Leiomyosarcoma of the Anus

Abstract

Six cases of leiomyosarcoma arising in the anus were analyzed both clinicopathologi cally and immunohistochemically. All patients were women, and the mean age was 57 years. The tumors were classified according to the predominant histologic features: two were well and four were moderately differentiated. No poorly differentiated or dedifferentiated areas were recognized. Epithelioid features were seen in parts of all cases. The number of mitoses per 10 high-power fields (HPF) ( x 400) were 1 and 2 in one case each and 4-9 in four cases. Immunohistochemically, all the tumors were positive for muscle-specific actin (HHF35). Alpha smooth muscle actin and desmin were positive in three and four cases, respectively. Two of the six cases died of the disease. Three of the four cases with high mitotic figures (four or more per 10 HPF) either died of the disease or had a local recurrence. These findings suggest that many anal leiomyosarcomas may immunohistochemically and histologically belong to the differentiated type, while the mitotic rate may be an important prognostic factor. Int J Surg Pathol 1(4):221-226, 1994