. An epithelioid variant has not been reported and consequently, may cause misinterpretation of an otherwise well-known entity that may become life threatening if appropriate treatment is not initiated in a timely manner.