First Case Report of Adnexal Fetus in Fetu

Abstract Teratomas are common neoplasms in the female adnexa. Rarely, the mass may be highly organized and resemble a fetus. There is an ambiguous and controversial line between fetiform teratoma and fetus in fetu (FIF) as differential diagnoses of a fetiform mass and there is still debate about considering FIF and fetiform teratoma as one entity or two. Classically, the presence of vertebral column often with a relatively proper arrangement of other organs around the central axis favor the diagnosis of FIF over teratoma. However, clinical discrimination for the choice of treatment seems to be unnecessary and the patient should be clinically followed to exclude the probable malignant potential. Based on previously proposed criteria and the presence of the vertebral organization in the radiological and histopathological assessment of the fetiform mass, we present an extremely rare case of adnexal FIF in a 10-year-old girl presented with acute abdominal pain.