Bladder
Urothelial neoplasms-noninvasive
Urothelial papilloma

Author: Monika Roychowdhury, M.D. (see Authors page)

Revised: 13 July 2016, last major update December 2014

Copyright: (c) 2003-2016, PathologyOutlines.com, Inc.

PubMed Search: Urothelial papilloma[title]
Cite this page: Urothelial Papilloma. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/bladderpapilloma.html. Accessed December 4th, 2016.
Definition / General
  • Discrete papillary growth with a central fibrovascular core lined by urothelium of normal thickness and cytology
Epidemiology
  • Uncommon if use restrictive diagnostic criteria (less than 1% of bladder tumors)
  • Tends to occur in younger patients (mean age, 46 years; range 22-89 years) and may occur in children ( Cancer 1999;86:2098)
  • Risk factors similar to those of urothelial neoplasm (cigarette smoking and occupational exposure to aromatic amines, Histopathology 2008;53:621)
Sites
  • Most common in posterior or lateral walls (close to ureteric orifices) and urethra
Clinical Features
  • Hematuria
  • Either de novo (most common) or secondary to known urothelial carcinoma
  • In de novo cases, mean age 46-58 years, 2/3 male, occasional recurrence, occasional progression to papillary urothelial carcinoma
  • In secondary cases, mean age 66 years, may recur
  • Recommended to avoid labeling these patients as having cancer (Am J Surg Pathol 2004;28:1615)
  • Benign behavior; may recur but only rarely progresses
Prognostic Factors
  • Rare cases of progression have been described in association with immunosuppressive therapy
Treatment
  • Excision and follow-up
Gross Description
  • Soft, pink, small isolated growth with delicate papillary structures, usually pedunculated, mean 3 mm
Micro Description
  • Discrete papillary fronds with occasional branching but without fusion; these fronds are covered by normal urothelium
  • Papillae appear to float above urothelial surface due to sectioning of branching papillae
  • Papillae usually small with scant stroma and slender fibrovascular cores
  • May have large papillae with marked stromal edema or cystitis cystica-like invaginations
  • Lined by normal appearing urothelium with prominent umbrella cells, normal polarity, variable dilated lymphatics within fibrovascular fronds, vacuolization; no hyperplasia, no dysplasia, no fusion of adjacent fronds, no necrosis, no/minimal mitotic figures (if present, they are in basal layers)
  • Rarely urothelial papilloma can extensively involve the mucosa, a phenomenon referred to as diffuse papillomatosis (Eur Urol 2004;46:170)
Micro Images

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Papilloma with delicate fibrovascular core, normal urothelium and cystoplasmic vacuoles

Positive Stains
  • CK20 (limited to superficial/umbrella cells as in normal urothelium)
Negative Stains
  • p53
Molecular / Cytogenetics Description
Differential Diagnosis
  • Papillary urothelial neoplasm of low malignant potential: longer and thicker papillae with hyperplasia, less prominent umbrella cells
  • Papillary urothelial hyperplasia: >7 cells thick, undulating pattern of thin mucosal papillary folds of varying heights, no discrete fibrovascular cores, vascularity present at base of urothelial proliferation