Fetus in fetu: two case reports and review of literature

Fetus in fetu is a rare disorder. Its embryopathogensis and differentiation from teratoma has not been well established. It is a parasitic twin of a diamniotic monozygotic twin. Here we report, two cases of fetus in fetu with review of literature. In case report 1, a 2-year-old boy was referred for asymptomatic lump in abdomen since birth. X-ray showed the mass in the abdomen with some calcification and fluid inside. CT scan reported a heterogenous mass in the retroperitoneum with bony malformation. CT showed presence of three vertebrae in it. After surgically excising the mass and opening the sac it showed presence of trunk and two limbs with one of the limbs having a nail. Histopathology showed presence of GI tract. In case report 2, 4 month female was found to have lump in the abdomen by housemaid while bathing. X-ray showed a soft tissue shadow while ultrasonography revealed cystic mass arising from right kidney. CT suggested cystic mass with calcification not arising from kidney. During exploration whole mass was excised and there was frank fetus inside it. Histopathology confirmed presence of four vertebral bodies with germ layers. Although fetus in fetu is rare condition, correct diagnosis using imaging can be made before surgery. Complete excision is curative.