Noninvasive papillary lesions of the bladder can be benign, have malignant potential, or contain either low-grade or high-grade papillary urothelial carcinoma.

• Urothelial papilloma – Benign lesions of the bladder, often occurring with increased frequency in young adults and children. Hematuria is a common presenting symptom.
• Inverted papilloma – Benign tumors that originate from the overlying mucosa and grow into the stroma. They most often occur in men in their 50s-60s and most often present with hematuria or irritative symptoms.
• Papillary urothelial neoplasm of low malignant potential (PUNLMP) – Resembles urothelial papilloma, but is distinguished by thickening of the urothelium and frequently recurs following resection.
• Noninvasive low-grade papillary urothelial carcinoma (LGPUC) – Characterized by orderly appearance of the urothelial lining but with variation in architectural and cytologic atypia, often involving the posterior or lateral bladder wall. These tend to recur, but progression to invasive tumors is rare.
• Noninvasive high-grade papillary urothelial carcinoma (HGPUC) – Characterized by disorderly appearance of urothelial lining papillary fronds with marked architectural and cytologic abnormalities. These tend to be invasive at diagnosis and have a high potential for malignant transformation.