papillary urothelial neoplasm of low malignant potential

Papillary urothelial neoplasms of low malignant potential (PUNLMP) show urothelial thickening but lack cytologic features of malignancy.

The image shows several papillary fragments with an orderly arrangement of cells. Umbrella cell layer can be recognized even at low magnification.

PUNLMPs are characterized by a homogenous monotonous appearance, normal to slightly enlarged nuclei and inconspicuous nucleoli. Mitotic figures are uncommon and, when present, are confined to the basal layer. The major distinction between PUNLMP and urothelial papilloma is thickening of the urothelium in the former.

There is an orderly arrangement of urothelial cells and a lack of cytologic atypia.

PUNLMPs are not benign lesions, unlike papilloma, and although the incidence of recurrences and progression is low, close follow-up is recommended.

Most PUNLMPs correspond to "Papillary Urothelial Carcinoma, Grade 1" according to the previously used WHO Classification, 1973.

At higher magnification, urothelial lining is thickened. There is no cytologic atypia. Mitotic figures are absent.

See also

 low-grade papillary urothelial carcinoma

Open references

 Long-term outcome of primary Papillary Urothelial Neoplasm of Low Malignant Potential (PUNLMP) including PUNLMP with inverted growth.
Maxwell JP, Wang C, Wiebe N, Yilmaz A, Trpkov K. Diagn Pathol. 2015 Mar 13;10:3. doi : 10.1186/s13000-015-0234-z PMID: 25886613 (Free)