A 69-year-old woman was referred to our hospital after incidental identification of a pancreatic mass during follow-up for diabetes mellitus. Various imaging examinations showed a tumor in the main pancreatic duct, without apparent hypersecretion of mucin. Brush cytologic examination revealed class V disease (adenocarcinoma). Because preoperative examination suggested an intraductal neoplasm with associated invasive cancer, total pancreatectomy was performed. Histological examination, based on current World Health Organization classifications, suggested a diagnosis of intraductal tubulopapillary neoplasm. A small cystic lesion adjacent to the intraductal tubulopapillary neoplasm was incidentally diagnosed as serous cystadenoma. The patient has remained well without recurrence as of 24 months postoperatively. Computed tomography and magnetic resonance imaging of the intraductal tubulopapillary neoplasm suggested ductal cell carcinoma of the pancreas rather than intraductal papillary mucinous neoplasm. Distinguishing intraductal tubulopapillary neoplasm from ductal cell carcinoma is clinically important, as intraductal tubulopapillary neoplasm has a favorable prognosis after curative resection.