Liver metastasis from hepatoid adenocarcinoma of the sigmoid colon: A case report.

BACKGROUND: Liver metastasis from hepatoid adenocarcinoma of the sigmoid colon is a rare clinical case with atypical clinical symptoms, a high degree of malignancy, and a poor prognosis. CASE REPORT: A 28-year-old male presented with recurrent upper abdominal pain. Abdominal computed tomography revealed a hepatic mass. Laboratory tests showed markedly elevated alpha-fetoprotein (72,020 ng/mL) with negative hepatitis markers. Conventional ultrasound revealed multiple hepatic masses, some of which were hyperechoic. Contrast-enhanced ultrasound demonstrated a "fast-in and fast-out" enhancement pattern, supporting the impression of metastatic liver disease and prompting further investigation for an extrahepatic primary source, which was subsequently confirmed by colonoscopy, liver biopsy, and immunohistochemistry as hepatoid adenocarcinoma of the sigmoid colon with liver metastasis (stage IVA, pT4aN2bM1). The patient received systemic chemotherapy (initially FOLFIRI plus cetuximab, then bevacizumab plus mFOLFOX6 upon progression), achieving rapid alpha-fetoprotein decline and significant tumor shrinkage initially, followed by stabilisation on the second-line regimen. CONCLUSION: This case highlights the diagnostic value of contrast-enhanced ultrasound in alpha-fetoprotein-elevated hepatic lesions and the role of alpha-fetoprotein as a monitoring biomarker. Multimodal evaluation-integrating imaging, laboratory, histopathological, and immunohistochemical findings-is essential for accurate diagnosis and therapeutic guidance in this rare malignancy.