SUN-428 - Diagnostic Conundrum: A Functional Hemorrhagic Adrenal Mass with Conflicting Biochemical and Pathological Features

Adrenal incidentalomas are seen in 1 - 6% of adults. Most are benign, non-functional adenomas. Some are functional and represent pheochromocytoma or malignancy. With imaging or pathology alone, adenomas with hemorrhagic or cystic changes can resemble other etiologies.

An asymptomatic 71-year-old male with hyperlipidemia was evaluated for an adrenal mass. He denied known adrenal disease. His exam and vitals were normal. Three weeks prior, he started metoprolol succinate, apixaban, and amiodarone for new atrial fibrillation. CT angiogram was done to rule out pulmonary embolism after ultrasound showed right ventricle dilation. A heterogenous 6.5 × 5.4 × 5.5 cm left adrenal mass with over 40 Hounsfield units was noted. A prior MRI showed a 3.6 × 2.9 cm T1 hyperintense hemorrhagic component with irregular peripheral enhancement and thickening.

Biochemical testing showed normal plasma metanephrine levels (0.32 nmol/L; ref: 0.00-0.49), morning cortisol of 2.0 µg/dL after low-dose oral dexamethasone suppression test (ref: at most 1.8), renin activity level less than 0.1 ng/mL/hr (ref: 0.2-1.6, supine), and serum aldosterone of 10.6 ng/dL (ref: at most 16.0, supine). The aldosterone-to-renin ratio (ARR) was 106 ng/dL per ng/ml/hr, suggesting hyperaldosteronism. The ACTH level was 23.2 pg/mL (ref: 7.2-63.3) and DHEA-S level was 458.3 µg/dL (ref: 650-3400), suggesting adrenal-origin cortisol secretion. Without clear Cushing syndrome features, the cortisol secretion was attributed to mild autonomous cortisol secretion with aldosterone co-secretion from the adrenal mass.

After a left adrenalectomy, the lesion was diagnosed as a benign endothelial adrenal cyst which was discordant with lab results as endothelial cysts are usually hormonally inactive. On re-evaluation, the lesion was diagnosed as an adrenocortical adenoma with extensive hemorrhagic and cystic changes.

This case involved many diagnostic challenges. First, the CT imaging characteristics were non-specific to any particular diagnosis. Also, CT contrast may have falsely elevated the number of Hounsfield units, making interpretation tricky. Next, the lab results were consistent with co-secretion of cortisol and aldosterone. However, the ARR was skewed by beta-blocker use as they can suppress renin release without similarly affecting aldosterone. Lastly, we suspect the lesion’s hemorrhagic appearance on pathology led to the misdiagnosis of an endothelial cyst, since they are highly vascularized structures. Based on these challenges, we advise an integrated approach of imaging, labs, and pathology toward timely and accurate diagnosis of adrenal lesions.

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