Fetus in fetu is an very rare condition in which a vertebrate fetus is incorporated within its twin. Although a number of cases were reported at 3rd trimester of gestation or postnatally, the authors present a retroperitoneal fetus in fetu with 9 x 7 x 6 cm sized cystic mass that was diagnosed at 2nd trimester using ultrasonography and confirmed on a computed tomography scan after birth. The mass was successfully excised postnatally and consistent with a fetus in fetu by pathological confirmation. Solid mass was surrounded by a fluid-containing sac and showed highly ordered organogenesis around an axial vertebral column.
Diagnosis* ; Fetus* ; Humans ; Organogenesis ; Parturition ; Pregnancy ; Spine ; Ultrasonography ; Vertebrates