[A case report on metastatic pancreatic tumor from pulmonary adenocarcinoma that difficult to differentiate from primary pancreatic ductal carcinoma].

A woman was admitted to our department for lung adenocarcinoma and she was treated with left upper lobectomy. The carcinoembryonic antigen level had increased. Enhanced computed tomography showed a hypovascular tumor in the pancreatic tail and in the extension of the distal main pancreatic duct. Endoscopic ultrasonography (EUS) clearly showed a low echoic lesion, and histological examination revealed adenocarcinoma. On immunostaining, the lesion was diagnosed as metastatic adenocarcinoma of the lungs. The patient was treated with chemotherapy for lung cancer and survived for 4 years after diagnosis. Differentiating a metastatic lesion to the pancreas from pancreatic ductal adenocarcinoma is very important. Accurate diagnosis enables administration of appropriate treatment. In this case, EUS was especially useful for assessing the tumor in the pancreas. When patients with a history of extra-pancreatic cancer present with a pancreatic lesion, pancreatic metastases should be considered, regardless of the time elapsed since occurrence of the primary cancer. EUS-fine needle aspiration (FNA) with histological examination is the best method for definitive diagnosis of pancreatic disease in this group of patients. This approach has very high sensitivity and accuracy for the diagnosis of pancreatic metastases.