Castleman's disease of the retroperitoneum showing high accumulation on FDG-PET scan; report of a case

A 60-year-old woman referred for examination of a retroperitoneal tumor was found in contrast-enhanced CT to have an enhanced, relatively demarcated mass with a small cyst in the retroperitoneal space. F-18 fluorodeoxyglucose positron emission tomography (FDG-PET) showed high accumulation in the tumor. Neuron-specific enolase was 36.0ng /ml, the normal range being less than 10.0ng/ml, necessitating surgery for suspected retroperitoneal malignancy. The resected 77 × 24mm tumor proved histopathologically to be hyaline-vascular Castleman's disease. The postoperative course was uneventful and she has shown no signs of recurrence. Castleman's disease is a relatively rare disorder characterized by the benign proliferation of lymphoid tissue. It is difficult to differentiate malignant retroperitoneal tumor and Castleman's disease because both are positive in FDG-PET.