Abstract

Epithelioid smooth muscle tumor is relatively rare and potentially malignant, especially in retroperitoneum. Distinct criteria for malignancy still have not been clarified in this epithelioid variant arising in retroperitoneum. We report a deceptively benign-appearing epithelioid leiomyosarcoma in a 50-year-old female. She was admitted with abdominal discomfort and dysuria. Abdominal CT showed a well-demarcated, 10 10 cm sized, solid mass in retroperitoneum. Concomitant metastatic lesions were noted in right lung field. Surgical excision of retroperitoneal mass and right lung lobectomy were performed. The retroperitoneal mass showed yellowish-tan, well-delineated and lobulated appearance. Histologically, this tumor was composed of predominantly epithelioid, round to oval cells with distinct clear cytoplasm and slightly atypical nuclei. Mitosis was rare (0~1/50 HPF). Lung lesions were morphologically similar to that of retroperitoneum.

• Keywords: Epithelioid leiomyosarcoma;Retroperitoneum