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Bladder

Congenital anomalies

Exstrophy


Reviewer: Alcides Chaux, M.D., Johns Hopkins University School of Medicine (see Reviewers page)
Revised: 19 April 2011, last major update April 2011
Copyright: (c) 2003-2011, PathologyOutlines.com, Inc.

Definition
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● Bladder mucosa is exposed to the surface exterior through a defect in the anterior abdominal wall

Terminology
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● Also called classic bladder exstrophy
● Part of exstrophy-epispadias complex (bladder exstrophy, epispadias, failure of labia fusion, lack of symphysis pubis fusion)

Epidemiology
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● Prevalence at birth is 1 per 50,000-100,000; male predominance up to 5:1
● May be associated with maternal tobacco use (J Urol 2008;179:1539)
● High concordance in identical and non-identical twins
● Documented cases of family clusters

Etiology
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● Developmental failure in lower abdominal wall or anterior wall of bladder due to failure of cloacal membrane to properly differentiate
● Persistence or overgrowth of cloacal membrane on lower anterior abdominal area may prevent normal mesenchymal ingrowth, which causes divergence of lower abdominal muscular structures, and forces the genital ridges to fuse caudal to the cloacal membrane (J R Soc Med 1996;89:39P)
● The stage of ingrowth of the urorectal septum at the time of rupture determines whether one will produce an exstrophic urinary tract alone (classic bladder exstrophy or epispadias) or cloacal exstrophy with the hindgut interposed between the hemibladders

Clinical features
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● Usually diagnosed with prenatal scans
● Urine drips from ureteric orifices onto bladder surface (Orphanet J Rare Dis 2009 Oct 30;4:23)
● Bladder mucosa is red at birth, and mucosal polyps may be seen
● If closure is delayed, may have inflammatory changes of whitish coating, ulcerations and hyperplastic formations
● Thin skin stripes mark transition between normal skin and squamous metaplastic area
● Most patients have bilateral inguinal hernias
● Male newborns have open (epispadic) urethral plate that covers whole dorsum of penis from open bladder to glandular grove
● Female newborns have completely split clitoris next to the open urethral plate; also narrow vaginal opening anterior to a shortened perineum

Treatment
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● Surgical correction with several procedures over time (Johns Hopkins), usually beginning in first week of life
● Rarely, adults present to physicians with exstrophy (Indian J Urol 2008;24:164)
● Even in surgically treated patients, bladder mucosa reverts to normal in only 25% of cases

Clinical images
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Exstrophy in male infants


Diagrams of exstrophy

Micro description
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● Acute and chronic inflammation; lamina propria fibrosis in practically all cases at any age
● Metaplastic changes are very common and include squamous and glandular metaplasia
● Evidence of mucosal proliferation (von Brunnís nests, cystitis cystica, and cystitis glandularis) in most cases
● Associated with adenocarcinoma (<10% of exstrophied bladders), squamous cell carcinoma (~7% of patients) or very rarely urothelial (transitional) carcinoma

Additional references
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eMedicine

End of Bladder > Congenital anomalies > Exstrophy


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