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Case ReportsAbstract
Kaposi sarcoma (KS) is a vascular neoplasm caused by human herpesvirus 8, most commonly involving the skin, mucosa, and visceral organs. While the classic histological findings of spindle cells intermixed with slit-like vascular channels are well known, a review of the literature reveals only a few papers addressing the rare variant with epithelioid morphology. We report a 30-year-old man with newly diagnosed HIV-1 infection (CD4 count of 167 cells/mm3) who presented with worsening malaise, myalgia, intermittent abdominal and back pain, and painful lymphadenopathy in the neck, axillary, and pelvic regions. Dermatologic examination revealed scattered red-to-violaceous smooth papules on the face and chest as well as involvement of the hard palate. The clinical differential included KS as well as other infectious processes, such as bacillary angiomatosis. A punch biopsy was performed on a lesion from the chest, and H&E slides demonstrated a dermal proliferation of epithelioid-shaped cells arranged in cords and aggregates dissecting collagenous bundles. The surrounding stroma showed fibroplasia with cleft-like spaces, extravasated erythrocytes, and focally admixed spindle-shaped cells. Immunohistochemical staining for HHV8 was positive in the epithelioid and spindle shaped cells, confirming the diagnosis of KS. This case highlights the importance of considering KS in the differential diagnosis—even when the classic spindle cell morphology is not conspicuous—in at risk populations. Moreover, it underscores the role of immunohistochemistry in establishing the correct diagnosis.