Gastrointestinal duplications are rare congenital lesions that can develop anywhere along the alimentary tract and may present in the newborn period as an abdominal mass. They are differentiated from other intraabdominal cystic lesions by the presence of a normal gastrointestinal mucosal lining. Multiple theories have been proposed to account for these lesions; however, no single theory adequately explains all the known duplications. They are most frequently single, tubular, or cystic and located on the mesenteric side of the native alimentary tract structure. Symptoms often are related to the location of the duplication; oral and esophageal lesions can create respiratory difficulties, whereas lower gastrointestinal lesions may cause nausea, vomiting, bleeding, perforation, or obstruction. Treatment is resection with care taken to protect the common blood supply of the native structures. Occasionally, a partial resection with mucosal excision is required to preserve intestinal mucosa.

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The effect of direct intestinal overexpression of epidermal growth factor (EGF) on postresection adaptation has been investigated by the production of transgenic mouse lines. A murine pro-EGF cDNA construct was produced, and expression of the EGF construct was targeted to the small intestine with the use of the rat intestinal fatty acid-binding protein promoter. An approximately twofold increase in intestinal EGF mRNA and protein was detected in heterozygous mice. No changes in serum EGF levels were noted. Except for a slightly shortened small intestine, no other abnormal phenotype was observed. Intestinal adaptation (increases in body weight, DNA, protein content, villus height, and crypt depth) was markedly enhanced after a 50% proximal small bowel resection in transgenic mice compared with nontransgenic littermates. This transgenic mouse model permits the study of intestinal adaptation and other effects of EGF in the small intestine in a more physiological and directed manner than has been previously possible. These results endorse a direct autocrine/paracrine mechanism for EGF on enterocytes as a means to enhance adaptation.

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