Intraperitoneal Fetus in Fetu: A Rare Cause of Abdominal Mass
A 16-month-old girl child presented with a periumbilical mass, confirmed by ultrasonography showing a heterogeneous intraperitoneal mass containing bone formations (Fig. 1). Computed tomodensitometry confirmed the presence of a skeleton within the mass (Fig. 2). The β human chorionic gonadotropin (βHCG) and α-fetoprotein (αFP) blood levels were normal. A complete extraction of the mass was performed (Fig. 3). Histological examination confirmed the diagnosis of fetus in fetu (FIF). FIF is a rare pediatric tumor (1/500,000 births) with <200 reported cases in the literature (1). An asymptomatic abdominal mass is the most common clinical presentation, usually discovered before 18 months of age (2) and in some cases during an antenatal ultrasonography (3,4). The presence of a vertebral axis and normal αFP and βHCG blood levels are useful to differentiate FIF from an immature teratoma with a potential risk of malignancy. The fetus is always anencephalic, but some organs can be present, such as gastrointestinal tract, vessels, or genitourinary tract. In almost all cases, there is a single parasitic fetus, but 2 to 5 fetuses have been reported (2). One case of a malignant recurrent mass after surgery was observed (2,5). A postsurgical supervision of 2 years, using tumor markers, is recommended.