Twin Fetus-in-Fetu: The Story of an Encaged Twin

Abstract

Background: Fetus-in-fetu (FIF) features a monozygotic, diamniotic, parasitic twin enclosed within its host twin. Case report: An 11-month baby girl presented with an antenatal diagnosis of a retroperitoneal mass. Radiological findings suggested it to be a teratoma. The mass was excised in-toto, histological findings were consistent with fetus-in-fetu. Conclusions: FIF may not have identifiable vertebral bodies and limbs upon imaging. Organized organ systems help differentiate this from a teratoma.

Keywords:

• Fetus-in-fetu
• retroperitoneum
• teratoma
• parasitic twin

Acknowledgments

We sincerely thank Dr Rohit Kapoor (Senior Resident, Department of Pediatric Surgery, Kalawati Saran Children Hospital) and Sekar Lakshmilekiya, (Resident, Department of Pathology, Lady Hardinge Medical College) for their sincere efforts and valuable inputs.

Declaration of patient consent

The authors certify that they have obtained the appropriate consent from the patient’s parents. The parents have given his consent for the images and other clinical information to be reported in the journal. The parents understand that the name and initials will not be published.

Disclosure statement

The authors declare that there is no conflict of interest.

Funding

The author(s) reported there is no funding associated with the work featured in this article.