Bladder Cloacal Extrophy
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Anterior midline defect; Bladder exstrophy and epispadias complex; Cloacal exstrophy; Congenital malformation
Bladder exstrophy [BE] is a true congenital malformation characterized by a defect in the closure of the lower abdominal wall and the bladder with consequent eversion of the bladder mucosa through the ventral wall (Siffel et al. 2011).
BE affects about 2.07 per 100,000 births. It may also be associated with cloacal anomalies, other urinary tract and genital defects, particularly epispadias. Some authors consider cloacal exstrophy [CE] as the most severe end of a spectrum of malformations known as bladder exstrophy-epispadias complex (BEEC) or exstrophy-epispadias complex (EEC). CE is likely to result from an earlier development defect than BE.
BE results from a failure of mesenchymal migration between the ectodermal and endodermal layers of the cloacal membrane, normally occurring between the 6th and 7th week of development and which leads to failure of fusion of the midline structures below the umbilicus
It occurs with male predominance and male to female ratio of almost 2:1.
Eversion of the bladder mucosa through the lower ventral wall
BE is a life-threatening condition and surgical repair is strongly recommended early in life.
Bladder exstrophy is since long recognized as an important risk factor for malignancy development and may be associated with adenocarcinoma [>90%], squamous cell carcinoma [<10%], and urothelial carcinoma. Carcinomas with mixed histology are frequently reported (Rubenwolf et al. 2013). Mechanical irritation with subsequent chronic inflammation and metaplastic changes of untreated exstrophy has been suggested as predisposing factor to the development of malignant neoplasms. Data regarding the increased risk of adenocarcinoma and its association with intestinal metaplasia remains controversial, and alternative theories, such as a link to misplaced colonic epithelium or gene expression activation in von Brunn’s nests, have been proposed (Kathopoulis et al. 2016).
Contrary to what was previously thought, surgical correction of bladder exstrophy in the early period of life and even cystectomy does not reduce the risk of developing malignant neoplasm in this population which remains between 2% and 7%, similarly as has been previously reported in nonsurgically treated populations (Husmann and Rathbun 2008; Smeulders and Woodhouse 2001).
In a population of patients who benefited from reconstructive surgery and antibiotic treatment in early stages of life, a follow-up of 35 years, Smeulders and Woodhouse (2001) concluded that the risk of death from all causes was 60 times higher than that of a normal population aged less than 65 years and the risk of bladder cancer was 694 times that of an age-matched population. The incidence of neoplasia was estimated in 17.5% including bladder and colorectal carcinoma. The high risk of colorectal neoplasia is a consequence of a surgical reconstruction that creates a common urinary and fecal stream (e.g., ureterosigmoidostomy and vesico-colic anastomosis). Those patients have a 1726 times increased risk of adenocarcinoma of the colon and might benefit of regular screening with colonoscopy (Smeulders and Woodhouse 2001).
BE may be incomplete or complete and at birth the exposed urothelial mucosa has a normal appearance. However, urothelial mucosa abnormalities, such as ulceration and inflammation resulting from exposure to the external environment, can lead in a short period of time to an irregular, nodular, and thickened mucosa. Prominent lymphoid hyperplasia in the lamina propria may impart a finely nodular macroscopic appearance.
Nonsurgically treated BE cases are histologically described as having transitional epithelium covering the trigone, glandular epithelium in the midline, and squamous epithelium merging with the skin (Rubenwolf et al. 2013). Proliferative and metaplastic changes persist in surgically closed bladder in virtually all patients, including cystitis cystica and glandularis (up to 62%), intestinal metaplasia (up to 63%), and squamous metaplasia (Corica et al. 1997). Initially, the lamina propria is edematous and contains a variable amount of acute and chronic inflammation; eventually fibrosis can partially supersede those lesions (Rubenwolf et al. 2013).