S2403 Yolk's on You: Two Cases of Yolk Sac Tumor of the Liver Masquerading as Hepatocellular Carcinoma

Abstract

INTRODUCTION: Yolk sac tumors (YST) are malignant germ cell tumors commonly arising from the testes or ovaries. Due to their rarity, they are not considered in the differential for hepatic tumors. Diagnosis relies on histology. We report 2 interesting cases of primary hepatic YST. CASE DESCRIPTION/METHODS: Case 1: A 60-year-old African American male presented with right upper quadrant pain for 4 weeks. Evaluation was significant for elevated ALP, AST, and ALT. Acute viral hepatitis panel was negative. CT was significant for multiple infiltrative masses in a non-cirrhotic liver with the largest being 27 cm. AFP was noted to be >13,500 ng/mL. A biopsy revealed primary YST of the liver. He received 4 cycles of VIP with noted improvement in LFTs. Case 2: A 77-year-old female presented with right upper quadrant pain and a 10 lb weight loss over several weeks. Evaluation demonstrated elevated ALP. AFP was noted to be 1.1 million ng/mL. A CT demonstrated multi focal ill-defined hypodense solid hepatic masses, the largest measuring 12.9 cm. A biopsy was consistent with YST. She was started on carboplatin and etoposide, however she rapidly declined after the first cycle of chemotherapy. DISCUSSION: YST is a non-seminomatous germ cell tumor composed of primitive germ cells predominantly arising from the testes or ovaries. However, there have been reports of extragonadal sites such as mediastinum, bladder, and pineal gland. First reported in 1975, YST are more common in young females, Asian ethnicity, and respond well to chemotherapy. In contrast, hepatocellular carcinoma (HCC) occur more commonly in males, >50 years old, and respond poorly to systemic chemotherapy. Both HCC and YST can present in non-cirrhotic livers and with elevated AFP. A biopsy of the liver mass is necessary in non-cirrhotic livers and in those cases in which radiographic features characteristic of HCC are not apparent. On imaging, YSTs will appear as cystic lesions with central necrosis or calcification if associated with teratoma. On histology, YSTs have a characteristic Shiller-Duval body and stain negative for HepPar-1 and Arginase -1 which are positive in HCC. The treatment for YSTs usually involves resection, adjuvant chemotherapy or chemotherapy alone. An ovarian or testicular ultrasound is not necessary prior to initiating treatment. Although rare, primary yolk sac tumor of the liver should be considered as a differential diagnosis in young non-cirrhotic patients with large cystic tumors with necrosis and significantly elevated AFP.Figure 1.: Case 1, Figure 1: Abdominal computed tomography with contrast showing multiple infiltrative liver masses.Figure 2.: Case 2, Figure 2: Axial abdominal computed tomography (CT) showing 6.8 2.9 cm liver mass.Table 1.: Comparison of HCC and YST.