Endometrial Stromal Sarcoma Arising from Endometriosis

The malignant transformation of endometriosis is a very uncommon event but can occur in 0.7% to 1% of all cases. Any histological type of tumor found in the endometrium might also occur in endometriosis. Most malignant tumors that originate from endometriosis are endometrioid adenocarcinomas and also clear-cell type carcinomas. On the other hand, sarcomas, especially endometrial stromal sarcoma (ESS), are extremely unusual representing 12% of all cases. ESS is an uncommon neoplasm and accounts for 0.2% of the uterine malignances. Malignant tumors arising from endometriosis can derive from the uterine wall as well as from extra-uterine sites. The most frequent extrauterine location is the ovary (78.7%), followed by the pelvic peritoneum (5.7%), the rectovaginal septum (4.3%), the colon (4.3%) and the vagina (2%), representing the majority of extragonadal sites. ESSs arising from the extrauterine and extraovarian endometriosis sites in the absence of a primary uterine lesion are extremely rare and the treatment options are not clear. Surgical debulking seems to be the best treatment. Adjuvant therapy, such as radiation, hormonal therapy and chemotherapy are not yet proven to be effective. Molecular target therapy could be a future possibility of treatment.

A systematic review of English Medical Literature about incidence, treatment and prognosis of extrauterine ESS arising from endometriosis foci was performed. The selected articles on which this review is based are the following: 9 literature reviews, 8 retrospective studies, 7 case series, 1 prospective trial and 11 case reports.