Urinary System

Urinary Bladder - Inflammation

Narrative
Comment:
Inflammation is one of the most frequently diagnosed lesions of the urinary bladder. Inflammation may be acute, suppurative, chronic, chronic-active, or granulomatous, depending on the predominant cell type or cell response involved. In acute inflammation, the predominant infiltrating cell is the neutrophil, though fewer macrophages and lymphocytes may also be present. There may also be evidence of edema and hyperemia. The neutrophil is also the predominant cell type in suppurative inflammation; however, the neutrophils are aggregated, and many of them are degenerative (suppurative exudate). Lymphocytes predominate in chronic inflammation; lymphocytes also predominate in chronic-active inflammation, but there are also a significant number of neutrophils—both lesions contain macrophages. Diagnosis of granulomatous inflammation, another form of chronic inflammation, requires the presence of a significant number of aggregated, large, activated macrophages, epithelioid macrophages, or multinucleated giant cells.

Inflammatory cells can be seen anywhere in the bladder, including the lumen, mucosa, submucosa, and muscularis (Figure 1). Hemorrhage, necrosis, urothelial hyperplasia, and fibrosis may be evident, depending on the lesion (Figure 2). In most instances, inflammation arises from bacterial infections or the presence of calculi. Inflammation may also be a direct consequence of chemical administration.
Recommendations:
Inflammation should be diagnosed according to the cell response and the location within the bladder and should be given a severity grade. Hemorrhage, necrosis, urothelial hyperplasia, and fibrosis may be diagnosed separately if they constitute a significant component of the lesion.
References:

Frith CH. 1979. Morphologic classification of inflammatory, nonspecific, and proliferative lesions of the urinary bladder of mice. Invest Urol 16:435-444.

Abstract: http://www.ncbi.nlm.nih.gov/pubmed/571862

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.htm

Jokinen 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
  • Image of inflammation in the urinary bladder from a male F344/N rat in a chronic study

    Chronic-active inflammation involving the urothelium and subepithelial layers from a male F344/N rat in a chronic study.

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<p>Chronic-active inflammation involving the urothelium and subepithelial layers from a male F344/N rat in a chronic study.</p>

Chronic-active inflammation involving the urothelium and subepithelial layers from a male F344/N rat in a chronic study.
<p>Acute inflammation within the urothelium from a male F344/N rat in a chronic study.</p>

Acute inflammation within the urothelium from a male F344/N rat in a chronic study.

Authors

John Curtis Seely, DVM, DACVP
Senior Pathologist
Experimental Pathology Laboratories, Inc.
Research Triangle Park, NC

Abraham Nyska,  DVM, Diplomate ECVP, Fellow IATP
Expert in Toxicologic Pathology
Visiting Full Professor of Pathology
Sackler School of Medicine, Tel Aviv University
Timrat Israel

Reviewers

Samuel M Cohen, PHD, MD
Professor
Havlik-Wall Professor of Oncology
Director of Pathology Residency Program
Nebraska Medical Center
Omaha, NE

David E. Malarkey DVM, PhD, DACVP, FIATP
Head, National Toxicology Program Pathology Group
Cellular and Molecular Pathology Branch
Division of the National Toxicology Program
National Institute of Environmental Health Sciences
Research Triangle Park, NC