Retroperitoneal fibrosis: ultrasound and CT features

The sonographic and computed tomographic (CT) findings in three cases of retroperitoneal fibrosis are illustrated. Its clinical, laboratory, and conventional radiographic findings are often nonspecific. The sonographic findings consist of an extensive retroperitoneal, extrarenal, anechoic, well marginated, and irregularly contoured mass. Computed tomography depicts a paraspinal, extrarenal, and well marginated lesion that is isodense with the surrounding muscles. Through other abnormalities present similar sonographic and CT findings, the differential diagnosis is limited so that correlation of the clinical and radiographic changes allows a preoperative diagnosis with high confidence.