Urinary System
Urinary Bladder - Metaplasia
Narrative
Comment:
Metaplasia of the urothelium reflects the potential of the urothelium to undergo a metaplastic change under a variety of conditions. Squamous metaplasia, with or without keratinization, is the most common variant observed (Figure 1, Figure 2, and Figure 3). Mucinous, glandular, or mixtures of metaplastic lesions are less commonly observed (Figure 4).
Recommendations:
Urothelial metaplasia and, in particular, the type of metaplasia should be diagnosed and given a severity grade when it becomes a major part of a lesion, for instance, in association with inflammation or hyperplasia. Small or focal lesions, when part of a primary lesion such as chronic inflammation and/or hyperplasia, should not be diagnosed separately.
References:
Gaillard ET. 1999. Ureter, urinary bladder and urethra. In: Pathology of the Mouse: Reference and Atlas (Maronpot RR, Boorman GA Gaul BW, eds). Cache River Press, Vienna, IL, 235-258.
Abstract: http://www.cacheriverpress.com/books/pathmouse.htmJokinen MP. 1990. Urinary bladder, ureter, and urethra. In: Pathology of the Fischer Rat: Reference and Atlas (Boorman GA, Eustis SL, Elwell MR, Montgomery CA, MacKenzie WF, eds). Academic Press, San Diego, 109-126.
Abstract: http://www.ncbi.nlm.nih.gov/nlmcatalog/9002563
Squamous metaplasia and keratinization from a female F344/N rat in a 40-week interim study.
All Images
Diffuse squamous metaplasia and keratinization of hyperplastic urothelium from a female F344/N rat in a subchronic interim study.
Squamous metaplasia and keratinization from a female F344/N rat in a 40-week interim study.
Squamous metaplasia with and without keratinization, from a female F344/N rat in a subchronic interim study.
Mucinous metaplasia (arrows) characterized by mucinous cells in areas of urothelial hyperplasia, from a female F344/N rat in a chronic study.