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A Case Report of Primary Leiomyosarcoma of the Skin

Primary leiomyosarcoma of the skin is a rare tumor. It is more prevalent in men, and always is seen in the extremity extensor surface especially the thighs and around knee and head and neck region, with greater incidence in fifth to seventh decades of life. Leiomyosarcoma is localized to the skin in two sites: cutaneous and subcutaneous. Subcutaneous leiomyosarcoma with vessel wallʹs smooth muscle origin has a distinctive pattern, so may be misdiagnosed as a vascular tumor. Light and electron microscopy and immunohistochemistry can easily do diagnosis. Prognosis of cutaneous leiomyosarcoma is much better than the subcutaneous type, which has 30-60% rate of metastasis that can be determined by flowcytometric methods. In this case, we report an 80-year-old woman with a cutaneous nodular lesion on the right thigh. On macroscopic examination, the tumor had 1.8-centimeter diameter and 1.5cm depth, and in microscopy, cutaneous leiomyosarcoma with prominent cellular atypia was diagnosed. Specific staining confirmed the diagnosis. The tumor was excised widely, to prevent of recurrence.