Endometrial stromal sarcoma presenting as an ovarian cyst – A case report

Introduction: Endometrial stromal sarcomas usually arise in the uterine corpus while it is rare in extra-uterine sites. The most common extra-uterine site is the ovary. However, primary endometrial stromal sarcoma of the ovary rarely arises in a serous tumor. We report a case of primary ovarian ESS presenting in the wall of a serous cyst along with a synchronous endometrial stromal nodule (ESN). Case report: A 50 year old woman presented with lower abdominal pain and fullness. On radiological examination, a left ovarian, predominantly cystic mass about 10cm in diameter was found along with an uterine nodule, 1.5cm in diameter, presumed to be a leiomyoma. The ovarian cyst on histology was diagnosed as ESS arising in a serous cystadenoma. The uterine nodule was diagnosed as ESN since there was no myometrial or vascular invasion. Discussion: Endometrial stromal sarcomas pose a diagnostic challenge at extra-uterine sites. Malignant mixed mullerian tumor and sex cord stromal tumor are close differential diagnoses. The other problem is deciding whether the tumor is primary or secondary. The problem of diagnosis is compounded if the presentation is cystic. Conclusion: We concluded that primary ovarian ESS should be diagnosed after excluding possible metastatic spread from uterine ESS. In cases with an uterine nodule, the periphery of the lesion should be thoroughly sampled to exclude ESS. We also suggest that an ovarian cyst is not necessarily epithelial. Key-words: endometrial stromal sarcoma, endometrial stromal nodule, cyst School of Tropical Medicine, Kolkata, West Bengal, India; Nil Ratan Sircar Medical College, Kolkata, West Bengal, India ______________________________________________________________________