Papillary urothelial neoplasm of low malignant potential (PUNLMP) is an exophytic (outward growing), (microscopically) nipple-shaped (or papillary) pre-malignant growth of the lining of the upper genitourinary tract (the urothelium), which includes the renal pelvis, ureters, urinary bladder and part of the urethra.

PUNLMP is pronounced pun-lump, like the words pun and lump.

As their name suggests, PUNLMPs are neoplasms, i.e. clonal cellular proliferations, that are thought to have a low probability of developing into urothelial cancer, i.e. a malignancy such as bladder cancer.

PUNLMPs can lead to blood in the urine (hematuria) or may be asymptomatic.^{[citation needed]}

PUNLMPs are exophytic lesions that appear friable to the naked eye and when imaged during cystoscopy. They are definitively diagnosed after removal by microscopic examination by pathologists.^{[citation needed]}

Histologically, they have a papillary architecture with slender fibro vascular cores and rare basal mitoses. The papillae rarely fuse and uncommonly branch. Cytologically, they have uniform nuclear enlargement.^{[citation needed]}

They cannot be reliably differentiated from low grade papillary urothelial carcinomas using cytology,^[1] and their diagnosis (vis-a-vis low grade papillary urothelial carcinoma) has a poor inter-rater reliability.^[2]

Pathologic grading and staging tumors are: graded by the degree of cellular atypia (G1->G3), and staged:^{[citation needed]}

• papilloma
• papillary tumor of low malignant potential (PTLMP)
• papillary urothelial carcinomas low grade
• papillary urothelial carcinomas high grade.

PUNLMPs are treated like non-invasive low grade papillary urothelial carcinomas,^[1] excision and regular follow-up cystoscopies.

There is a rare occurrence of a pelvic recurrence of a low-grade superficial TCC after cystectomy. Delayed presentation with recurrent low-grade urothelial carcinoma is an unusual entity and potential mechanism of traumatic implantation should be considered. Characteristically low-grade tumors are resistant to systemic chemotherapy and curative-intent surgical resection of the tumor should be considered.^{[citation needed]}