7428 Clinical and Radiological Characterization and Outcomes of Lipid-Poor Adrenal Masses- A Multi-Center Retrospective Study

Abstract Disclosure: V. Balderrama-Brondani: None. R. Al-ward: None. K. Kiseljak-Vassiliades: None. L.M. Fishbein: None. D.A. Kirelik: None. O. Hamidi: None. R. Pishdad: None. H.K. Ghayee: None. M. Sukkari: None. S.S. Bedrose: None. A.H. Hamrahian: None. M.A. Habra: None. Background: Lipid-poor adrenal masses (LPAMs) with pre-contrast radiodensity >10 Hounsfield Units (HU) on computed tomography (CT) represent ∼25% of adrenal tumors. There is limited data about the natural history of LPAMs; therefore, we evaluated a large series of patients with LPAMs to describe the radiological and clinical features and outcomes of these cases. Methods: We conducted a multi-center retrospective cohort study of patients with LPAMs with a baseline diameter of 10-39 mm and derived from 6 institution members of the American-Australian-Asian Adrenal Alliance (A5). We excluded suspected or proven adrenal metastasis, pheochromocytoma, sarcoma, lymphoma, myelolipoma, infiltrative lesions, and adrenal hemorrhage, as well as patients with personal/familial history of genetic predisposition to adrenal neoplasms. The data is presented in percentage and median (range). Results: A total of 242 adrenal masses from 218 patients were evaluated, but only 225 (93%) masses met the inclusion criteria and were analyzed. The age was 58 (23-92), and 61% were women. LPAMs were incidentally discovered in 155 (71.1%) cases, 32 (14.7%) cases were diagnosed due to hormonal overproduction, and 17 (7.8%) due to pain/mass effect. Forty-six (21.1%) patients were on surveillance for a history of extra adrenal malignancy. Masses were unilateral in 89.9% (left side, 57.1%), with size 21 (10-38) mm, with a pre-contrast density of 24 (11-136) HU. Absolute washout was reported in 107 LPAMs and was >60% in 73 (68.2%) cases. The follow-up time was 44.4 (0.9-241) months. Hormonal overproduction developed during the follow-up in 23 (10.5%) cases as follows: cortisol in 15 (6.9%), aldosterone in 4 (1.8%), and sex hormones in 3 (1.4%) cases. LPAM growth rate was 0.03 (-2.18-11.59) cm/year. Seventy-one masses (31.5%) underwent diagnostic procedures (surgery/biopsy) with adrenocortical adenoma (n=37; 52.1%) and adrenocortical carcinoma (ACC) (n=25; 35.2%) being the two most common diagnoses. The tumor growth rate of pathologically confirmed adenomas was 0.03 (-0.30-10.50) cm/year, and of ACC was 1.31 (0.03-11.59) cm/year. A total of 154 (68.4%) LPAMs remained under surveillance at the end of the study, with a follow-up time of 51.8 (6-241) months and a tumor growth rate of 0.02 (-2.18-1.36) cm/year. Forty-five (20.6%) LPAMs decreased by 2 mm (1-13) during the study period. Cases that proved to be ACC had the most significant tumor growth rate over the study (p<0.001). The median time between the initial discovery of LPAM and the surgical resection of ACC cases was 34 (6-128) months. Conclusion: Our study showed that LPAMs carry significant malignant potential, and close long-term follow-up is warranted when surgical resection is not pursued. Prospective studies are critically needed to validate our findings and to establish high-risk molecular, imaging, and biochemical features associated with malignancy. Presentation: 6/2/2024