Postnatal growth of fetus-in-fetu.

A 6-month-old-boy who presented with an abdominal mass disclosed a well-formed fetus in the retroperitoneum. This mass was retrospectively noted at the age of 1 month. Comparison of two radiographic examinations done 5 month apart clearly demonstrated the enlargement of an included fetus in the bearer's abdomen. Our report of this rare condition focuses on the growth of the fetus-in-fetu detected by roentgenograms.