Fetus-in-fetu: A case report with molecular analysis

This is the report of a case of fetus-in-fetu diagnosed in a 3-month-old bo y and found to be located in the upper retroperitoneum. The entity was dist inguished from teratoma by the presence of vertebral axis with limb buds. I t corresponded to a diamniotic, monochorionic, monozygotic twin, Complete e xcision of the mass was performed. Radiological, histopathologic, and DNA f ingerprinting studies performed on fetus-in-fetu specimen showed that the f etus was a monozygotic twin. Copyright (C) 1999 by W.B. Saunders Company.