Challenging the Diagnosis: An Adrenal Oncocytoma Simulating Adrenocortical Carcinoma

Adrenal oncocytomas are rare adrenal tumors, typically benign and non-functioning. Their clinical and imaging features often overlap with malignant lesions, making diagnosis difficult. We report a 25-year-old male with right hypochondrial pain. Imaging revealed an 18 cm right adrenal mass with indeterminate features on CT and MRI. Hormonal evaluation confirmed a non-functioning lesion. The patient underwent right adrenalectomy. Histology confirmed a benign adrenocortical oncocytic neoplasm based on the Lin-Weiss-Bisceglia criteria. No recurrence was noted at 1-year follow-up. This case highlights the diagnostic challenges of large adrenal tumors and the importance of surgical excision in indeterminate cases. Despite benign histology, imaging features can mimic adrenocortical carcinoma. Adrenal oncocytomas can present diagnostic dilemmas. Surgery remains both diagnostic and therapeutic, with favorable outcomes following complete resection.