Cutaneous Horn-Related Kaposi's Sarcoma: A Case Report.

Cutaneous horn is characterized by the accumulation of abnormal keratinized material and may occur in association with a variety of benign, premalignant, and malignant cutaneous lesions. Cutaneous horn occurs very rarely in association with soft-tissue neoplasias. A cutaneous horn located on the toe was completely removed by excision in a 78-year-old male patient. Macroscopic examination revealed a hemorrhagic nodular lesion, 0.5 cm in diameter, located on the dermis underlying the cutaneous horn with a height of 1 cm. Histopathological examination revealed a neoplastic lesion consisting of fusiform cells and extravasated erythrocytes underlying the compact keratin mass. The immunohistochemical analysis showed immunoexpression of endothelial markers and HHV8 in fusiform cells. The case was evaluated as "cutaneous horn developed in a nodular stage Kaposi's sarcoma." Our case is the second case of cutaneous horn related to Kaposi's sarcoma reported in the English literature and is presented in this case report with its clinical and histopathological features.