Etiology and Epidemiology
Inflammation of the urinary bladder is the most significant problem among all pathologies of this organ. From an epidemiological standpoint, this condition has a distinct pattern: it is most frequently diagnosed in young women of reproductive age. However, in older age, gender differences disappear, and the inflammation affects individuals of both sexes equally.
In the vast majority of cases, the etiology is associated with infectious agents. The leading role is played by intestinal flora: E. coli, Proteus, Klebsiella, and Enterobacter. Viruses (specifically adenovirus), as well as Chlamydia and Mycoplasma, initiate the inflammatory process much less frequently. Tuberculous cystitis deserves special attention, as in clinical practice it almost always leads to renal tuberculosis.
In addition to classic infections, there are iatrogenic (non-infectious) causes:
- Radiation cystitis: occurs as a direct consequence of irradiation of the bladder area.
- Hemorrhagic cystitis: develops secondary to the administration of potent cytotoxic drugs (cyclophosphamide, myelosan, methotrexate, ifosfamide, cisplatin).
Pathogenesis and morphology of acute forms
The main danger of infectious bladder involvement lies in the risk of ascending infection. Microorganisms can retrogradely enter the pelvicalyceal system, causing a severe complication—bacterial pyelonephritis. Inflammatory diseases of the bladder themselves are practically never fatal (unlike tumors of the organ, which are a major cause of mortality).
Macroscopically and microscopically, the acute process in most cases presents as non-specific inflammation. Marked mucosal hyperemia and accumulation of inflammatory exudate are observed. Depending on the nature of the exudate, the following morphological forms are distinguished:
- Hemorrhagic cystitis: characterized by a hemorrhagic component in the exudate. This form is typical of radiation therapy, chemotherapy, and adenoviral infection.
- Phlegmonous cystitis: manifests as an accumulation of purulent exudate.
- Ulcerative cystitis: develops under the influence of pyogenic flora, leading to ulceration of large areas or even the entire mucosal surface.
Chronicity and specific forms
If the infection persists for a long time, the process transitions into a chronic stage. The main morphological difference between chronic and acute cystitis is the change in the nature of the inflammatory infiltrate. A prolonged course inevitably leads to structural remodeling: fibrotic thickening of the lamina propria of the mucosa occurs. As a result, the bladder wall thickens and loses its elasticity.
In pathological anatomy, two specific histological forms of chronic inflammation are distinguished:
- Follicular cystitis: a form characterized by the accumulation of lymphocytes in the mucosa and underlying layers with the formation of lymphoid follicles.
- Eosinophilic cystitis: characterized by infiltration of the submucosa by eosinophils. This process is accompanied by the development of fibrosis and the appearance of giant cells in the tissues.
Briefly: answers to topical questions
What morphological forms of acute cystitis are distinguished depending on the nature of the exudate?
Depending on the nature of the exudate and the characteristics of the tissue damage, several morphological forms of acute cystitis are distinguished.
- Hemorrhagic cystitis — characterized by a hemorrhagic component in the inflammatory exudate.
- Phlegmonous cystitis — manifests as an accumulation of purulent exudate.
- Ulcerative cystitis — accompanied by ulceration of large areas or the entire mucosa due to pyogenic flora.
In most cases, non-specific inflammation is observed with mucosal hyperemia and inflammatory exudate.
What specific histological forms of chronic cystitis are distinguished in pathological anatomy?
Pathological anatomy distinguishes two specific histological forms of chronic cystitis.
- Follicular cystitis — a form of chronic inflammation characterized by the accumulation of lymphocytes into lymphoid follicles within the mucosa and underlying layers.
- Eosinophilic cystitis — manifests as infiltration of the submucosa by eosinophils, development of fibrosis, and the appearance of giant cells.
What compensatory-adaptive changes of the urothelium occur in prolonged chronic cystitis?
Metaplasia may develop in the urothelium during prolonged chronic cystitis.
- Squamous metaplasia of the urothelium — focal replacement of the normal transitional epithelium of the bladder with non-keratinizing stratified squamous epithelium.
- In older terminology, this process was called leukoplakia of the urinary bladder.
Metaplasia is a stable, usually reversible replacement of one differentiated tissue type by another within the same histogenetic series. It is considered a background condition that, if the chronic damaging factor persists, increases the risk of subsequent dysplasia and malignant transformation.
What are the microscopic features of phlegmonous cystitis?
The microscopic feature of phlegmonous cystitis is the accumulation of purulent exudate. Phlegmon is generally defined as diffuse purulent inflammation with infiltration and dissection of tissues by purulent exudate.
What is the pathogenesis and morphological manifestations of radiation cystitis?
Radiation cystitis is an iatrogenic non-infectious form of cystitis that occurs as a consequence of irradiation of the bladder area. Radiation therapy is also listed among the causes of hemorrhagic cystitis. Hemorrhagic cystitis is characterized by a hemorrhagic component in the inflammatory exudate. In most cases, cystitis presents as non-specific inflammation; microscopic findings include mucosal hyperemia and inflammatory exudate.
To easily remember the main bacterial pathogens from the intestinal flora, use the acronym PEEK: Proteus, E. coli, Enterobacter, Klebsiella.
Class and exam questions
How does chronic cystitis morphologically differ from acute cystitis?
The main difference lies in the nature of the inflammatory infiltrate. In the chronic course, fibrosis of the lamina propria of the mucosa also develops, leading to wall thickening and loss of its elasticity.
Which drugs can cause hemorrhagic cystitis?
The development of iatrogenic hemorrhagic inflammation is often caused by the administration of cytotoxic drugs: cyclophosphamide, myelosan, methotrexate, ifosfamide, and cisplatin.
What is the histological feature of follicular cystitis?
This is a specific form of chronic inflammation in which lymphocytes accumulate in the mucosa and underlying layers, forming prominent lymphoid follicles.
What is the most frequent complication of infectious cystitis?
The most severe and frequent complication is bacterial pyelonephritis, which occurs due to the retrograde migration of microorganisms from the bladder into the kidneys.
What else to study on this topic
- Pathogenesis of retrograde renal infection in cystitis
- Mechanisms of mucosal damage in radiation and chemotherapy
- Morphological features of eosinophilic cystitis on microscopic specimens
- Association of tuberculous cystitis with renal tuberculosis
- Bladder tumors as a cause of morbidity and mortality
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