A case of ovarian endometrioid carcinoma thought to have developed within chocolate cyst in an undescended ovary in the retroperitoneal cavity

Abstract

Synopsis: Undescended ovary (UO) is an uncommon congenital condition. We present a case of ovarian endometrioid carcinoma thought to have developed in an UO. A 49-year-old female underwent surgery for a suspected appendiceal tumor 9 years ago. Intraoperative findings revealed an ovarian tumor in the retroperitoneal cavity, but the surgery was terminated without tumor removal because of the suspicion of anaphylactic shock. Subsequently, MRI suspected an ovarian chocolate cyst, and the patient was followed up for 9 years with dienogest medication. The patient visited our hospital with right lower abdominal pain and fever complaints, and CT scan revealed a mass in the right retroperitoneal cavity. It was diagnosed as ovarian cancer developed within the chocolate cyst, based on the CT and MRI images and elevated tumor marker levels. Because complications of appendicitis were suspected on the basis of CT images, antibiotic therapy was initiated and surgery was performed. The area around the ileum was abscessed and adhered to the tumor. A right hemicolectomy was performed and the region was resected as a lump, considering the tumor invasion. The postoperative pathological diagnosis was stage IA ovarian endometrioid carcinoma. Malignancy in UO is so uncommon that further accumulation of similar cases is desired.