Fetus in fetu: a case with complete umbilical cord and fetal sac

The authors present a retroperitoneal fetus in fetus in a 3-month-old girl. A 15-cm cystic mass with a monstrous fetuslike structure surrounded by a complete sac containing serous fluid was removed from the left retroperitoneal space. The draining vessel of the cystic mass was connected to the right renal vein of the host. The included fetus weighed 380 g. It had a well-developed umbilical cord, four extremities, head, buttock, and vertebral bodies with a meningomyelocele. The thoracic cavity of the included fetus had only a saclike foregut structure, but the abdominal cavity revealed a full length of intestine with a Meckel diverticulum, bilateral ovaries, urinary bladder, and cloaca with external opening. The cephalic end was composed of well-developed tooth germs, tongue and buccopharynx, mandible, maxilla, sphenoid bone, and salivary glands. Chromosomal study showed 46,XX with a normal G banding pattern. We report this case as an example of fetus in fetu with a complete umbilical cord and fetal membrane.