Castleman Disease is a rare nonneoplastic lymphoproliferative disorder that can be found in any lymph node station with unknown etiology. The current cumulative number of reported cases is minimal. We report a case of a 44-year-old woman with a hard mass in the pelvic retroperitoneal that has been gradually increasing in size for many years. Abdominopelvic MRI scan showed a left retroperitoneal mass and visible calcifications. The patient underwent resection of the left retroperitoneal mass and the pathological diagnosis was Castleman disease of hyaline vascular type.