Fetus-in-fetu in an adult patient. Report of an exceptional case and review of the literature

The name fetus-in-fetu designates the presence of a tumoral mass containing a homunculus. Fewer than 70 cases have been reported in the literature since its first description about 1800. This entity usually presents in childhood and it is exceptional in adult life. Ther is an interesting debate regarding its origin and mainly its relationship with teratomas and the normal process of twin formation. We report here a case seen and treated at our institution with a review of the literature and some hipothesis on its development.