Foetus in Fetu: The Hidden Twin Within

Foetus in fetu (FIF) is an exceptionally rare congenital anomaly in which a malformed monozygotic twin develops within its host, often presenting as an intra-abdominal mass. Diagnosis is primarily radiological, based on the identification of organised foetal skeletal structures. Fewer than 200 cases have been reported worldwide.

We report a case of a 29-year-old gravida 2 woman whose antenatal scan revealed a complex cystic lesion in the foetal abdomen. Postnatal imaging confirmed well-formed foetal parts consistent with FIF. Laparoscopy was initially performed to assess anatomy, delineate vascular supply, and plan surgery, followed by successful laparotomy and complete excision of the mass. The postoperative course was uneventful, and the patient recovered fully.

Although extremely uncommon, early recognition through imaging and laparoscopic evaluation allows precise surgical planning. Complete excision is curative and ensures excellent outcomes.