yemenjmedYemen Journal of MedicinecoVolume 4 Issue 2MultidisciplinaryEnglishMay-August 2025NNY20250922ArticleFetus-in-Fetu Presenting as a Symptomatic Mass in an Infant: A Case ReportEnglishY468470Sandip KumarRahul1EnglishNRupeshKeshri1EnglishYDigamberChaubey2EnglishYMd Asjad KarimBakhteyar3EnglishY10.63475/yjm.v4i2.0188Fetus-in-fetu represents an extremely unusual condition where a malformed parasitized twin with an organized vertebral column is present within the body of its host, leading to a variety of symptoms due to its mass effect. Its pathogenesis and features differ from both teratoma and fetiform teratoma. Detailed radiological evaluation helps in the assessment of the local anatomy and in planning the surgical procedure. The clinical features of a 9-month-old female with progressive abdominal distension and feeding difficulties are described. A firm, non-tender leftsided abdominal mass on palpation was found to be a well-defined encapsulated retroperitoneal lesion with bony structures resembling a vertebral axis on abdominal sonography and computed tomography. Surgical excision revealed an encapsulated mass containing rudimentary limb buds, hair, and partially developed vertebral elements. Histopathology confirmed the diagnosis of fetus in fetu. The postoperative course was uneventful, and the patient remained asymptomatic on follow-up.EnglishFetus-in-fetu, vertebral column, teratoma, fetiform teratomahttps://www.yemenjmed.com/admin/abstract?id=239References1619