Cutaneous leiomyosarcoma of the scalp

Clear-cell variant of superficial cutaneous leiomyosarcoma associated with RB1 mutation: Clinical, dermoscopic, and histopathological characteristics

Leiomyosarcoma is a relatively rare soft tissue tumor whose clear-cell variant has only been reported in leiomyosarcomas of the uterus. We report here for the first time a primary cutaneous clear-cell leiomyosarcoma in the trunk skin of a 49-year-old man, characterized by a very indolent clinical and dermoscopic presentation, mimicking a dermatofibroma. Genetic analysis of the otherwise healthy patient revealed a germline mutation in the retinoblastoma 1 gene (RB1); the same mutation was found in his son, who had previously developed retinoblastoma. Moreover, the mother of the patient had died of uterine leiomyosarcoma with clear-cell changes. Mutations in the RB1 gene occur commonly in human neoplasms. In this patient, we were able to link his clear-cell variant of cutaneous leiomyosarcoma with the loss of retinoblastoma protein expression, as revealed by immunohistochemical staining analysis.

Cutaneous leiomyosarcoma on the face

Leiomyosarcoma is a rare skin tumor, most common in white men in the fifth to eighth decades of life. Primary tumors are classified in dermal or subcutaneous, that differ by clinical and prognostic features. They may appear on any site of the body, but are rare on the face. A 54-year-old female was admitted with a 5cm exophytic nodular lesion of 8 months duration on the right cheek, site of previous chronic radiodermatitis. Histopathology revealed spindle-shaped cell neoplasia, positive for smooth muscle actin on immunohistochemistry. Cutaneous leiomyosarcomas on the face are rare and may occur in previously irradiated areas. Immunohistochemistry is mandatory for an accurate diagnosis. Its similarity with other tumors may complicate the diagnosis, with delay expansion of the tumor.