Renal oncocytoma remains a diagnostic dilemma: imaging heterogeneity and potential overtreatment in a retrospective cohort.

backgroundRenal oncocytoma (RO) is a benign renal neoplasm that frequently mimics renal cell carcinoma (RCC) on imaging studies, resulting in considerable diagnostic uncertainty and challenges in clinical management. This study aims to characterize the imaging heterogeneity of RO and describe preoperative radiologic recognition and surgical management patterns in a retrospective cohort.

methodsWe retrospectively reviewed 62 patients with pathologically confirmed RO who underwent surgical treatment at a tertiary referral center between January 2020 and June 2025. Clinical characteristics, imaging findings, surgical management, renal tumor biopsy (RTB) results, and follow-up outcomes were analyzed. Preoperative imaging findings and radiologic reports were reviewed to characterize imaging patterns and determine whether RO had been considered in the differential diagnosis before surgery.

resultsMost patients were asymptomatic, with 55 of 62 tumors (88.7%) detected incidentally during routine health examinations. Imaging appearances were highly heterogeneous and included classic stellate scar lesions, small nonspecific solid masses, progressively enhancing lesions, and hyper-vascular RCC-like tumors. Despite pathological confirmation of RO in all cases, preoperative recognition of RO was uncommon, with only one lesion explicitly considered as RO in the available radiologic reports before surgery. The remaining lesions were reported as suspicious for RCC or other malignant renal tumors. All patients underwent surgical treatment, including partial nephrectomy in 41 patients and radical nephrectomy in 21 patients. A retrospective review of the available imaging and clinical information suggests that selected patients who underwent radical nephrectomy might have been considered for nephron-sparing approaches if greater preoperative confidence in the benign nature of the tumor had been available. RTB was performed in four patients, and all biopsy findings were concordant with final pathological diagnosis. No recurrence or metastasis was observed during follow-up.

conclusionsRenal oncocytoma demonstrates substantial radiologic heterogeneity and frequent overlap with RCC on preoperative imaging. In this surgically treated cohort, limited preoperative recognition of RO highlighted the ongoing challenge of characterizing benign renal masses before surgery. Improved diagnostic strategies, including selective renal tumor biopsy and emerging imaging approaches, may enhance individualized treatment selection and support nephron-sparing in appropriately selected patients.