WOFAPS 2025 8th World Congress of Pediatric Surgery

Nabila Talat, Usama Aziz, Sundas Zahra, Sajid Nayyar, Jamaal Butt

University of child health sciences, The Childrens Hospital, Lahore

Introduction:

Fetus-in-fetu (FIF) is a rare congenital anomaly with an incidence of 1 in 500,000 births, characterized by a malformed parasitic twin enclosed within its host, most commonly presenting as an abdominal mass in infancy.

Case Presentation:

We report a case of a 6-month-old male infant with progressive abdominal distension and melena. Imaging revealed a well-encapsulated retroperitoneal mass containing cystic and solid components, including rudimentary long bones and a vertebral axis, closely abutting major vessels such as the abdominal aorta, inferior vena cava, branches of the celiac axis, and superior mesenteric artery, as well as the hepatobiliary structures. The patient underwent laparotomy with meticulous dissection to preserve these vital vessels and biliary channels, resulting in complete excision of the mass. Histopathological examination confirmed mature tissues from all three germ layers, consistent with FIF. The postoperative course was uneventful, and the patient remains well on follow-up.

Conclusion:

Complete surgical excision of fetus-in-fetu involving major vascular structures and the hepatobiliary tree demands meticulous preoperative planning and careful intraoperative dissection to preserve vital anatomy and prevent complications. Close proximity or involvement of these critical structures necessitates the use of advanced imaging modalities and intraoperative tools such as Doppler ultrasound and cholangiography to ensure safe and effective removal. Although prognosis following complete excision is excellent, vigilant postoperative surveillance remains essential due to the rare potential for recurrence or malignant transformation.