Non-invasive papillary urothelial carcinoma, low-grade of the renal pelvis mimicking a xanthogranulomatous pyelonephritis in a male patient: A case report and review of literature.

We report on a 31-year-old male patient with non-invasive papillary urothelial carcinoma, low grade of the renal pelvis disguised as xanthogranulomatous pyelonephritis. The only symptom of the patient was lower back pain. The initial renal-enhanced computed tomography, magnetic resonance imaging and contrast-enhanced ultrasonography showed that the right kidney had a benign lesion and this inflammatory lesion might be xanthogranulomatous pyelonephritis. A percutaneous renal biopsy was performed and histopathologic examination revealed a xanthogranulomatous pyelonephritis. Initially, we diagnosed it as xanthogranulomatous pyelonephritis and treated it with antibiotics. One and a half years later, the patient suffered from back pain again. The lesion increased significantly and a right renal pelvic lesion with retroperitoneal lymphadenopathy was considered a malignant lesion on computed tomography scan. Therefore, radical resection of right renal pelvis carcinoma was performed under retroperitoneal laparoscopy. Intraoperative frozen section was reported as right renal urothelial carcinoma with no metastasis in renal hilar lymph node. Postoperative histopathologic examination revealed non-invasive papillary urothelial carcinoma, low grade of renal pelvis.