Cystic endometrial stromal sarcoma mimicking a cystic ovarian tumor : an unusual presentation

Abstract Low grade endometrial stromal sarcoma (LGESS) typically presents as a solid intracavitary or intramural uterine mass. On imaging, LGESS is usually seen as an endometrial or myometrial solid mass. Cystic change is unusal and may lead to a differential diagnosis of an ovarian mass as was seen in the present case. Here we present a case of a 38 year old woman who presented with a cystic ovarian mass clinically and radiologically. Per-operatively, it was found to be a multiloculated cystic mass, filled with serosanguinous fluid, in the uterine fundus. Histopathological examination showed a tumor mass composed of mainly spindle cells arranged in fascicular pattern showing marked myxoid degeneration and cystic areas. On immunohistochemistry(IHC), tumor cells showed positivity for CD 10, ER, PR, SMA and desmin while HMB45 was negative. Based on histopathological and IHC, a diagnosis of LGESS was made. Most cases of cystic uterine masses have a benign course but, LGESS exhibits a relatively poorer outcome and a risk of metastasis. Hence, we present this case for its unusual presentation which mimics an ovarian mass but has worse prognosis.