Early abdominal pregnancy complicated by parasitic dermoid cyst: diagnosis by diffusion-weighted magnetic resonance imaging and management by laparoendoscopic single-site surgery.

A 26-year-old primigravida patient was referred with suspicion of ectopic pregnancy 39 days after her last menstrual period. Her serum β-human chorionic gonadotropin value was 3812 mIU/mL. As we suspected the existence of ectopic pregnancy with bilateral dermoid cysts, laparoendoscopic single-site surgery was performed. After dissection of dense pelvic adhesion, cystectomy was performed for a left ovarian dermoid cyst. Although there was a right ovary at the correct position, a parasitic dermoid cyst firmly attached to the peritoneal surface of cul-de-sac was identified. After excision of the parasitic dermoid cyst, early abdominal pregnancy tissue implanted in the peritoneal hollow of right deep pararectal space was identified under the guidance of diffusion-weighted magnetic resonance imaging and was excised. With systemic administration of methotorexate, the postoperative course was uneventful.