Fetus in Fetu in the Scrotal Sac

Abstract

Fetus in fetu (FIF) is a rare congenital anomaly. The most common site at which FIF occurs is the retroperitoneum. The mechanisms underlying the development of FIF have not been fully elucidated. The monozygotic twin theory postulates that FIF results from the unequal division of the totipotent cells of the blastocyst. However, the monozygotic twin theory does not explain all cases of FIF.Herein, we describe the clinical characteristics of a 20-day-old infant with scrotal sac swelling. Ultrasonography and computed tomography revealed the presence of a mass consistent with a FIF rather than a teratoma. Surgical removal and a subsequent pathological evaluation demonstrated that the anencephalic fetus exhibited limb buds adjacent to a palpable vertebral column, supporting the diagnosis of FIF. The infant had an uneventful recovery and was discharged on the fifth postoperative day. In the present report, the pathogenesis, presentation, diagnosis, and management of FIF, as well as new concepts emerging in this area of research, are discussed.Although the majority of cases of FIF may be diagnosed preoperatively, FIF should be distinguished from teratoma because the latter has substantial malignant potential. The recommended treatment for FIF is complete resection. To confirm the diagnosis of FIF, pathological examination, karyotyping, serologic marker assessment, and DNA restriction site mapping should be performed after removing the mass. Although FIF is thought to be a benign disorder, follow-up is necessary as a precaution against malignant recurrence, which has been described once.

A case report of fetus in fetu with an aorta-like structure visualized by contrast-enhanced CT

“…FIF is a cystic mass containing fetus-like structures found mainly in the retroperitoneum of infants. It is a rare condition with less than 200 cases reported worldwide [4] .…”

“…The most common site of FIF is the retroperitoneum (72%-80%), and less frequent sites include intracranial sites, oral cavity, neck, mediastinum, thorax, liver, adrenal gland, spleen, sacrococcygeal regions, and scrotum [2] , [3] , [4] . FIF typically presents during infancy and early childhood; however, there are several case reports in which FIF was found during adulthood [3] .…”

“…Multiple theories have been proposed with regard to the etiology of FIF. The most common theory is abnormal embyogenesis in diamniotic monochorionic twins, in which a parasitic fetus is incorporated into the body of its twin partner and grows inside of it [1] , [2] , [3] , [4] . Another theory is that FIF is a highly differentiated form of teratoma [1] , [2] , [3] , [4] .…”

Case report: rare congenital anomaly diagnosed by ultrasonography

“…The most common localization of FIF is in the retroperitoneal space, but has already been reported in the abdomen, scrotum, kidneys, adrenal, mediastinum, thorax, skull and lymph. 10,11 It is usually not a malignant condition, but it can cause abdominal distension, problems during feeding, vomiting, jaundice, renal and respiratory disorders. 12 In this case, the patient presented a stable clinical picture, without physical alterations, absence of jaundice and satisfactory suction.…”

The entrapped twin: a case of fetus-in-fetu

“… 4 Surgical excision also allows for relieve of obstruction and prevention from further compression. 9 …”