Paratesticular pleomorphic rhabdomyosarcoma in the elderly. An immunohistochemical, ultrastructural study and review of the literature

A case of paratesticular pleomorphic rhabdomyosarcoma, presenting as an ulcerated mass in the left hemiscrotum of an 83-year-old man, is reported. By light microscopy, this neoplasm could not be distinguished from other pleomorphic sarcomas, such as malignant fibrous histiocytoma, leiomyosarcoma, and liposarcoma. Immunohistochemistry showed that most tumor cells were strongly reactive with antibodies directed against myoglobin, desmin, α- sarcomeric actin, and myogenin, whereas α-smooth muscle actin expression was less extensive. Electron microscopic examination demonstrated thick and thin filaments with condensations of electron-dense material reminiscent of structures of Z-lines in the large pleomorphic cells. On the basis of these findings, the neoplasm was classified as a pleomorphic rhabdomyosarcoma. According to a review of the literature, this is the first well-documented example of paratesticular pleomorphic rhabdomyosarcoma in an elderly person.