ABSTRACT
<p><b>OBJECTIVE</b>To analyze the CT and MRI findings and pathological characteristics of retroperitoneal localized Castleman's disease and discuss the diagnostic and differential value of CT and MRI.</p><p><b>METHODS</b>CT, MRI and clinical data of retroperitoneal localized Castleman's disease, proved by surgery and pathology, of 13 patients were reviewed. Among them, all the 13 cases received CT, and 4 cases received MRI examination.</p><p><b>RESULTS</b>Among the 13 cases, 12 cases were of hyaline vascular type, and one was of mixed type. All foci were single mass and most foci located in the periphery of the kidney. The maximum diameter was 4.2 cm to 8.6 cm and the mean diameter of all tumors was 5.9 cm. The outline of most tumors was clear and kidney-shaped. On unenhanced CT, 10 cases showed low density and 3 cases showed isodensity. On plain MRI, four cases showed iso-signal on T1WI, three cases showed slightly high signal on T2WI and one showed moderately high signal. The CT and MRI findings were similar on contrast enhanced scan. In arterial phase, 10 cases showed moderate enhancement, 2 cases showed significant enhancement and one case showed moderate enhancement. Five cases showed rather homogeneous enhancement and 8 cases showed heterogeneous enhancement.In venous phase, all the 13 tumors showed continuous enhancement. Eight cases showing heterogeneous enhancement in arterial phase showed expanded range, and among them two cases showed tending to be homogeneous enhancement. Six cases showed areas of low density without enhancement, and 9 cases were accompanied with single or multi-satellite punctuate or striped foci around the tumors.</p><p><b>CONCLUSION</b>Dynamic contrast-enhanced CT and MRI combined with MR T2WI fat-suppression are of great importance in the diagnosis and identification of retroperitoneal localized Castleman's disease.</p>