[Fetus in fetu: a case report of an extremely rare cause of abdominal tumors in the infant].

Fetus in fetu is an extremely uncommon cause of an abdominal mass in the neonate. A 6-week-old female was brought to our hospital because of an upper abdominal mass. A plain x-ray demonstrated a mass of structured bones that suggested a teratoma or fetus in fetu. At operation a 20 cm mass was found in the mesocolon covered by a membrane. The mass corresponded to a fetus in fetu connected by an umbilical-like cord to the host in the depth of the radix mesocoli. The fetus in fetu weighed 150 g and had severe malformations, such as internal hydrocephalus, a left side anotia, a descended right ear, anophthalmia, a right-sided amelia, a micromelia on the left side with 4 fingers, a sympus with 5 and 7 toes on the left and right side, respectively. There was also an almost complete aplasia of the internal organs with some remnants of intestine near the umbilical cord.