Case Report: AFP-producing gastric hepatoid adenocarcinoma with multiple liver metastases – integrating quantitative imaging and diagnostic decision analysis

Background Hepatoid adenocarcinoma of the stomach (HAS) is a rare and aggressive gastric cancer variant with both glandular and hepatocellular differentiation. The AFP-producing subtype is strongly associated with early liver metastasis and poor prognosis, presenting significant diagnostic challenges due to its resemblance to hepatocellular carcinoma (HCC). Case summary A 68-year-old male presented with progressive dizziness and fatigue. Initial contrast-enhanced abdominal CT revealed a hypervascular gastric antral mass with quantitative enhancement values of 52 ± 3 HU (arterial), 78 ± 5 HU (portal), and 85 ± 4 HU (delayed) in the submucosal layer. Serum AFP was markedly elevated at 918.88 ng/mL. Gastroscopic biopsy confirmed AFP-producing HAS. The patient underwent Billroth II gastrectomy. Four months postoperatively, surveillance CT identified multiple new hypervascular liver metastases, prompting right hepatectomy followed by adjuvant radiochemotherapy. At three-month follow-up, the patient was asymptomatic with normalized tumor markers. Conclusion This case illustrates the utility of quantitative CT enhancement analysis for characterizing the hypervascular phenotype of AFP-producing HAS and proposes a conceptual diagnostic framework to differentiate HAS from HCC. Multidisciplinary collaboration and systematic serum AFP screening in patients with gastric lesions are essential for optimal management of this aggressive malignancy.