A rare case of primary extrauterine endometrial stromal sarcoma involving the sigmoid colon

Endometrial stromal sarcoma (ESS) is a rare type of endometrial mesenchymal neoplasm that commonly affects the uterus. The authors report an unusual case of sigmoid colonic ESS. A 46-year-old woman, complaining hematochezia and chronic abdominal pain, was diagnosed with ESS in the sigmoid colon. The patient underwent laparoscopic sigmoid colon resection and had no adjuvant therapy postoperatively. Two years later, the patient developed a new symptom of irregular vaginal bleeding with cervical myoma measuring about 9.0 cm, then a laparoscopic hysterectomy with a bilateral salpingo-oophorectomy was performed. Microscopically, the mass was diagnosed as adenomyosis and low-grade ESS. This case highlights the rarity of extrauterine ESS in the sigmoid colon, especially in the absence of a known history of primary uterine ESS. If the patient underwent prophylactic hysterectomy and adnexectomy after sigmoid colon resection, the recurrence would have been probably delayed.