Abstract

e16371 Background: Yolk Sac Tumor of the Liver (YSTL) is an extremely rare extragonadal germ cell tumor with gonadal origin and histology which presents in the liver. While uncommon, this tumor is often misdiagnosed due to the similarities between YSTL, HCC, and Hepatoblastoma (HB). As this cancer can present with serious mortality, our review aimed to evaluate clinical findings, diagnostic workup, and treatments in patients with YSTL. Methods: We performed a literature search in PubMed from 1950 to October 2023 using filters English language and full text with keywords “Yolk sac tumor of the liver”, “Endodermal Sinus tumor of liver”, “Hepatic Yolk sac tumor”, and “Hepatic Endodermal sinus tumor”. We also conducted a combined search query with all these search terms and “primary”. Patients were included in the study if they had primary YSTL and no other malignancy. Results: Our results looked at 19 patients ranging from 15 months to 64 years with median age being 27 years, including 13 female (68%) and 6 male (32%) patients, percentages reflect the total number of patients. The key presenting symptom in adults was abdominal pain (55%), while the key presenting symptom in children was abdominal distention (63%). All patients in the study had a diagnostic workup that included imaging and pathology. Imaging included CT Abdomen (68%) and MRI (37%), in 58% of patients a solitary mass was seen on imaging, while in 42% of patients multiple hepatic masses were seen. Histology workup mainly noted Shiller Duval Bodies(SDBs)(76%). Molecular Markers included AFP(42%), Alpha-1 anti-trypsin(A1AT)(26%), SALL4(21%), Pancytokeratin(PK)(11%), and Placental-like alkaline phosphatase(PALP)(11%). Treatment included chemotherapy(58%), surgery(47%), transplant(11%), and trans-arterial chemoembolization(5%). Out of the 11 patients who were treated with chemotherapy, 91% received the bleomycin, etoposide, and cisplatin (BEP) regimen. The remaining 9 % of patients received a regimen of cisplatin, adriamycin, and pepleomycin. Conclusions: YSTL is a unique tumor presenting in patients of all ages, tending to present vaguely often with abdominal pain or distension. Diagnostic workup often includes abdominal imaging (MRI and CT Abdomen) and pathology with a focus on SDBs on histologic examination and stains like AFP, A1AT, SALL4, etc. Treatment often focuses on surgery and chemotherapy, notably BEP. Though both HCC and HB traditionally present as a multifocal liver mass on imaging along with positive staining for AFP and PK, our study helps differentiate this tumor from others by emphasizing the importance of SDBs in diagnosis and highlighting new molecular markers to help make the diagnosis easier.