Ovarian dermoid cyst complicated by small bowel obstruction, entero-ovarian fistula formation, and malignant degeneration

Dermoid cysts, or mature cystic teratomas, are complicated by malignant degeneration in only 1–2% of cases. Rarely, dermoid cysts result in complications of small bowel obstruction or entero-ovarian fistula formation. In the current report we present the case of a 59-year-old female with a known dermoid cyst who presented with leukocytosis and was discovered to have a small bowel obstruction at the level of an ileo-ovarian fistula. The patient was taken to the operating room and was treated with total abdominal hysterectomy, bilateral salpingo-oopherectomy, and short segment small bowel resection. Review of the surgical pathology revealed areas of malignant degeneration within the dermoid cyst to squamous cell carcinoma. To our knowledge, this is only the second reported case of an ovarian dermoid cyst complicated by small bowel obstruction, entero-ovarian fistula formation, and malignant degeneration. •Mature cystic teratomas (MCTs) are the most common germ cell neoplasm.•Only 1-2% of MCTs will undergo malignant degeneration.•Fistulization of MCTs into adjacent bowel has been reported in only 29 prior cases.•Small bowel obstruction (SBO) related to a MCT has been reported in 7 prior cases.•We report MCT-related SBO, fistula, and malignant degeneration occurring together.