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Urothelial neoplasms-noninvasive

Papillary urothelial neoplasm of low malignant potential

Reviewer: Andreas Gaumann, M.D. (see Reviewers page)
Revised: 9 February 2013, last major update June 2010
Copyright: (c) 2003-2013, PathologyOutlines.com, Inc.


● Resembles the exophytic urothelial papilloma, but with increased cellular proliferation exceeding the thickness of normal urothelium; appears to lack the capacity to invade or metastasize
● ICD-O: 8130/1


● PUNLUMP: papillary urothelial neoplasm of low malignant potential


● Incidence of 3 cases / 100K individuals per year
● Male to female ratio 5:1, mean age 65 +/- 14 years
● In one US study, represented 25% of bladder tumors (Scand J Urol Nephrol 2008;42:237)
● In children, represent 50% of bladder tumors (BJU Int 2010;106:557)


● Preferred sites are the lateral posterior walls and ureteric orifices

Clinical features

● Presents with gross or microscopic hematuria
● May resemble “seaweed in ocean” at cystoscopy
● 1/3 recur, 5% as higher grade
● 10 year survival 95% or more
● Rarely associated with invasion or metastases
● Add to report, "Patients with these tumors are at risk of developing new bladder tumors ("recurrence"), usually of a similar histology. However, since these subsequent lesions occasionally manifest as urothelial carcinoma, follow up is warranted."
● Have lower MIB-1, p53 and mitotic counts than low grade papillary carcinomas, and higher median disease free survival (76 vs. 15 months, Am J Surg Pathol 2001;25:1528)

Prognostic factors

● Excellent prognosis when totally excised
● Tumors with focal high grade carcinoma act like high grade carcinomas
● Tumors with high Ki-67/MIB1 are more likely to recur (Cancer 2002;95:784)


● Resection, follow-up

Gross description

● 1-2 cm regular polypoid tumors

Micro description

● Orderly arrangement of cells within papillae with minimal architectural abnormalities and minimal nuclear atypia, regardless of cell thickness
● Thicker epithelium than papilloma, increase in nuclear size and hyperchromasia compared to papilloma
● Reduced cytoplasmic clearing compared to normal urothelium
● Neoplastic cells may extend down the stalk onto adjacent flat urothelium
● Mitotic figures, if present, are usually confined to basal layer

Micro images

Various images

Series of 17 images

PUNLMP (Fig A/B) compared to low grade papillary urothelial carcinoma (Fig C/D)

A: H&E; B: diffuse CD44+; C: superficial CK20+ in a few cells

Molecular / cytogenetics description

● No specific changes known

Differential diagnosis

Low grade papillary urothelial carcinoma: small cells more densely arranged on fibrovascular stalks, nuclear are rounder, more nuclear pleomorphism
Papilloma: no atypia
Polypoid / papillary cystitis: cystoscopic impression is inflammatory lesion, appears reactive at low power with inflamed background that is edematous or densely fibrous with predominantly simple, non-branching, broad-based fronds of relatively normal thickness (Am J Surg Pathol 2008;32:758)

End of Bladder > Urothelial neoplasms-noninvasive > Papillary urothelial neoplasm of low malignant potential

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