PSAT030 A Clinically Dormant Adrenal Incidentaloma Evolving to A Cortisol Secreting Adenoma, A Ten Year Follow Up Experience

INTRO: Adrenal incidentalomas (AIs) are found in approximately 3–4% of abdominal computed tomography (CT) scans performed for other reasons. Most of these masses are found to be nonfunctioning. Studies showed that subtle cortisol secretion in AIs and disruption in the hypothalamic-pituitary-adrenal axis are more frequent than expected. Here we report a case of a small AI progressing to a hormone-secreting adrenal mass causing Cushing's syndrome (CS) after a period of a decade, in which dexamethasone suppression test was the confirmatory diagnostic procedure. CASE: 66-year-old woman was referred to Endocrinology in 2007 for assessment of abnormal abdominal CT finding indicating minimal nodularity of the right adrenal gland followed by an MRI performed 2 years later with suspicion of a small adenoma measuring 1.4 cm. Patient's past medical history included coronary artery disease, impaired glucose tolerance controlled by diet. No reported family history of relevant endocrine tumors. At time of initial assessment, functional hormonal baseline workup was normal including ACTH: 23 pg/mL [5-27 pg/mL], AM Cortisol level: 13.6 mcg/dL [4-22 mcg/dL], 24h U-Cortisol: 16.4 mcg/24h/1g Cr [4-50 mcg/24h/1g], and DHEAS: 30 mcg/dL [<185 mcg/dL] Patient was re-evaluated annually. Over the course of the follow-up, she was found to have poor healing after surgical repair of ankle fracture in 2012, as well as depression necessitating medical therapy in 2015. Her previously diet-controlled diabetes significantly progressed, requiring combination therapy and ultimately basal/bolus insulin. Moreover, patient developed hypertension with antihypertensive medication doses increased from Valsartan 40mg to Valsartan/HCT 80/12.5 in a 5-year period. The patient was found to have normal ACTH, serum, and urine cortisol levels throughout her follow-up period. Annual CT imaging demonstrated no change in right adrenal mass. In 2017, overnight low dose dexamethasone suppression test was found to be 16.2 mcg/dL[<1.8 mcg/dL], which is significantly increased from 0.9 mcg/dL in 2011. In 2018, CT abdomen showed a marked increase in the adrenal mass size to 2.8 cm. In 2020, she underwent right-sided adrenalectomy with no complications. Both blood pressure and glucose levels improved postoperatively. The preoperative use of mifepristone therapy controlled her blood sugar and pressure and eliminated the need for postoperative glucocorticoid replacement. She is currently controlled on diet and lifestyle modifications alone. DISCUSSION: Our case highlights the limitations of current guidelines in the management of AIs that recommend discontinuing annual follow-up if no significant growth occurs after 5 years. Careful long-term follow-up of AIs provides an opportunity to detect the subclinical hormonal alterations, development of new hormonal abnormalities, or any change in mass size. These findings indicate the need for good communication between radiology, primary care, and endocrine providers to assure periodic hormonal and morphological evaluation. This case also suggests that the dexamethasone suppression test may be useful in the evaluation of CS in patients without significant hypercortisolemia. Presentation: Saturday, June 11, 2022 1:00 p.m. - 3:00 p.m.