[Fetus in fetu: report of 2 cases and analysis of the literature].

Foetus in foetu is a very unusual cause of abdominal mass in the infancy. Twenty cases only have been quoted in the literature. Two others cases are added, concerning two girls: a three months infant, second born from a genuine twin pregnancy, and a four weeks newborn whose the mass was discovered before the birth, on routine ultrasonography. In together, the diagnosis was made in operating room, then confirmed by pathologic studies. Literature data are recorded, and the difference between teratomas and foetus in foetu is point. The pathogeny remains obscure. It could result from the inclusion of a parasite twin in his bearer, become during embryologic stage of the delimitation.