SUN-422 - Frozen in Time: A Still Adrenal with Mild Cortisol Autonomy

Introduction: Adrenal incidentalomas are increasingly detected on imaging, with mild autonomous cortisol secretion (MACS) as the most frequent abnormality [1,3,8]. Hemorrhage within an incidentaloma is rare but may mimic malignancy [2]. As about 50% of hemorrhagic lesions are pheochromocytomas and 20% malignant, integrating clinical, biochemical, and imaging data is key to avoid unnecessary surgery [1–3,8,9].
We present a case highlighting the diagnostic and management complexity of an incidental adrenal lesion with concern for hormonal overactivity.

Case Presentation: A 62-year-old man with hypertension, prediabetes, and class III obesity was referred to endocrinology for an incidental 4.8 × 4.2 cm adrenal lesion on CT showing a crescentic hyperdense core, suggesting chronic hemorrhage. MRI confirmed a 4.4 × 4.7 cm non-enhancing lesion with intrinsic T1 hyperintensity and in-phase signal drop, consistent with organized hemorrhage, without interval growth. Patient reported weight gain but no other symptoms of cortisol or catecholamine excess. Examination showed no cushingoid features.

Biochemical testing revealed normal metanephrines, low-normal DHEAS, normal aldosterone/renin ratio, and borderline-suppressed dexamethasone suppression test (DST- 1.2–1.3 µg/dL) with mildly elevated midnight salivary cortisol (0.26 µg/dL), consistent with MACS. A multidisciplinary consensus favored serial imaging and annual hormonal follow-up.

Discussion: MACS is defined by post–1 mg DST cortisol >1.8 µg/dL in an adrenal adenoma without overt Cushing features. Differentiating adrenal hemorrhage from tumors is difficult [1,2]. Acute hemorrhage appears as a high-attenuation, non-enhancing lesion that evolves into a hypoattenuating hematoma, while chronic hemorrhage shows T1/T2 hypointensity from hemosiderin [4]. Absence of growth, enhancement, or hormonal activity supported a benign hemorrhagic adenoma. Hemorrhage may arise from pheochromocytoma, carcinoma, metastases, or anticoagulation [6,7]. Unilateral cases rarely cause insufficiency, but adrenal function should be verified [1,2]. Hormonal testing is best performed outpatient to reduce stress-related false positives [1,4].

The 2023 ESE–ENSAT guidelines recommend surgery for enlarging or functional lesions, while CUA/AUA supports imaging surveillance for stable or hemorrhagic ones [2,3,9]. MACS carries modest cardiometabolic risk and rarely progresses [3,5]. Incorporating ACTH and DHEAS improves diagnostic accuracy [8]. Stable, biochemically indolent lesions have minimal malignant potential, supporting cautious observation [6,9].

Conclusion: MACS with adrenal hemorrhage may radiologically simulate neoplasm but often follows a benign course. Imaging stability and minimal hormonal activity support a guideline-directed surveillance approach as the safest management strategy.

References: 9

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