Cystitis and bladder metaplasias
- Lesion
Inflammation of the bladder is usually bacterial, but drugs, radiation, viruses and immune processes produce special forms and metaplasias.
What it is
Acute cystitis is mostly caused by gut bacteria, especially Escherichia coli, ascending through the urethra; women, catheters, outlet obstruction and diabetes favour it. Chemotherapy with cyclophosphamide, radiation and adenovirus infection give hemorrhagic cystitis. Interstitial cystitis (bladder pain syndrome) is chronic pain with mucosal ulcers in some patients. Malakoplakia reflects defective killing of bacteria by macrophages, polypoid cystitis follows catheter irritation, and chronic irritation causes cystitis glandularis and cystica, squamous metaplasia and nephrogenic metaplasia.
Structure
- Acute: red, edematous mucosa with neutrophils; may be hemorrhagic, suppurative or ulcerative.
- Chronic: thickened, red, friable mucosa with lymphocytes and fibrosis of the wall.
- Cystitis glandularis and cystica: nests of urothelium (Brunn nests) that become cystic or glandular; common and reactive.
- Squamous metaplasia: keratinizing squamous epithelium after chronic irritation; nephrogenic metaplasia: small tubules after injury, mimicking adenocarcinoma.
- Malakoplakia: sheets of foamy macrophages (von Hansemann cells) with Michaelis-Gutmann bodies.
Forms of cystitis
| Form | Cause | Key feature |
|---|---|---|
| Bacterial cystitis | E. coli and other gut bacteria | Dysuria, frequency, pyuria |
| Hemorrhagic cystitis | Cyclophosphamide, radiation, adenovirus | Blood in the urine, hemorrhagic mucosa |
| Interstitial cystitis | Unknown, chronic | Pain relieved by voiding; Hunner ulcers in some |
| Malakoplakia | Defective macrophage killing of bacteria (often E. coli) | Yellow plaques, Michaelis-Gutmann bodies |
| Polypoid cystitis | Catheters, irritation | Edematous polypoid mucosa that can mimic papillary tumour |
Clinical notes
- Classic triad of cystitis: frequency, lower abdominal pain and dysuria.
- Asymptomatic bacteriuria needs treatment only in pregnancy and before urologic procedures.
Test yourself
Think of the answer, then tap the question to see it.
Which drug is classically associated with hemorrhagic cystitis?
Cyclophosphamide, through its metabolite acrolein.
What are Michaelis-Gutmann bodies?
Laminated, mineralized inclusions in macrophages, diagnostic of malakoplakia.
Which parasite causes chronic cystitis that predisposes to squamous cell carcinoma?
Schistosoma haematobium.
Elsewhere in DurgiPedia
Connections
Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given.
Sources: Acute Cystitis (StatPearls (NCBI Bookshelf), 2024); Interstitial cystitis: MedlinePlus Medical Encyclopedia (MedlinePlus, US National Library of Medicine, 2025).
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Representative model, for educational purposes only.