Anaplastic carcinoma of the pancreas derived from an intraductal papillary mucinous neoplasm: a case report.

We report the case of a patient with anaplastic carcinoma of the pancreas derived from an intraductal papillary mucinous neoplasm. A 51-year-old man was reported to have an enlarged cystic lesion in the pancreatic head. Contrast-enhanced computed tomography revealed a multifocal cystic lesion with an internal contrasted nodule. The patient was diagnosed with IPMN with high-risk stigmata and underwent pylorus-preserving pancreaticoduodenectomy. The pathological diagnosis was anaplastic carcinoma of the pancreas, classified as pleomorphic type, derived from intraductal papillary mucinous neoplasm. Based on the morphological features and immunohistochemical reactivity for MUC1, MUC2, MUC5AC, and MUC6, the intraductal papillary mucinous carcinoma was classified as pancreatobiliary type. Immunostaining for tumor-suppressor genes CDKN2A(p16), TP53, SMAD4, and STK11 was performed; aberrant expression of p53, Smad4, and STK11 was observed in intraductal papillary mucinous carcinoma and anaplastic carcinoma. The patient's postoperative course was uneventful; however, para-aortic lymph node metastasis was observed 10 months postoperatively. Immunohistochemical analysis of intraductal papillary mucinous neoplasm subtypes and tumor-suppressor genes may contribute to predicting prognoses in such cases.