Case of inverted papillary urothelial carcinoma in the ureter

Introduction: Urothelial neoplasms with a varus growth pattern are rare, and few urologists have encountered inverted urothelial carcinoma of the ureter. Case presentation: An 82-year-old man was referred to our hospital for investigation of gross hematuria. Magnetic resonance imaging revealed nodules measuring 1-2 mm in diameter in the left upper ureter with slight reduction in signal intensity on diffusion-weighted imaging. Ureteroscopy showed a pedunculated smooth tumor that had the appearance of an inverted papilloma rather than the papillary shape typical of urothelial carcinoma. The tumor was biopsied and histopathological examination revealed a noninvasive, low-grade urothelial carcinoma with inverted multiple layers. Laparoscopic radical nephroureterectomy was subsequently performed, and a pedunculated tumor measuring 20 mm in diameter was found in the left upper ureter. The histopathological diagnosis was inverted papillary urothelial carcinoma, low-grade, pTa, pN0. Conclusion: This report provides the first clinical description of inverted papillary urothelial carcinoma of the ureter.