Case of the Month: January, 2011 Page 5
- On VCUG, bladder diverticula decrease in size with bladder contraction. False.
- Congenital bladder diverticula are strongly associated with vesicoureteral reflux. True.
- Congenital bladder diverticula are more common in females. False.
- “Bladder ears” are a type of acquired bladder diverticula. False.
Discussion: Bladder Diverticula
Bladder diverticula are outpouchings of the urothelial lining that project through the muscular wall of the bladder. They are caused by congenital or acquired defects of the bladder wall. Most are small and asymptomatic, however, they may be associated with inflammation, calculi, infection, reflux, obstruction, urinary retention, and malignancy.
On dynamic imaging, such as VCUG, diverticula enlarge during voiding due to thin or absent muscle layer. Physiologically, voiding will usually accentuate obstructive symptoms produced by diverticula.
Diverticula can be either congenital or acquired. Most are of the acquired type. They are often found in older men due to bladder outlet obstruction from BPH. Less frequently they result from prostatitis, prostate carcinoma or urethral pathology that results in bladder outlet obstruction.
Congenital diverticula are rare and seen almost exclusively in males. The wall of the diverticulum is thin and contains muscle, adventitia and bladder mucosa. Congenital diverticula occur most commonly adjacent to the ureteric orifice, and are called Hutch diverticula. These diverticula have an extremely high association with vesicoureteral reflux, but may also cause ureteral obstruction. Some congenital diverticula are associated with bladder outlet obstruction, such as that seen in posterior urethral valves or Prune Belly syndrome. They also may be seen in patients with neurogenic bladder in conditions such as myelomeningocele. These diverticula, like acquired diverticula do not contain a muscle layer.
In contrast to congenital diverticula, “bladder ears” are herniations of the bladder wall into inguinal hernias. They contract with bladder contraction and are located anteriorly. They frequently disappear with aging. Their diagnosis is critical in planning hernia repair in order to avoid bladder injury.
Urinary stasis in bladder diverticula leads to chronic inflammation , infection and often stone formation. Dysplasia, leukoplakia, and squamous cell metaplasia is present in approximately 80% of all diverticula. These histologic abnormalities may precede the development of neoplasia. Transitional cell carcinoma is most common (75%), followed by squamous cell carcinoma (15%) and adenocarcinoma (2%). About 2-7% of patients with a bladder diverticulum will develop a carcinoma within it. Generally, they have a poorer prognosis than bladder carcinoma arising in the bladder itself due to thin or absent muscle layer resulting in early spread of disease.
- Maheshwari Praveen R, Nagar Arpit M, Morani Ajaykumar, Prasad Shashank P, Kamat Neemish. Carcinoma Arising in a Urinary Bladder Diverticulum : Images in Radiology. Bhj.org.
- Lam KY, Ma L, Nicholls J. Adenocarcinoma arising in the diverticulum of the urinary bladder. Pathology 1992; 24 (1) : 40-2.
- Joanna J. Seibert, Charles A. James. Pediatric Radiology Casebase.
- Blane C, Zerin JM, Bloom DA. Bladder diverticula in children. Radiology. 1994 Mar;190(3):695-7.
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