Abstract
BACKGROUND: Adrenocortical oncocytoma is a rare, mostly benign, nonfunctional tumor that is typically detected incidentally. Its diagnosis is challenging because of the absence of distinctive imaging characteristics, necessitating pathological validation. CASE SUMMARY: We present a case report of a 35-year-old woman with an adrenal mass located on the left side, where endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) was performed after comprehensive diagnostic assessment. Our results are consistent with those of previously documented cases regarding tumor demographics and anatomical location. Given the limited number of reports on this condition, long-term follow-up is crucial to enhance our understanding of its prognosis. CONCLUSION: For patients with adrenocortical oncocytoma, EUS-FNA can enables collection of preoperative tissue specimens leading to suitable treatment strategies.