Using Next-generation Sequencing as Auxiliary Tool to gastric cancer with multiple intrahepatic neoplasms Diagnosis:primary cholangiocarcinomas or liver metastasis

Since the pathogenesis of gastric cancer (GC) is generally disguised, with no unique clinical symptoms and manifestations, most patients have evolved to the advanced stage at the time of diagnosis when liver metastases are more likely to develop. Clinical diagnosis of liver metastasis in GC mainly depends on physical imaging methods, such as B-scan ultrasonography, computed tomography (CT), magnetic resonance imaging (MRI), etc. Histopathologic diagnosis is the gold standard for differentiating both primary cancer and metastasis. Next-Generation Sequencing (NGS), a relatively new technique, is increasingly being employed in clinical settings to guide diagnosis and treatment. Here, we report a patient with gastric cardiac adenocarcinoma who developed multiple intrahepatic neoplasms more than one year after total gastrectomy. Enhanced chest CT showed there may be metastatic lesions, but primary liver carcinomas should be excluded, while percutaneous core needle biopsy of the liver suggested that it was invasive or metastatic carcinoma and immunohistochemistry (IHC) was recommended for further diagnosis. Then further IHC examination suggested that it was consistent with cholangiocarcinoma. We treated the patient as having double primary carcinoma of GC and cholangiocarcinoma. However, based on the consistency of genetic testing in gastric and liver tissues for somatic mutations and certain copy number variants (CNVs), as well as the imaging examination, with the assistance of multidisciplinary team (MDT), finally we concluded that the patient should be diagnosed with a GC with liver metastasis, which suggested that NGS, a promising and auxiliary diagnostic tool, can be beneficial when the histopathology is ambiguous.