Adrenocortical Oncocytoma With Borderline Malignant Potential Causing Subclinical Cushing Syndrome

Objective: To report a rare case of large adrenocortical oncocytoma in a young patient that was successfully resected by a minimally invasive laparoscopic technique in a community hospital. Methods: Clinical case presentation and review of literature. Results: A 36-year-old male patient was found to have an 8-cm right adrenal mass on magnetic resonance imaging (MRI) of the lumbosacral region that was done to rule out lumbar disc disease. The patient was asymptomatic, but due to concerns of malignancy, further work-up was pursued. Biochemical endocrine studies demonstrated subclinical Cushing syndrome. The patient underwent laparoscopic right adrenalectomy. The final size of the mass was 11 cm, which was larger than the MRI reporting. The final pathology of the mass was consistent with adrenocortical oncocytoma with borderline malignant potential. Conclusion: Functioning adrenocortical oncocytoma with borderline malignant potential is a rare tumor. Only about 25 cases of functional adrenocortical oncocytoma have been reported worldwide. The clinical significance of our case highlights the important differential diagnosis of incidental adrenal masses. In our case, a minimally invasive laparoscopic resection of the tumor was successfully performed despite its relatively large size.