Malignant transformation of deep infiltrating endometriosis at the uterosacral ligament to endometrioid adenocarcinoma: a rare Case Report

Background The malignant transformation of endometriosis has garnered widespread attention; however, most cases of malignant transformation occur in ovarian endometriomas, while extraovarian malignant transformation is rare. We present an uncommon instance of extraovarian endometrioid adenocarcinoma originating from the uterosacral ligament(USL) in a 41-year-old female, which emerged from deep infiltrating endometriosis of the uterosacral ligament 4 years after a previous clinical diagnosis of adenomyosis. Case presentation A 41-year-old woman, presenting with progressively worsening secondary dysmenorrhea for 4 years and dyspareunia for over 1 year, underwent “laparoscopic total hysterectomy, left adnexectomy, right salpingectomy, right ovarian endometrioma cystectomy, bilateral uterosacral ligament DIE lesion resection, anterior rectal resection, rectal DIE lesion resection with end-to-end anastomosis, left ureteral DIE lesion excision, and pelvic adhesiolysis.” Postoperative pathology revealed a well-differentiated endometrioid adenocarcinoma of the uterosacral ligament (FIGO grade 1), arising from malignant transformation of pelvic endometriosis. Subsequently, a completion surgery was performed, consisting of “transabdominal right oophorectomy, pelvic and para-aortic lymphadenectomy, omentectomy, biopsy of an ileal surface lesion, resection of a right pelvic wall peritoneal lesion, and pelvic adhesiolysis.” Postoperative pathological examination revealed a metastatic carcinoma in the right obturator lymph node. The final diagnosis was stage IV according to the FIGO 2009 staging system (FIGO stage IV) pelvic endometriosis-associated malignancy with direct invasion of the rectal wall by the USL adenocarcinoma. The patient underwent six cycles of adjuvant chemotherapy with paclitaxel and carboplatin given every three weeks. Over five years after finishing treatment, there are no signs of recurrence. Conclusion This paper describes an unusual case where deep infiltrating endometriosis of the uterosacral ligament led to malignant transformation. During long-term treatment and surgery for endometriosis, the potential for malignant transformation and the malignant characteristics of endometriosis should be fully considered. Prompt and thorough surgical intervention is crucial.