Castleman disease mimicking an aggressive retroperitoneal neoplasm.

A case of Castleman disease of the retroperitoneum in a 26-year-old woman is presented. Sonography, computed tomography, and magnetic resonance imaging demonstrated a large retroperitoneal mass with somewhat heterogeneous imaging characteristics. Although a definitive preoperative diagnosis was not possible, magnetic resonance imaging was useful in delineating the extent of the tumor and defining the characteristics of surrounding soft tissues.