Fetus in fetu from newborn’s mediastinum: case report and a review of literature

Abstract

Fetus in fetu is a rare congenital anomaly, when the malformed monozygotic twin is found within the body of a living child or sometimes in an adult. We report a case of fetus in fetu diagnosed during the early third trimester of pregnancy, in the medial and inferior portions of anterior mediastinum of the dominant twin. The diagnosis was suspected by prenatal ultrasound and fetal magnetic resonance imaging. It was postnatally confirmed by CT and RTG, surgically removed after birth and histologically examined. Histologically we found well-developed organs and tissues derived from all germ layers. To our knowledge, we describe the fourth case of fetus in fetu located in the thorax, and the second case located in the anterior mediastinum. This case highlights the usefulness of prenatal ultrasound and MRI in the diagnosis of mediastinal masses, and the usefulness of complete histological examination for confirmation of diagnosis of fetus in fetu. We also reviewed the possible embryologic backgrounds of this congenital anomaly.

Fetus in Fetu: Case Report and Brief Review of Literature on Embryologic Origin, Clinical Presentation, Imaging and Differential Diagnosis

“…FIF presents in various age groups with a predominance in infancy and in the majority of cases it is diagnosed in patients younger than 18 months of age [ 1 , 2 ], with very few case reports in adults [ 3 ,– 5 ]. It commonly presents as an asymptomatic abdominal mass.…”

Perinatal diagnosis and management of oropharyngeal fetus in fetu: A case report

“…In fact, fetus in fetu exhibits various degrees of organogenesis. 20,21 Unusual locations of fetus in fetu have been reported in the cranium, 8,9 oropharynx, 13 thorax, 21 sacrum, 10 and genitalia. 16 Previously, fetus in fetu was distinguished from a mature teratoma by the presence of a vertebral column.…”

“…12,18 It is most commonly diagnosed after birth in children younger than 18 months of age 16,19 and is located in the retroperitoneal space in 80% of cases. 20,21 Unusual locations of fetus in fetu have been reported in the cranium, 8,9 oropharynx, 13 thorax, 21 sacrum, 10 and genitalia. 11,12,22 Cases of oropharyngeal or cervical fetus in fetu are especially rare with fewer than 10 cases reported in the literature ( Table 1) Mode of delivery for 2 cases was not specified; however, the birth was described as "uneventful."…”

Fetus in Fetu in the Scrotal Sac

“… 6 Most FIFs are located within the retroperitoneal space 25 ; additional sites include the cerebral ventricles, 26 mouth, 11 , 27 neck, 28 adrenal gland, 29 liver, 30 scrotum, 31 pelvis, 32 and mediastinum. 33 As FIF is a benign disorder and has been described at various sites ranging from the cranial cavity to the scrotal sac, FIF lacks specific symptoms. Most FIFs present as asymptomatic, slow-growing abdominal masses.…”