Keratinising squamous metaplasia of the urinary bladder

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Keratinising squamous metaplasia of the urinary bladder
Diagnosis in short

Keratinizing squamous metaplasia of the bladder. H&E stain. (WC/Nephron)

LM squamous epithelium with hyperkeratosis or parakeratosis, negative for atypia
LM DDx squamous dysplasia of the metaplastic epithelium, squamous cell carcinoma of the urinary bladder, metastatic squamous cell carcinoma, urothelial carcinoma with squamous metaplasia or squamous differentiation
Site urinary bladder

Clinical history usually males (males:females = 4:1)
Prevalence rare
Prognosis benign, increased risk of malignancy
Treatment clinical follow-up

Keratinising squamous metaplasia of the urinary bladder is a rare benign change of the urinary bladder associated with an increased risk of malignancy;[1] however, it is not considered a pre-malignant condition.[2][3]

Urinary bladder with squamous metaplasia and squamous metaplasia of the urinary bladder redirect to this article.


  • Rare.[3]
  • Large age range (13-80 years).[1]
  • Predominantly males - almost 4:1 (27 males:7 females in one series[1]).


  • Follow-up is recommended.[3][4]


  • ‡ Non-keratinizing squamous metaplasia can be considered normal and is relatively common in the trigone region of the bladder in women.[citation needed]



  • Squamous epithelium with hyperkeratosis or parakeratosis.
  • Negative for significant nuclear atypia.


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Urinary Bladder Lesion, Biopsy:
- Extensive keratinizing squamous metaplasia with degenerative changes and acute 
  and chronic inflammation.
- NEGATIVE for dysplasia and NEGATIVE for malignancy.

Regular follow-up is recommended.[1,2]

1. Urol Int 81 (3): 247-51. doi:10.1159/000151398. PMID 18931537.
2. Urologia 87 (2): 97–100. doi:10.1177/0391560318810197. PMID 30509153.

See also


  1. 1.0 1.1 1.2 Khan, MS.; Thornhill, JA.; Gaffney, E.; Loftus, B.; Butler, MR. (Nov 2002). "Keratinising squamous metaplasia of the bladder: natural history and rationalization of management based on review of 54 years experience.". Eur Urol 42 (5): 469-74. PMID 12429156.
  2. Kvist, E.; Sjølin, KE.; Laursen, H.; Orntoft, TF.; Sturmer, MA. (Jul 1992). "Squamous cell metaplasia of the bladder urothelium. A retrospective study of 36 patients.". APMIS 100 (7): 650-4. PMID 1379440.
  3. 3.0 3.1 3.2 Ahmad, I.; Barnetson, RJ.; Krishna, NS. (2008). "Keratinizing squamous metaplasia of the bladder: a review.". Urol Int 81 (3): 247-51. doi:10.1159/000151398. PMID 18931537.
  4. Benelli A, Varca V, Vaccaro C, Guzzo S, Nicola M, Onorati M, Gregori A, Di Nuovo F (May 2020). "Keratinizing squamous metaplasia of the bladder: Our experience and current approaches". Urologia 87 (2): 97–100. doi:10.1177/0391560318810197. PMID 30509153.