Introduction

Abstract

Various tumors can arise from the pelvocalyces and ureter. Transitional cell carcinoma is the most common tumor arising from urothelium, followed by squamous cell carcinoma, adenocarcinoma, and other carcinomas. Benign tumors arising from urothelium—papilloma and inverted papilloma—are less common than urothelial carcinoma. Urothelial carcinoma appears as the intraluminal mass or wall thickening of the pelvocalyces and ureter with hydronephrosis. Its characteristics are multiplicity, centrifugal growth, and preservation of the renal contour. Tumors arising from mesodermal tissues are less frequent than tumors arising from urothelium. Fibroepithelial polyp is the most common tumor among them. Ureteral or periureteral metastasis can occur by hematogenous route, lymphangitic spread or direct invasion by adjacent malignant tumors. The most common primary cancer is stomach cancer. It shows irregular wall thickening of the ureter, periureteral fat infiltration, and hydroureteronephrosis in computed tomography.