Fetus in fetu.
Fetus in fetu occurs due to aberration of monozygotic twinning. A 16-year-old boy presented with abdominal pain and mass. Laparotomy revealed an anencephalic fetus within an encapsulated retroperitoneal mass. Pathologic examination confirmed rib formation with a primitive vertebral column with bone marrow. There was no other organogenesis.
Adolescent↗