Urothelial neoplasms-noninvasive
Squamous papilloma

Author: Nat Pernick, M.D. (see Authors page)

Revised: 9 December 2016, last major update November 2016

Copyright: (c) 2016,, Inc.

PubMed Search: Squamous papilloma bladder [title]

Page views in 2019 to date: 72
Cite this page: Squamous papilloma. website. Accessed June 17th, 2019.
Definition / general
  • PUNLUMP: papillary urothelial neoplasm of low malignant potential
  • 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)
Gross description
  • 1-2 cm regular polypoid tumors
Microscopic (histologic) 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
Microscopic (histologic) images

Images hosted on other servers:

Intermediate magnification

Low magnification


Urothelial thickening

Homogenous monotonous appearance

Orderly arrangement of urothelial cells

Urothelial lining is thickened

Examples of papillary tumor of low malignant potential

H&E, CD44+, CK20+

Images hosted on Flickr:


Molecular / cytogenetics description
  • No specific changes known
Differential diagnosis
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