Primary cutaneous leiomyosarcoma: a clinicopathological and immunohistochemical study of 7 cases.

Primary cutaneous leiomyosarcomas are rare tumors, few series being reported in the current literature. A retrospective study of 7 cases was undertaken to understand the clinicopathological characteristics of these neoplasms and some of their molecular mutations. Histologically, a well-differentiated proliferation of cells of smooth muscle derivation was evident in all cases. The number of mitoses was considered the most important criterion of malignancy (more than 2 for 10 HPF). Smooth muscle actin, desmin, and vimentin were positive in all cases. Immunohistochemical analysis also revealed a positivity for p53 in 3 cases and no reaction for retinoblastoma protein. Research for Epstein-Barr virus was negative in all cases. Three patients developed local recurrences owing to incomplete surgical excision. Recurrent tumors were more atypical and located deeper. No distant metastases were observed. Our results emphasize that cutaneous leiomyosarcomas have an indolent biological course if treated by surgical excision with wide margins. Molecular abnormalities involving tumor suppressor genes are probably involved.