Allantoic cyst and persistent urachal-allantoic communication: a rare umbilical anomaly.

True cysts of the umbilical cord are distinctly rare. A cyst lined by uroepithelium is described in a newborn in whom the cyst communicated freely with a patent urachal system. It is assumed that this most likely represents a remnant cyst of the allantois--an anomaly not described previously.