6625 Adrenocortical Oncocytoma: Illuminating The Clinical And Biological Behavior Of An Extremely Rare Tumor Of The Adrenal Gland

Abstract Disclosure: H. Usmani: None. M. Arguello, MD: None. Background: Only 120 cases of adrenocortical oncocytoma have been reported in English literature (1). Standardized diagnostic criteria, or a typical clinical or biological course, have yet to be established. 58 yo woman with PMH HTN, COPD, CREST syndrome on chronic prednisone, previous 38-pk yr smoker, pulmonary nodule, current vaper, was incidentally found to have a left adrenal mass when she went for CT abd pelvis with IV and oral contrast to evaluate for suspected diverticulosis and anemia. CT showed a mass in the left adrenal gland measuring 5.6 x 4.4 cm in size, heterogeneous in density, with possible areas of necrosis. It is unclear how long the adrenal mass was there since the patient never had a CT scan before. Patient was asymptomatic except 50 lb wt loss in the last couple of years with a feeble appetite, self-reported abnormal hair growth (no hirsutism on exam), voice deepening attributed to smoking, and HTN- well controlled with nifedipine. Patient has no FHx of endocrinopathy. Adrenal function tests wnl except for plasma free normetanephrines slightly high at 1.64 nmol/L, which was unlikely from tumor considering tumor size. Normal adrenal function tests included 11-deoxycortisol, DHEA-S, plasma-free metanephrine, aldosterone, renin, aldosterone: renin ratio, androstenedione, ACTH, 1 mg overnight dexamethasone suppression test.She underwent left-sided lap adrenalectomy 4 mos after discovery of adrenal mass, with no complications. 6 days after surgery, a left in JP drain caught on a door at patient’s home, causing splenic subcapsular tear requiring emergent splenectomy. The path report shows an encapsulated neoplasm consisting of sheet-like proliferation of eosinophilia polygonal cells with nuclear atypia, low mitotic activity, and no capsular or vascular invasion. Immunohistochemical markers show neoplastic cells positive for SF1, Mart1, inhibin (focal), and synaptophysin (focal); negative for CK-OSCAR, CK7, CK20, chromogranin, HMB45, and TTF-1, Ki67 and pHH3 show low proliferative index. The pathology slides were sent to U of M, where the diagnosis of adrenal cortical oncocytoma was made. Removal of oncocytoma has not affected patient’s weight, blood pressure, deep voice, or hair growth on 4 month follow up. Lin-Wiess-bisceglia system (2) suggests a benign lesion. But, as mutation rate for this rare tumor is unclear, plan for CT abd pelvis in 1 yr. Conclusion: This case elucidates the clinical and biological course and pathologic diagnosis of an exceedingly rare adrenal tumor. References: [1] Hong Y, Hao Y, Hu J, Xu B, Shan H, Wang X. Adrenocortical oncocytoma: 11 Case reports and review of the literature. Medicine (Baltimore). 2017 Dec;96(48):e8750. [2] Munoz de Nova JL, García-Sanz Í, del Campo Val L, Delgado Valdueza J, Martín-Pérez E. Oncocitoma: una lesión infrecuente en la glándula suprarrenal. Endocrinol Nutr. 2015;62:144-145. Presentation: 6/1/2024