Retroperitoneal neurilemoma: CT and MR findings

Our objective was to characterize the CT and MR imaging findings of retroperitoneal neurilemomas. We reviewed the CT and MR imaging findings in six women with retroperitoneal neurilemomas. Retroperitoneal neurilemomas were round, 5-13 cm in diameter, and located in the presacral pelvic retroperitoneum in four patients and adjacent to the kidney in two patients. CT findings of the tumors were well-demarcated round masses showing prominent cystic changes and oriented in a somewhat radial fashion. Medium and heavily T2-weighted MR images showed high-intensity necrotic areas and nonnecrotic areas of various signal intensity. CT findings of a round mass with prominent cystic degeneration, along with certain MR imaging characteristics, may be helpful in the preoperative diagnosis of retroperitoneal neurilemomas.