Complex colon duplication mimicking an obstructed, non-functioning kidney in a newborn with imperforate anus and spinal dysraphism.

Gastrointestinal (GI) duplications contain tissue resembling several portions of the GI tract and are associated with vertebral and genitourinary (GU) abnormalities [1-4]. We report a newborn with low, imperforate anus and lumbosacral dysraphism, who presented with a large cystic mass in the left renal fossa and pelvis. The flank mass (felt initially to be a dysplastic kidney and ureter) proved to be a complex GI duplication with histologic evidence of gastric, small bowel, and colonic mucosa, as well as respiratory epithelium and pancreatic tissue.