A Case of Resection of Giant Retroperitoneal Dermoid Cyst Associated with Urinary System Defect

Abstract

The case involved a 38-year-old man who was referred to our hospital for further evaluation and treatment after abdominal ultrasonography during a health checkup revealed a mass in the right abdomen. Magnetic resonance imaging (MRI) performed by a previous physician revealed a large right retroperitoneal tumor. Although the patient was asymptomatic, computed tomography (CT) revealed a giant cystic mass in the right retroperitoneum measuring 34 × 22 × 21 cm. The cyst wall showed mild thickening in some areas, and numerous small nodules, 5-8 mm in size, were observed on the cranio-ventral side of the cyst. The abdominal organs were displaced to the left, and a defect in the right urinary tract was noted. Based on the CT and MRI findings, a diagnosis of mature cystic teratoma was suspected, and surgery was planned owing to the risk of malignancy. Complete open surgical resection was performed, and the final pathological diagnosis was a dermoid cyst. Retroperitoneal dermoid cysts are relatively rare, and this case, involving a defect in the renal and urinary tract systems, is considered extremely rare and has not been previously reported.