A Diagnostically Challenging Case of Autoimmune Pancreatitis Due to Contamination of the Pathological Specimen with Early Gastric Cancer.

A 73-year-old man with worsened diabetes underwent abdominal computed tomography and was diagnosed with localized enlargement of the pancreatic tail. Based on the suspicion of autoimmune pancreatitis, endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) was performed. A cytologic examination showed findings suggestive of adenocarcinoma. Due to discrepancies between the imaging and pathological findings, esophago-gastro-duodenoscopy was performed. An extensive early gastric cancer lesion was detected in the posterior wall of the gastric corpus. It was therefore likely that puncturing through the tumor resulted in the contamination with cancer tissue. The possibility of a concomitant malignancy should be considered in EUS-FNA, and thorough examinations should be conducted.