MON-519 - A Rare Case of an Adrenal Adenoma-Hemangioma Collision Tumor

Introduction
Adrenal collision tumors (ACT’s) are comprised of two adjacent but histologically distinct tumors in the adrenal gland. Though adrenal glands are frequently visualized on cross-sectional imaging of the chest and abdomen, the prevalence of ACT’s is unknown and these tumors are thought to be rare. We present a case of an incidentally diagnosed adrenal adenoma-hemangioma collision tumor.
Case Presentation
A 74-year-old male with a 25-pack year history of tobacco use and hypertension was referred for evaluation of an apparent right adrenal incidentaloma found on a low dose computed tomography (CT) of the chest for lung cancer screening. Lung images were unremarkable, but a 3.2 cm right adrenal mass was visible. Subsequent CT with adrenal protocol confirmed a 3.2 cm right adrenal nodule with pre-contrast intensity < 10 Hounsfield Units (HU) peripherally but > 30 HU centrally. Contrast enhanced images showed heterogeneity of the central tumor and late enhancement of the central component on delayed images consistent with a hemangioma. Review of a contrast enhanced abdominal CT scan obtained June 2012 revealed right adrenal findings essentially identical to the current CT scan. The patient was unaware of the results of earlier imaging. Measurements of fractionated plasma metanephrines, aldosterone, and renin activity were unremarkable. Overnight 1 mg dexamethasone suppression test was notable for 8 AM cortisol of 1.9 g/dL (expected < 1.8) with dexamethasone level 306.5 ng/dL (140-295). However, two of three midnight salivary cortisol measurements were below expected cutoff ( < 0.1 g/dL), and 8 AM ACTH level was 38.5 pg/mL (7.2-63.3).
Discussion
After extensive literature review, this appears to be the fifth reported case of an adrenal adenoma-hemangioma collision tumor. Adenoma-myolipoma appears to be the most common ACT, though distant metastases (breast and lung carcinoma and melanoma), adrenocortical carcinomas, Hodgkin’s lymphoma, pheochromocytomas, ganglioneuromas, and parachordomas have also been reported in adrenal ACT’s. Pathogenesis of ACT’s remains unclear, with occurrence of two different tumors in proximity by chance or a single neoplastic stimulus resulting in two distinct tumors in contiguity the prevailing hypotheses. Magnetic resonance imaging (MRI) can be useful in distinguishing hemangiomas by demonstrating hypointense images on T1 weighted imaging and hyperintense T2 weighted images, though MRI was deferred because current and previous contrast enhanced CT images closely match those for other published adenoma-hemangioma collision tumor cases and the 13 year interval between CT scans without changes in size and appearance of the patient’s adrenal nodule excluded both adrenocortical carcinoma and distant metastases. Adenoma-hemangioma is a rare form of ACT that should be considered in the differential diagnosis of a complex, heterogeneous adrenal mass.

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