Foetus-in-fetu an Unusual Cause of Abdominal Mass in the Newborn

Abstract

Foetus-in-fetu (FIF) is a rare congenital condition in which a vertebrate foetus is incorporated within its twin. The authors report the case of a newborn girl with prenatal ultrasonographic diagnosis of an intra-abdominal mass. Abdominal ultrasonography and computed tomography of the abdomen showed a heterogeneous cystic mass containing multiple calcifications. The patient had a laparotomy at 18 days of age with excision of a well-encapsulated 6 x 5 cm retroperitoneal mass, containing many organs. Anatomicopathologic examination showed a relatively well-differentiated FIF attached to an amniotic sac by a rudimentary umbilical cord. Encephalon, coroidal plexus, vertebral bodies, rudimentary limbs, thyroid gland and teeth were identified. The postoperative period was uneventful.

Single-center experience of fetus in fetu: A case series

“…Some authors claim a male predominance [8] of FIF, while others claim an equal distribution [9], whereas our cases were exclusively female. Perhaps this phenomenon of solely female patients could be a coincidence or partially explained by observations that teratomas arise more often from the ovaries, hence it would be logical for FIF to be more prevalent in females [9]. The timing of diagnosis is most commonly reported during the first 18 months of life [10].…”