Purpose or Case Report: Germ cell tumors (GCT) comprise benign and malignant neoplasms arising from variation of normal differentiation of totipotent primordial germ cells. Pediatric GCT are rare, representing 3% of all malignant pediatric tumors with an estimated incidence of 0.9/100.000 children up to 15 years of age. Germ cell tumors are located in the gonads, sacrococcygeal region, retroperitoneum, anterior mediastinum and pineal gland. Herein we describe a case of fetus in fetu and maternal-fetal choriocarcinoma.
Methods & Materials: A clinical and radiographic review of 2 unusual pediatric GCT cases.
Results: Case 1 – Fetus in fetu – 7-month-old boy presented with non-bilious emesis and abdominal mass. Abdominal computed tomography showed a mass with cystic and solid components and bone. Laparotomy revealed a mass containing ribs and skull, and because of a shared blood supply was deemed unresectable. Post-operative serial computed tomographic evaluations showed dental eruptions (Figure 1). The mass was never resected and he remains alive and well 9 years post-biopsy.

Case 2 – Maternal-fetal choriocarcinoma – 32-year-old women presented with left shoulder pain and difficulty breathing during the 9^th month of gestation. After delivery of a healthy appearing boy, she was diagnosed with stage 4 choriocarcinoma. Computed tomography of the chest revealed multiple lung nodules (Figure 2A). Concurrently, her 1-month-old baby boy was diagnosed with gestational choriocarcinoma. Computed tomography of the liver demonstrated a large heterogeneous hypervascular mass within the left hepatic lobe, situated between the middle and left hepatic veins (Figure 2B). Computerized tomography of the chest revealed peripheral nodular opacities in both lungs, and of the brain and orbits showed hemorrhage in the choroid of the right globe posteriorly and medially. Mother and infant were treated with cisplatin, etoposide and bleomycin and had normalization of serum βHCG. Figure 3A and 3B reveal interval tumor responses. The mother and boy remain alive without any evidence of disease on physical examination and serum tumor marker, and the boy has no vision in the right eye and wears hearing aids.
Conclusions: Despite the unusual rarity of our cases they provide us with an opportunity to educate and fascinate our colleagues.