Fetus in fetu: Review of the literature over the past 15 years

Fetus in Fetu (FIF) is a rare congenital anomaly in which a malformed parasitic twin is found within the body of a living child or adult. In this case report, an 18 month-old male child presented with a large abdominal mass and failure to thrive. Imaging studies confirmed the presence of a large retroperitoneal fetus in fetu with significant mass effect of the adjacent structures. A surgical resection was performed and pathology confirmed the diagnosis. These rare cases have become more frequently reported and a review of the literature for the past 15 years will describe the demographics, updated genetic findings, pathology and outcomes of this unusual tumor. Recent findings will also discuss an infrequent association with teratomas that may warrant a longer follow-up for surveillance of malignancy.