CYSTIC ADRENAL LESIONS - CT FEATURES

PURPOSE: To define computed tomographic (CT) features of cystic adrena l lesions that differentiate them from similar-appearing adenoma. MATE RIALS AND METHODS: CT scans of 13 cystic adrenal lesions (four endothe lial cysts, three benign pseudocysts, one nonspecific benign cyst one carcinoma, one pheochromocytoma, and three stable lesions with no hist ologic diagnosis) were analyzed retrospectively. Reports in the litera ture of 26 benign adrenal cysts were also reviewed. RESULTS: Mean lesi on diameter was 6.2 em, and six lesions were less than 5.0 cm. Mean at tenuation value was 21 HU, and in eight cases it was less than 15 HU. Partial adrenal involvement was noted in six cases. Ten lesions contai ned wall or septal calcification. Wall thickness was 3 mm or less in n ine and exceeded 6 mm in three lesions; one of the latter was cystic c arcinoma. Wall enhancement (but no intralesional enhancement) was foun d in two of six lesions. Of 37 reviewed benign cysts, 19 had mural and seven had central calcification, 28 were unilocular, and seven had hi gh attenuation value. Wall thickness was 3 mm or less in 31 lesions. C ONCLUSION: CT findings of a nonenhancing mass with or without wall cal cification allow differentiation of adrenal cyst from adenoma. A small adrenal cyst with near-water attenuation and a thin (less than or equ al to 3-mm) wall is likely to be benign.