Lymphoid Structure Presenting as a Hypermetabolic Adrenal Incidentaloma

Adrenal incidentalomas are a frequent cause for consultation in endocrinology. Current guidelines provide an algorithm for their evaluation to determinate the risk of hormonally active or malignant condition. We report a unique case of benign adrenal incidentaloma in a 53-year-old woman with multiple malignancy criteria on contrast-free computed tomography and [¹⁸F]fluorodeoxyglucose positron emission tomography-computed tomography, leading to a left adrenalectomy. Histopathologic analysis showed a 15-mm intra-adrenal lymphoid organ localized in the medulla, without any cellular atypia and organized with a capsule and multiple germinal centers. The surrounding adrenal tissue was unremarkable, and the patient did not develop any inflammatory, infectious, or neoplastic disease during the 2 following years. This is the first described case of a well-organized intra-adrenal ectopic lymphoid organ in the absence of any evident stimulus.