AUTHOR AND EDITOR INFORMATION
Section 1 of 11  
Author: Scott Rutchik, MD, Assistant Professor, Department of Surgery, Division of Urology, University of Connecticut School of Medicine
Scott Rutchik is a member of the following medical societies: American Urological Association
Editors: Leonard Gabriel Gomella, MD, FACS, Director of Urologic Oncology, Bernard W Godwin Associate Professor of Prostate Cancer, Department of Urology, Kimmel Cancer Center, Thomas Jefferson University; Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine; J Stuart Wolf, Jr, MD, FACS, David A Bloom Professor of Urology, Director, Division of Minimally Invasive Urology, Department of Urology, University of Michigan Medical Center; Stephen W Leslie, MD, FACS, Founder and Medical Director of the Lorain Kidney Stone Research Center, Clinical Assistant Professor, Department of Urology, Medical College of Ohio
Author and Editor Disclosure
Synonyms and related keywords:
trigonal squamous metaplasia, pseudomembranous trigonitis, bladder leukoplakia, bladder cancer, cystitis trigoni, true trigonal membrane, trigonal nonkeratinizing squamous metaplasia, trigone leukoplakia, trigonal leukoplakia, squamous trigonal metaplasia, bladder disorder, trigone disorder
Background
Trigonitis describes the apparent squamous metaplastic changes that occur in the trigone of the bladder (see Image 1). These changes are much more common in adult females. Heymann first described the lesion in 1905 as cystitis trigoni. Subsequently, Cifuentes described the condition as a true trigonal membrane.
Pathophysiology
The trigone of the bladder (as well as the ureters) are embryologically derived from the mesonephric duct primordia. Normally, this area of the bladder is covered in relatively impermeable transitional epithelium.
In young females, there may be an overgrowth of squamous vaginal-type epithelium, a condition often referred to as trigonitis. In this setting, trigonitis is incorrect terminology because no associated inflammatory reaction exists. This condition is referred to more properly as trigonal nonkeratinizing squamous metaplasia.
Mortality/Morbidity
This condition has minimal morbidity or mortality unless it evolves into frank squamous carcinoma.
Sex
- Squamous metaplastic changes of the trigone are observed in as many as 40% of adult women.
- Similar lesions are much less common in men, with an observed frequency of only 5%.
Age
Squamous metaplasia of the trigone occurs almost exclusively in women of childbearing age. It is almost nonexistent in children.
Physical
- Simple physical examination probably will not identify this lesion.
- The diagnosis is confirmed by cystoscopic examination of a white patch of tissue in the bladder trigone.
Causes
- The causes of squamous trigonal metaplasia are unclear.
- In the classic nonkeratinizing lesion observed in younger females, the etiology may be secondary to vaginal epithelial overgrowth of the trigone.
- The keratinizing variant frequently is associated with chronic irritation secondary to indwelling instrumentation, calculi, or, in endemic areas, Schistosoma haematobium infection.
Urinary Tract Infection, Females
Other Problems to be Considered
Malakoplakia of the bladder
Squamous cell carcinoma of the bladder
Leukoplakia of the bladder
Lab Studies
- If the patient has irritative voiding symptomatology, urinalysis with cultures and sensitivities (in select cases) may be conducted to exclude infection.
Imaging Studies
- Imaging studies are not normally useful in diagnosing so-called trigonitis. However, Sugaya et al reported that ultrasonographic examination of the bladder in patients with trigonitis may reveal a thickening of the bladder-neck mucosa.
Procedures
- Cystoscopy with bladder biopsy is rarely warranted in young females but should be performed in males with this lesion or in females with hematuria.
Histologic Findings
Squamous metaplasia of the trigone is composed of stratified squamous epithelium that often contains abundant glycogen. If the lesion is benign, there is usually little atypia. The basal cell layer has prominent nuclei with condensed chromatin and nucleoli. The surface cells are linked by desmosomes and are longitudinally oriented. Jost et al demonstrated a mitotic index of these lesions of 0.17%, larger than the expected value of 0%.
Keratinization is a somewhat more ominous sign because these lesions are more commonly associated with frank carcinoma. Such lesions usually are referred to as leukoplakia. Benson et al determined that 21% of patients with urothelial leukoplakia progressed to malignancy.
Medical Care
In young females, this lesion does not warrant treatment, since it is essentially normal tissue.
Surgical Care
- Bladder biopsy may be performed cystoscopically, along with fulguration.
- Generally, the lesion is diffuse, and complete resection is not performed, even in higher-risk patients.
Consultations
A urologist may be consulted.
This condition does not require drug treatment.
Further Inpatient Care
- In higher-risk patients with biopsy-proven keratinizing metaplasia, perform annual cystoscopy and urinary cytologic examinations.
Deterrence/Prevention
- Chronic indwelling instrumentation of the bladder should be discouraged if better alternatives for bladder drainage are feasible.
Complications
- Progression to frank squamous cell carcinoma of the bladder may occur in patients with keratinizing squamous metaplasia of the trigone.
Prognosis
- The prognosis for the nonkeratinizing variant is excellent. This variant is not likely to represent a pathologic state.
- The keratinizing lesion also is benign, but it should be checked at regular intervals.
Patient Education
Medical/Legal Pitfalls
- Failure to differentiate malignancy from the benign disease is possible, particularly if an inadequate tissue sample was taken during biopsy in at-risk patients.
- Benson RC Jr, Swanson SK, Farrow GM. Relationship of leukoplakia to urothelial malignancy. J Urol. Mar 1984;131(3):507-11. [Medline].
- Cifuentes L. Epithelium of vaginal type in the female trigone: the clinical problem of trigonitis. J Urol. 1947;57:1028-37.
- Henry L, Fox M. Histological findings in pseudomembranous trigonitis. J Clin Pathol. Oct 1971;24(7):605-8. [Medline].
- Heymann A. Die cystitis trigoni der frau. Zentralbl Kr Harn Sex. 1905;16:422-33.
- Jost SP, Gosling JA, Dixon JS. The fine structure of human pseudomembranous trigonitis. Br J Urol. Nov 1989;64(5):472-7. [Medline].
- Locke JR, Hill DE, Walzer Y. Incidence of squamous cell carcinoma in patients with long-term catheter drainage. J Urol. Jun 1985;133(6):1034-5. [Medline].
- Long ED, Shepherd RT. The incidence and significance of vaginal metaplasia of the bladder trigone in adult women. Br J Urol. Apr 1983;55(2):189-94. [Medline].
- Mueller SC, Thueroff JW, Rumpelt HJ. Urothelial leukoplakia: new aspects of etiology and therapy. J Urol. May 1987;137(5):979-83. [Medline].
- Murphy WM. Diseases of the urinary bladder, urethra, ureters, and renal pelves: squamous metaplasia. Urological Pathology. 1997;60-2.
- Sugaya K, Nishijima S, Oda M, et al. Transabdominal vesical sonography of urethral syndrome and stress incontinence. Int J Urol. Jan 2003;10(1):36-42. [Medline].
- Tyler DE. Stratified squamous epithelium in the vesicle trigone and urethra: findings correlated with menstrual cycle and age. Am J Anat. 1962;111:319-25.
Trigonitis excerpt Article Last Updated: Apr 26, 2006
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