Abstract
A 49-year-old woman, who had undergone hysterectomy for low-grade endometrial stromal sarcoma (ESS) 3 years ago, presented with a 2-wk history of lower abdominal pain. Barium enema and sigmoidoscopy disclosed a polypoid submucosal tumor. Histopathologic features of biopsy specimens from the lesion were similar to those of the resected uterine ESS. Under the diagnosis of metastatic ESS of the sigmoid colon, sigmoidectomy was performed. Microscopic examination demonstrated dense proliferation of spindle cells with little nuclear atypia, which were sometimes arranged in whorled pattern around abundant arterioles. Mitotic count is below 1 in 10 high-power fields. Immunohistochemically, the neoplastic cells were strongly positive for vimentin, estrogen receptor and progesterone receptor but negative for alpha-smooth muscle actin, S-100 protein and CD34. Thus, a final diagnosis of low-grade ESS metastasis to the sigmoid colon was made. Her postoperative course was uneventful and hormonal therapy with progestational agents is entertained.