A malignant neoplasm arising from the transitional epithelium, usually affecting the urinary bladder, ureter, or renal pelvis. It may or may not have a papillary configuration. It is graded 1 to 3 or 4 according to the degree of cellular differentiation and architectural patterns. Grade 1 transitional cell carcinoma is histologically benign but it may recur. Transitional cell carcinomas may also affect the upper respiratory tract and the ovaries.