A case of adrenocortical adenoma harboring venous thrombus mimicking adrenal malignancy

Advances in imaging technology and its widespread use have increased the number of identified patients with bilateral adrenal incidentalomas. The pathology of bilateral adrenal incidentalomas is gradually elucidated by its increased frequency. Although there is no consensus regarding the optimal management of bilateral adrenal lesions, adrenal lesions that are a suspected adrenocortical carcinoma on the basis of radiological imaging require surgical resection. We report a clinically interesting case of a 59-year-old female with adrenocortical adenoma harboring venous thrombus that mimicked adrenal malignancy. She was referred for evaluation of asymptomatic asymmetric lesions on both adrenal glands. Abdominal computed tomography and magnetic resonance imaging showed a 4.7-cm-diameter heterogenous lesion with peripheral enhancement in the right adrenal gland and a 2.0-cm-diameter homogenous lesion in the left adrenal gland. Adrenal scintigraphy with ¹³¹I-adosterol exhibited marked accumulation in the left lesion and slight accumulation in the middle inferior portion of the right lesion. Endocrine data revealed subclinical Cushing syndrome, and the patient underwent right laparoscopic adrenalectomy. The serum cortisol level was not suppressed on an overnight dexamethasone suppression test after the adrenalectomy. The resected tumor revealed a cortisol-producing adrenocortical adenoma harboring an organized and re-canalized venous thrombus, which was associated with focal papillary endothelial hyperplasia. This case illustrates the difficulty with preoperatively diagnosing this heterogeneously enhanced large benign adrenal lesion and differentiating it from adrenocortical carcinoma or angiosarcoma.