Risk of malignancy in patients with incidentally discovered adrenal masses. Accuracy of CT-scan, MRI, norcholesterol scintigraphy, and image-guided FNA cytology. A prospective study

Background: Incidentally discovered adrenal masses has become a common finding during abdominal CT-scan or magnetic resonance imaging (MRI), but unfortunately no defined criteria have been establish to exclude malignancy before surgery. The aim of this study was to compare the sensitivity, specificity, and accuracy of preoperative imaging studies and image-guided fine-needle aspiration (FNA) cytology in patients with nonfunctioning adrenal masses. Patients and Methods: Forty-two consecutive patients with nonfunctioning unilateral adrenal masses incidentally discovered during abdominal CT-scan underwent further evaluation before adrenalectomy. There were 18 (42.9%) men and 24 (57.1%) women with an overall median age of 54 years (range 25-75 years). All patients underwent image-guided FNA cytology, 33 (78.6%) underwent MRI, and 26 (61.9%) underwent norcholesterol adrenal scintigraphy (NCS). Reasons for surgery were one or more of the following: (1) greatest diameter of the mass 4 cm or more (n=36), (2) suspicious appearance on CT-scan (n = 15), MRI (n=14) or both, (3) no uptake (n=10) or increased uptake (n=3) on NCS, (4) smears reading malignancy (n=14), and (5) increasing in size of the mass during follow-up (n=l). Results: Final pathology showed 27 (64.3%) benign adrenal masses (23 adrenocortical adenomas, two ganglioneuromas, and two benign pheochromocytomas), and 15 (35.7%) adrenal malignancies (11 adrenocortical carcinomas and 4 unsuspected adrenal metastases). There were 9 of 27 patients with benign adrenal masses of 6 cm or more in the greatest diameter. The sensitivity, specificity, and accuracy were: 73%, 85%, and 81% for TCscan, 93%, 95%, and 94% for MRI, 90%, 94%, and 92% for NCS, and 93%, 100%, 97% for FNA cytology. FNA cytology and NCS or MRI together reached 100% sensitivity, specificity and accuracy. Conclusions: Image-guided FNAcytology, in conjunction with NCS or MRI, represents an useful procedure, may reveal unsuspected adrenal malignancies, and should be performed in all patients with nonfunctioning adrenal masses before surgical planning.