Omphalomesenteric duct cysts of the umbilical cord.

Three cases of omphalomesenteric (OM) duct cyst within the umbilical cord are presented and analyzed together with 6 previously reported cases. The embryology of the OM duct is reviewed, emphasizing those portions of the duct that may persist beyond early fetal life. Omphalomesenteric duct cysts are located at the proximal (fetal) end of the cord and range from 0.4-6.0 cm in diameter. They appear as cystically dilated "miniature" segments of the gastrointestinal tract and are lined by columnar epithelium resembling that of the gastric, small intestinal, or colonic mucosa; islands of pancreatic tissue may be associated with the cyst lining. The cysts have peripheral angiomatoid vascularity and the surface epithelium of the cord at one site tends to be hyperplastic. These lesions occur more often in males than in females and are unrelated to prematurity or to maternal age, race, or gravidity. They only rarely cause fetal morbidity or mortality but evidence is presented to suggest that they may on occasion be associated with potentially dangerous intraabdominal anomalies of the OM duct.