Ilyas Bader, Nadeem Akhter, Madiha Sajjad, Ahmareen Khalid, Naeem Uz Zafar Khan, Anwar ul Haq, Naeem uz Zafar Khan.
Twin fetus in fetu - a very rare entity: A case report with review of literature.
Pak J Med Sci Jan ;19(4):306-9.

Objective: 1) To report a very rare condition of conjoined twining in fetus in fetu in an infant. From literature it appears to be the 4th case being reported. 2) To emphasize the importance of proper examination of the fetus in fetu grossly by doing extensive dissection, radiologically and detailed histological tissue examination from several sites. Design: Detailed report of an unusual intra-abdominal mass in an infant. Setting: Department of Pediatric Surgery, Children Hospital, PIMS, Islamabad. Results: Successfully treated with surgical removal and interesting diagnosis emerged. Conclusion: Twin fetus in fetu (FIF) is a very rare anomaly due to an abnormal embryogenesis of fetus during pregnancy. Malformed fetus grows in the body of co-twin and it is frequently detected as an abdominal mass. There is no clear distinction between the term of FIF and fetiform teratoma (FT). We are reporting a case in which a girl was referred as a case of nephroblastoma but at operation and on detailed examination of the specimen it turned out to be a case of twin fetus in fetu.

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