FRI220 Primary Bilateral Macronodular Adrenal Hyperplasia: A Rare Cause Of Cushing Syndrome

Disclosure: Y. Ortiz: None. A.M. Aviles Melendez: None. M.M. Mangual Garcia: None. J.M. Garcia-Mateo: None. Primary bilateral macronodular adrenal hyperplasia (PBMAH) is a highly heterogenous entity whose pathophysiology remains largely unclear, representing less than 2% of Cushing syndrome (CS) cases, which leads to a challenging diagnosis. Many patients have a mild clinical picture and remain undiagnosed until abdominal imaging for unrelated reasons reveals bilateral adrenal enlargement. Hereby, we describe the case of a patient presented with abdominal pain and clinical hypercortisolism due to PBMAH. Case of a 42-year-old female with past medical history of arterial hypertension, referred for evaluation due to bilateral adrenal masses found on abdominal CT scan performed after patient presented with abdominal discomfort. On initial evaluation, patient refers a 50 pounds weight gain, increase in abdominal circumference, muscle weakness and sudden onset of facial and abdominal hair growth. Physical examination reveals dorsocervical fat pad, proximal muscle weakness, moon facies, facial and abdominal hirsutism. Abdominal CT scan with adrenal protocol showed bilateral adrenal lesions, with largest measuring 2.8 and 3.9 cm on the left side, with attenuation of 16 and 7.4 Hounsfield units. The absolute and relative washouts for the first were 76.6% and 61.6%, and for the second 73.5% and 67.1%, both consistent with adenomas. Laboratory results showed late night salivary cortisol levels of 4.60 ug/dl and 4.80 ug/dl, values which may be high or even normal due to ineffective steroidogenesis on PBMAH. Other labs consisted of low dose 1 mg dexamethasone suppression test: 4.80 ug/dl, and ACTH level: 9.60 pg/ml, which confirms clinical hypercortisolism, indeterminate for ACTH-independent cause. Desmopressin test was not performed, since levels may not be fully suppressed in PBMAH due to ectopic production by adrenal glands, leading to an erroneous diagnosis of ACTH-dependent CS. DHEA level of 618 ug/dl can also be increased, which could lead to a diagnosis of adrenocortical carcinoma. Considering risk of recurrence, risk for adrenal insufficiency, and lower documented complications, unilateral left-sided adrenalectomy was chosen as the best surgical treatment, despite bilateral adrenalectomy being the gold standard for diagnosis. Surgical pathology report showed Adrenocortical adenoma with associated myelolipomatous foci of 7.5 cm in greatest dimension. Despite limited data regarding unilateral adrenalectomy, it appears to convey clinical and biochemical benefits in most cases. Initial remission reported reaches more than 90% with low risk of recurrence between 10-15%. Adrenal insufficiency, despite the presence of residual hyperplastic adrenal tissue, occurs in about one-third of patients and is usually transient. Our case is a great example of the importance of individualization of management options based on therapy benefits, and decreased risks of future complications. Presentation: Friday, June 16, 2023