Intrarenal urothelial cancers confused as infiltrative renal masses: Report of 22 cases and literature review.

Distinguishing infiltrative renal masses (IRMs) from intrarenal urothelial cancers (IUCs) is critically important, but may be challenging for any radiologist or urologist. The present study aimed to summarize the clinical, imaging and pathological characteristics of IRM, which were postoperatively confirmed as IUC. The analysis was performed using the records of 22 patients who were preoperatively diagnosed with IRM but the results of percutaneous biopsies or postoperative pathological analyses led to diagnoses of urothelial cancers (UCs) from January 2011 to December 2017. The demographic data, computed tomography (CT) imaging features and pathological characteristics were evaluated. The present study also reviewed the literature concerning the IRM and IUC. The mean age of patients was 62 years and 86.4% of them were >55 years. The sex and tumor side distributions were equal. Hematuria and/or flank pain were observed in 86.4% of patients. All patients exhibited endophytic solid renal masses with unclear tumor boundaries on CT images. The kidneys of 81.8% of patients maintained their normal shape while mild alternations were observed in 18.2% of cases. A total of 81.8% of patients maintained the reniform shape and 18.2% exhibited mild contour change. Of all patients, all tumors exhibited less or equal attenuation on unenhanced CT images and they were mildlyimproved on enhanced CT. A total of 6 cases were confirmed by biopsy, when patients underwent laparoscopic nephroureterectomy instead of radical nephrectomy. The remaining 16 patients underwent laparoscopic nephrectomy but the postoperative pathological diagnoses revealed the presence of UCs. All postoperatively confirmed cancers were stages T3 and T4 (62.5 and 37.5%, respectively). UCs should be suspected in middle aged or elderly middle-elderly patients presenting renal masses with endophytic solid unclear tumor boundary on unenhanced and slightly enhanced CT images, accompanied with hematuria and/or flank pain. Preoperative biopsy is preferred for complicated cases.