Integrated imaging of adrenal oncocytoma: a case of diagnostic challenge

Oncocytomas are in most cases benign tumors, usually arising in kidneys as well as thyroid, parathyroid, salivary or pituitary glands (1,2). This kind of tumor is extremely rare in adrenals and it is usually discovered as incidental finding because is nonfunctional; however, in about 20% of cases features suggestive for malignancy and/or adrenal hypersecretion have been reported (3). Tumor size criterion often allows to differentiate a benign from a malignant adrenal mass, but in oncocytic neoplasm neither size lesion nor imaging findings are useful for this purpose; indeed, usually oncocytomas present as large adrenal masses and surgical excision is often required (4,5). Therefore, a careful diagnostic evaluation is recommended for lesion characterization as well as for the assessment of potential malignancy.