An 83-year-old woman with left lower abdominal pain was referred to our hospital. Ultrasonographic examination showed a cystic lesion in the pancreatic body. Magnetic resonance cholangiopancreatography and computed tomography revealed dilatation of the main pancreatic duct in the pancreatic body and tail. However, there was no evidence of distinct tumorous lesions. Endoscopic ultrasonography of the pancreatic duct revealed a hypoechoic mass (major axis, 5 mm). Pancreatic cancer was suspected. Endoscopic retrograde cholangiopancreatography was performed, and an endoscopic nasopancreatic drain was placed. Cytologic examinations of pancreatic juice showed atypical cells. The possibility of pancreatic cancer could not be ruled out, and distal pancreatectomy, splenectomy, and D2 lymph-node dissection were performed. Postoperative pathological examination showed low-grade pancreatic intraepithelial neoplasia in the main pancreatic duct and high-grade pancreatic intraepithelial neoplasia in the lesion. Pancreatic intraepithelial cancer (carcinoma in situ) was diagnosed.
