Imaging findings in Fetus-in-fetu-misdiagnosed commonly as teratoma

Abstract

Fetus in fetu is a rare condition associated with abnormal embryogenesis in a diamniotic, monochorionic pregnancy, wherein one of the fetus is enclosed within the body of another normally developing fetus. It should be differentiated from a teratoma because of the later’s malignant potential. Here we report a case of 2 months old girl child who presented with complaints of abdominal distension. USG showed a solid cystic retroperitoneal mass resembling an anencephalic fetus. Contrast enhanced Computed tomography (CT) showed similar findings with visualization of bones resembling femur, sacrum and vertebrae. Findings were correlated with MRI and post-op pathology. The preoperative diagnosis of FIF is based on the observation of vertebral column or limbs in a mass on imaging modalities and our case meets the required criteria.