Case Report: Cholangioblastic Adenocarcinoma Initially Misdiagnosed as a Metastatic Yolk Sac Tumor: A Case Report

<ns5:p>AFP-producing cholangioblastic adenocarcinoma is an uncommon and aggressive malignancy that may mimic germ cell tumors in its clinical, histopathologic, and serologic presentation. There is diagnostic uncertainty in young patients due to markedly elevated alpha fetoprotein (AFP) levels and overlapping histopathologic and immunophenotypic features with yolk sac tumors. This case report describes the clinical course of a 29-year-old male with metastatic cholangioblastic adenocarcinoma who initially presented with difficulty breathing, weight loss, and persistent, refractory hypoglycemia in the setting of extensive hepatic tumor infiltration. The subsequent endocrine assessment ruled out insulin-mediated hypoglycemia and paraneoplastic IGF-2-mediated non-islet cell tumor hypoglycemia. The markedly elevated AFP levels and pathology led to a preliminary diagnosis of a pure yolk sac and subsequent treatment with BEP chemotherapy. Upon further pathologic examination, the diagnosis was amended to poorly differentiated metastatic adenocarcinoma of cholangioblastic origin. This case emphasizes the diagnostic intricacy of AFP-producing tumors and the value of a multifaceted clinical approach in atypical presentations.</ns5:p>