Pelizzari Mario,  Montalvetti Pablo

Final Pr. ID: Poster #: CR-009

Case Presentation
A 28-year-old patient, undergoing her second pregnancy, with no pathological or toxic clinical history, presented with an intra-abdominal fetal mass identified during 34-week gestational age routine ultrasound. A Fetal Magnetic Resonance Imaging (fMRI) was performed, revealing findings compatible with Fetus in Fetu (FiF).

Findings
The ultrasound examination revealed an intraperitoneal mass in the middle of the fetal abdomen, solid, heterogeneous, with fatty areas and calcified structures resembling long bones. Vascularized by the superior mesenteric artery and displaced abdominal organs without invading them. These findings were confirmed later with fMRI.
Birth was delivered via cesarean section at 38 weeks. Due to suspicion of FiF vs. Teratoma (Tt), tumor markers were tested with negative results. During follow-up, FiF growing was observed, leading to the decision to surgically remove the tumor at two months of age. Anatomopathologic examination confirmed the diagnosis of FiF. A computed tomography of the surgical specimen revealed characteristic FiF signs.

Discussion
With an estimated incidence of 1 in 500,000 births, FiF is a condition in which, due to abnormal embryogenesis in a monochorionic diamniotic pregnancy, one fetus grows abnormally within the body of the other. The diagnosis is based on imaging findings and is characterized by the presence of a separate vertebral column and the development of organs around this axis, indicating an early stage of fetal development. These features distinguish it from a highly differentiated Teratoma.
Although it is a benign condition, the mass can affect surrounding structures. Prenatal diagnosis is more feasible nowadays, and suspicion should arise when an encapsulated cystic mass with calcified components is identified.

Conclusion
Imaging plays a crucial role in the diagnosis due to its similarity to a teratoma, which could have malignant potential. Surgical treatment is required, and early detection allows for a favorable prognosis. Read More

Authors:  Pelizzari Mario , Montalvetti Pablo

Keywords:  Fetal MRI, Fetus in fetu

Singer Julia,  Bodea Jessica,  Gerard Perry,  Sandoval Claudio

Final Pr. ID: Poster #: CR-061

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. Read More

Authors:  Singer Julia , Bodea Jessica , Gerard Perry , Sandoval Claudio

Keywords:  Germ Cell Tumors, Fetus in Fetu, Maternal-Fetal Choriocarcinoma