Yaradith Urueña-Prado, Juan J Piña Perales, J. E. Vargas-Álvarez, Matías de la Rosa, Rigoberto Martínez-Parroquín, Eladio Fuentes-Soto
tlooto Summary
FIF is an exceptionally rare entity characterized by the presence of a "parasitic twin" whose pathophysiology and risk factors remain poorly understood, but it must be considered in the differential diagnosis of neonatal abdominal masses.
Abstract
BACKGROUND Among the various etiologies related to the presence of abdominal masses in newborns, the diagnosis of fetus in fetu (FIF), a term used to describe a congenital condition in which one fetus parasitizes the body, should be considered.
Clinical case We present the case of a male newborn who was found to have an abdominal mass during perinatal evaluation, leading to termination of pregnancy by cesarean section. After a thorough evaluation, a protocol was established that resulted in surgical intervention and the diagnosis of FIF.
CONCLUSIONS FIF is an exceptionally rare entity characterized by the presence of a "parasitic twin." Its pathophysiology and risk factors remain poorly understood, but it must be considered in the differential diagnosis of neonatal abdominal masses. Owing to its rarity, standardized follow-up protocols have not been established. Nevertheless, with current advances in pediatric surgery, the prognosis after complete excision is favorable.
Citation format
URUEÑA-PRADO, Yaradith, et al. Abdominal mass secondary to fetus-in-fetu in a neonate: Case report and literature review. Boletin Medico del Hospital Infantil de Mexico, 2026, 83 1(1): 62–67.