Hepatoid Adenocarcinoma of the Stomach with Liver Metastasis Misdiagnosed as Hepatocellular Carcinoma: A Case Report and Literature Review.

Hepatoid adenocarcinoma of the stomach (HAS) is a rare, highly aggressive gastric cancer subtype with a poor prognosis. Herein, we report a 61-year-old male initially misdiagnosed with multifocal hepatocellular carcinoma (HCC) at another hospital in December 2025, based on multiple hepatic nodules on MRI and elevated serum AFP. Admitted to our hospital in January 2026 for worsening fatigue and anorexia, he had severe anemia, a family history of gastric cancer and progressively rising AFP. Gastroscopy and histopathology confirmed HAS with multiple liver and lymph node metastases. After one cycle of XE-LOX plus cadonilimab palliative chemotherapy, the disease progressed rapidly with sharply elevated AFP and new metastases, and the patient refused further treatment. This case shows HAS is easily misdiagnosed as HCC, especially with occult gastric lesions and liver metastasis. Imaging and tumor markers have limited diagnostic value, while gastroscopy and histopathology are the gold standard. Comprehensive clinical evaluation is essential to reduce misdiagnosis. HAS is characterized by rapid disease progression and poor therapeutic response. Nevertheless, as a novel biomarker, the diagnostic and therapeutic value of CLDN18.2 in this disease remains to be further validated by large scale clinical data.