Anal canal duplication: a retrospective analysis of 12 cases from two European pediatric surgical departments

Anal canal duplication (ACD) represents an extremely rare intestinal congenital anomaly of unknown origin. Usually evidenced within 2 years of age, nearly 45% of reported cases present associated malformations such as presacral mass, anorectal malformation (ARM) and genitourinary anomalies. The confirmative diagnosis is histopathological, with evidence of an anal mucosal lining (squamous +/- transitional epithelium), surrounded from a smooth muscle coat and anal glands. We review a conjoined experience from two European pediatric surgical departments. From 1970 to 2005, 12 patients were observed, seven in Pescara, Italy (1997-2005), five in Barcelona, Spain (1970-2004) - mean age at diagnosis 17.8 months, range 0-60; M:F = 1:11. Clinical presentation, diagnostic-surgical approach, and complications were reviewed. According to clinical presentation, patients could be divided in three age groups: asymptomatic (mean age 4.8 months, six patients - one with an associated complex genitourinary malformation, one with a presacral mature teratoma, one with ACD evidenced hysthologically on a retroanal mass removed during the correction of an ARM), mildly symptomatic - constipation, mucous discharge (mean age 29.2 months, four patients - one with associated presacral ependymoma and intestinal neuronal dysplasia type B, one with presacral mass) and complicated - perineal abscess, recurrent fistula (mean age 34 months, two patients). In 11 cases a perianal orifice was evident (ten posteriorly located). The pelvic-MRI was the preferred diagnostic tool in Pescara (5/7, with presacral mass in two patients), fistulography in Barcelona (5/5), where one presacral mass was discovered intraoperatively. Eleven patients underwent surgical removal of the ACD (five perineal approach, five posterior sagittal approach, and one PSARP). Histopathological findings confirmed the diagnosis in operated cases (11). The parents of the male patient denied the consent to surgical treatment. The only major post-operative complication was a sphincteric insufficiency (one case), surgically treated. When facing a perianal orifice, attention should be paid to ACD, particularly in female patients with coexistent genitourinary or intestinal malformations. Pelvic US and MRI are the gold standard to evidence the not rarely associated presacral mass. Surgical early removal (mucosectomy or perineal/posterior sagittal approach, depending on length of ACD and associated presacral mass) is warranted, also in asymptomatic patients, because of the risk of inflammatory complications and cancer (the latter reported in literature in adults).