DIAGNOSTIC DILEMMA OF SMALL INCIDENTALLY DISCOVERED ADRENAL MASSES - ROLE FOR I-131 6-BETA-IODOMETHYL-NORCHOLESTEROL SCINTIGRAPHY

Incidentally discovered adrenal masses are detected in 0.35% to 5.00% of patients imaged with computed tomography (CT) for reasons other tha n suspected adrenal pathology, Most small adrenal masses are benign, a lthough malignant tumors less than or equal to 3 cm in diameter are we ll described. In the setting of normal adrenal hormonal secretion, the preferential accumulation of I-131-6 beta-iodomethyl-norcholesterol ( NP59) by adrenocortical tissues allows the distinction of adenomas fro m other space-occupying or destructive lesions, with diagnostic images being obtained in 100% of lesions > 2 cm, Although some lesions less than or equal to 2 cm have yielded nondiagnostic images, the frequency of this phenomenon and thus the utility of NP59 scintigraphy for the evaluation of small adrenal lesions has remained incompletely characte rized. Between January 1976 and December 1994 a total of 166 patients with nonhypersecretory unilateral adrenal masses less than or equal to 3 cm in maximal diameter, discovered incidentally during CT examinati ons of the abdomen or chest for reasons other than clinically suspecte d adrenal disease, were studied with NP59 scintigraphy, Nonhypersecret ory masses less than or equal to 1 cm, > 1 to a 2 cm, and > 2 to a 3 c m yielded diagnostic images in 52%, 89%, and 100% of patients, respect ively. Lesions other than adenomas, including malignancies, > 1 to a 2 cm and > 2 to less than or equal to 3 cm were present in 9% and 10% o f patients, respectively, These findings emphasize the need to determi ne the nature of small incidentally discovered adrenal masses whose ma nagement may alter patient care and confirm the utility of NP59 scinti graphy to evaluate nonhypersecretory adrenal masses regardless of size .