Abstract

A 44-year-old woman underwent the diagnosis of adenomyosis uteri, and the left adnexal mass was found at the time of operation. The tumor tissue mainly formed solid, partly cystic masses which was spread to the omentum, peritoneum and mesentery. The tumor was diagnosed as extrauterine endometrial stromal sarcoma without preexisting endometriosis. Distinctive histologic features identifying this neoplasm as ectopic growths of endometrial stroma included prominent vessels, focal stromal foam cells, bland cytologic features and rare mitoses. The uterine endometrium and the myometrium were entirely free from any neoplastic growth or hyperplastic change. The perimetrial surface showed several scattered nodular involvement of tumor spread. However, no myometrial invasion was found.