Abstract
An 80-year-old man came to our hospital for investigation of hyperamylasemia and plain chest X-ray abnormality. Computed tomography revealed a 17-mm tumor with pleural indentation in the left upper pulmonary lobe. FDG-PET showed high FDG accumulation in the left lung tumor, left hilar lymph nodes, and gastric body. CT-guided needle biopsy of the left lung tumor showed adenocarcinoma, while gastroscopy revealed an irregular ulcerated tumor. We diagnosed this case as gastric cancer with either pulmonary metastasis or primary lung cancer, and a staged operation comprising left upper lobectomy and distal gastrectomy was performed. Histopathological examination of the resected stomach showed poorly differentiated adenocarcinoma. Because histopathological findings for the lung adenocarcinoma resembled those of the gastric cancer, the lung tumor was diagnosed as metastasis of gastric carcinoma. In addition, anti-salivary-type amylase staining revealed positive results for the gastric tumor. Serum amylase level was 425 U/L preoperatively, decreasing to 65 U/L and 40 U/L after the left upper lobectomy and distal gastrectomy, respectively. Based on the hyperamylasemia and positive anti-salivary-type amylase staining, the gastric cancer was determined to be an amylase-producing tumor.
