Leiomyosarcoma of the skin with generalized metastases: electron microscopic and immunohistochemical study

A 62-year-old woman with numerous (more than 50) tumors between 25 and 75 mm in diameter disseminated over most of her body surface is reported. Biopsied tissue specimens demonstrated that the tumors consisted mainly of spindle-shaped cells with nuclear pleomorphisms and relatively high mitotic rates. They were irregularly arranged; they sometimes mimicked storiform- and palisading-patterns. Immunohistochemistry revealed that the tumor cells were positive for muscle-specific actin, desmin, and myosin, but negative for S-100 protein. Electron microscopy confirmed myofilaments and dense patches in the cytoplasm. The metastatic potential of such leiomyosarcoma of the skin is indicated.