Abstract: BACKGROUND: Fetus in fetu (FIF) is an exceptionally rare and intriguing congenital anomaly characterized by the presence of a malformed, parasitic twin within the body of a host twin. This condition poses unique diagnostic and therapeutic challenges, particularly in the realm of radiology. This condition is usually confused with teratoma and cystic meconium peritonitis. This study analyses and documents the various presentations and imaging features across different modalities in a series of cases presented at our institution. OBJECTIVE: To review and summarize the imaging findings of FIF cases, highlighting the diagnostic features and differential diagnosis. METHODS: We conducted an analysis of different radiological studies from a series of patients diagnosed with FIF at our institution. Cases were selected based on imaging findings consistent with the condition. Data including X-ray, ultrasound, computed tomography (CT), and magnetic resonance imaging (MRI) were analyzed to elucidate characteristic features and variations. RESULTS: The case series includes four patients diagnosed with FIF, ranging from the antenatal period till adulthood. Imaging provided detailed anatomical localization and differentiation from other abdominal masses, such as teratomas. Key findings in the radiological imaging modalities included the presence of well-defined, encapsulated masses with varying degrees of organ differentiation and ossification. CONCLUSION: Radiological imaging plays a crucial role in the diagnosis and management of FIF. X-ray, ultrasound, CT, and MRI each contribute unique insights into the condition’s presentation and assist in differentiating it from other abdominal anomalies. Early and accurate imaging diagnosis is essential for effective surgical intervention and optimal patient outcomes. Continued research and case documentation will enhance our understanding and improve management strategies for this rare anomaly.
Jegannivas et al. (Wed,) studied this question.