Uterine Low Grade Endometrial Stromal Sarcoma Presented as Extrauterine Masses: A Case Report

ABSTRACT

Endometrial stromal sarcoma (ESS) is a mesenchymal neoplasm that usually occurs as a primary tumor of the uterine corpus, but rarely arises in other sites, such as the ovary, the pelvic cavity, mesentery, omentum, and serosal or intramural portions of the large intestine. We present a case in which multiple nodules of ESS involving the taenia coli of the ascending colon were accompanied by grossly and radiologically unrecognized small, endometrial stromal lesions (less than 0.5 cm in the greatest dimension) with only focal marginal irregularities in the subsequent hysterectomy specimen. Whether this small sized endometrial stromal tumor is an incidentally associated endometrial stromal nodule (ESN) or a small sized, low grade ESS that was preceded by metastatic lesion is debatable. However, endometrial stromal tumors with tongue-like protrusions and associated fibroblastic stromal reaction around the tumor strongly favored these nodules being the small uterine ESS mimicking ESN. We propose that meticulous search for the detection of uterine ESS is mandatory before making a diagnosis of primary extrauterine ESS even in cases having a grossly or radiologically normal uterus and that the extent of focal irregularities of ESN should be more clearly defined for the correct diagnosis of ESS and ESN.