Mature cystic teratoma is the most common form of ovarian germ cell tumor. Mature cystic teratoma is a benign tumor, mainly diagnosed in young women, with non-specific symptoms. However, the risk of malignant transformation exists (1-2%). Squamous cell carcinoma is the most frequently encountered histological form. Giant colonic diverticulum is a rare complication of diverticular disease, characterized by a diverticulum larger than 4 cm which can sometimes be confused with other digestive pathologies (appendicitis, small bowel perforation ...). We report a case of an ovarian squamous cell carcinoma arising from a mature cystic teratoma, presenting like a sigmoid fistula, with an initial doubt with the diagnosis of a giant colonic diverticulum. A 68-year-old woman was admitted for chronic hypogastric abdominal pain with a doubt concerning the diagnosis between a mature cystic teratoma and a giant colonic diverticulum. A computed tomography scan was performed revealing a perisigmoid cyst with hydro-aeric level in favor of a giant colonic diverticulum. The pelvic MRI rather suggested a left ovarian cyst, fistulated in the sigmoid colon. Finally, the colonoscopy confirmed this hypothesis with the visualization of a sigmoid fistula located 15cm from the anal margin in connection with a cavity containing hairs. Biopsies revealed a squamous cell carcinoma. After a negative extension assessment, a posterior pelvectomy was performed with pelvic and lumbo-aortic lymph node dissection. The pathological diagnosis was an ovarian pT4N1R0 squamous cell carcinoma. An adjuvant chemotherapy is still in progress.
Squamous Cell Carcinoma Arising in Mature Cystic Teratoma of the Ovary
