Su1581 Role of Endoscopic Ultrasound (EUS) Evaluating Patients With Adrenal Gland Enlargement or Mass Melissa Martinez Mateo*, Julia K. Leblanc, Mohammad a. AL-Haddad, Stuart Sherman, John Dewitt Gastroenterology, Indiana University School of Medicine, indianapolis, IN Introduction: Studies evaluating the role of EUS-FNA(fine needle aspiration) in adrenal lesions are limited to patients with lung cancer or other malignancy and, generally lack long-term follow-up of benign lesions, surgical correlation, and description of its clinical impact. This study aims to report the utility and clinical impact of EUS-FNA of adrenal masses at our institution over a 15 year period. Methods: In a retrospective single-center case series, we identified consecutive patients from 10/97 to 12/11 who had EUS-FNA of either adrenal gland. The following were retrieved from medical records: EUS indications, findings, pathology, complications and follow-up abdominal imaging (CT or MRI) or surgery. Benign EUS-FNA adrenal cytology (anything without definitive malignancy) was considered correct if follow-up imaging at 4months showed the lesion increased 1cm of the original size. Results: 94 patients (52% male, median age 66 years, range: 32-86), had EUS-FNA (median 3 passes; range 1-7) of the left (n 90) and/or right (n 5) adrenal without complications. The median maximal adrenal diameter was 2.4 cm (range 0.7-8). Procedure indications: cancer staging (n 26) or, suspected recurrence (n 5), pancreatic (n 20), mediastinal (n 10), adrenal (n 7), lung (n 7) mass or other (n 19). Previous CT showed adrenal gland enlargement or mass in 59%. Twenty-five (26%) biopsies were malignant: metastatic lung (n 10), esophageal (n 5), colon (n 2), pancreatic (n 2), or other cancers (n 6). Nine (10%) biopsies were non-diagnostic and follow up in these CT showed a stable lesion in 5 but, was unavailable in 4. Sixty (64%) were benign: aldosteronoma (n 1), pheochromocytoma (n 1), paraganglioma (n 1) and adenomas/benign adrenal tissue (n 57). Available follow-up in 36/60 (60%) benign lesions showed: stable size by imaging in 27, confirmation as benign in 5 by repeat EUS-FNA (n 1) or adrenalectomy (n 4), or cancer in 4 by later CT-guided adrenal biopsy (metastatic NSCLC in one, neuroendocrine cancer in one), enlargement of previous and new contralateral adrenal mass on repeat CT (NSCLC in one), or adrenalectomy (adrenocortical carcinoma in one). Follow-up was unavailable in 24/60 (40%) benign biopsies. EUS-FNA of either adrenal made initial the diagnosis of stage IV cancer in 17, cancer recurrence in 7, and ruled out metastasis in 10 patients with underlying malignancy and available follow-up. For patients with malignant or benign cytology and available follow-up (n 61), the sensitivity, specificity, PPV and NPV of adrenal EUS-FNA for malignancy was 86% (CI 68-95%), 97% (CI 83-100%), 96% (CI 79-100%) and 89% (CI 74-96%) respectively. Conclusion: Adrenal gland EUS-FNA is a safe, minimally invasive and sensitive technique with significant impact in the management of patients with adrenal gland mass or enlargement.