(4) A Case of Very Large Endometrioma in an Adolescent without Associated Mullerian Anomaly

Background: Recent literature demonstrates the presence of advanced endometriosis in teens. However, there are limited publications describing large endometriomas in adolescents. This case report presents a large complex ovarian mass, found to be an endometrioma on initial surgery. Further surgery was required for optimal treatment of the disease.

Case: A 17-year-old cis female was referred with a large pelvic mass, left-lower quadrant pain, early satiety, and vomiting. She had irregular periods and severe dysmenorrhea since menarche. Her medical history was positive for anxiety. A pelvic ultrasound revealed a complex 21x19x8 cm multiseptated pelvic mass. Further investigations, including tumor markers, revealed a CA-125 at 86 kU/L. MRI demonstrated a multiloculated cyst with bright T2 signal, thin internal septations and several low T2 mural nodules. There was no bright T1 fat-sat signal. The favored diagnosis was a mucinous cystadenoma, arising from the right ovary.

She was consented for a mini-laparotomy and ovarian cystectomy. At surgery, the pelvic survey revealed diffuse, dense adherences and advanced endometriosis. The lesion was not amenable to cystectomy through the incision without risking trauma to surrounding structures. A biopsy and drainage of the lesion were performed.

After a repeat ultrasound, the minimally invasive surgery team was consulted, and she was consented for a diagnostic laparoscopy, ovarian cystectomy and endometriosis treatment. The diagnostic laparoscopy revealed a normal uterus with a fibrotic endometriotic lesion at the cervicovaginal junction. A 15 cm right endometrioma with a normal right fallopian tube were noted. Dense fibrotic endometriotic implants were encasing the right ureter and internal iliac artery together. A right ovarian cystectomy with right ureterolysis and excision of deep, infiltrating endometriosis were performed.

Comments: A systematic review from 2017 reported a 25-32.5% prevalence of endometriosis in adolescents with chronic pain. About one in three had advanced disease based on the r-AFS classification, mainly presenting with endometrioma. However, there are limited reports of very large endometrioma in young patients. A retrospective study looking specifically at patients ages 17-24-year-old undergoing surgery for endometrioma treatment reported cysts smaller than 10 cm in all 63 patients.

This case is a rare presentation of a very large endometrioma in a teenager without associated Mullerian anomaly. This report highlights the importance of considering endometriomas as part of the differential diagnosis of very large pelvic masses in teens, despite normal Mullerian anatomy.