Abstract: Background and purpose: At present, imaging examination is an important method for the diagnosis of renal oncocytoma. Our study summarized the CT manifestations of renal oncocytoma in order to promote clinicians’ understanding of renal oncocytoma and improve the accuracy of diagnosis. Methods: There were 66 patients with pathologically confirmed renal oncocytoma in Fudan University Shanghai Cancer Center from July 2008 to October 2017. Among them, there were 17 patients who underwent abdominal CT enhancement examination before operation without treatment or biopsy prior to CT examination. The clinical data and preoperative CT images of 17 patients were retrospectively reviewed. Results: Among the 17 patients, 9 patients were male and 8 patients were female. Patients’ ages ranged from 31 to 69 years, and the median age was 59 years. Each patient had a single lesion. Most tumors were spherical. The maximum diameter of tumors ranged from 18 to 100 mm, and the average maximum diameter was (39.0±26.8) mm. Most cases (15/17, 88.2%) showed obvious enhancement but less than the enhancement of renal cortex (average ratio of lesion-to-cortex attenuation: 0.78±0.19). Nephrographic phase images often showed a prolonged enhancement compared with the corticomedullary phase (15/17, 88.2%). There were 7 cases (41.2%) having stellate scar. Five cases (29.4%) showed segmental enhancement inversion. Conclusion: Most of the renal oncocytomas demonstrate obvious prolonged enhancement, sometimes accompanied by segmental enhancement inversion and stellate scars. These CT features may suggest the diagnosis of renal oncocytoma.

Key words: Renal oncocytoma, CT, Prolonged enhancement, Segmental enhancement inversion