title: Pancreatic ductal adenocarcinomas with multiple large cystic structures: a clinicopathologic and immunohistochemical study of seven cases.
abstract: OBJECTIVE
  Pancreatic ductal adenocarcinoma (PDA) with cystic change is classified into several types according to the features of the cysts; however, those tumors do not constitute a uniform group, and the classification is controversial. In this study, we have described a series of cystic PDAs that show distinctive and previously unreported morphologic and immunohistochemical features.
  
  
  METHODS
  We analyzed 200 cases of PDA treated surgically at a single institution, and extracted the clinical and histopathological features of 7 tumors showing multiple large cystic (MLC) structure.
  
  
  RESULTS
  Preoperative radiographic images revealed a multilocular mass in the pancreas which was similar to intraductal papillary mucinous neoplasm or mucinous cystic neoplasm. These tumors were associated with more than 5 large cystic structures and numerous intratumoral microcysts lined by epithelial cells with various degrees of atypia. The average maximal diameter of the cysts (3.7 cm) was much larger than that of previously reported. Immunohistochemically, the cyst-lining epithelia were almost negative for mucin core protein (MUC) 1, MUC2, and MUC6, and showed only focal staining for MUC5AC. Maspin, CEA, and p53 were strongly positive, and the Ki-67 labeling index was high in both cells in solid areas and cyst-lining epithelia.
  
  
  CONCLUSIONS
  We considered the MLC structures in PDA to be a mixture of ectatic neoplastic glands and retention cysts with ductal cancerization or pancreatic intraepithelial neoplasia (PanIN); however, they might represent a new entity of cystic PDA because of the unusually large size of the dilated cysts.
authors.affiliation: Department of Surgical Pathology, Hokkaido University Hospital, Sapporo, Hokkaido, Japan.
authors.forename: Takeo
authors.initials: T
authors.lastname: Nitta
authors.forename: Tomoko
authors.initials: T
authors.lastname: Mitsuhashi
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Hatanaka
authors.forename: Satoshi
authors.initials: S
authors.lastname: Hirano
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Matsuno
mesh_terms: D000368:Aged; D002272:Carcinoembryonic Antigen / Q000378:metabolism; D021441:Carcinoma, Pancreatic Ductal / Q000401:mortality / Q000473:pathology*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D019394:Ki-67 Antigen / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D009077:Mucins / Q000378:metabolism*; D010179:Pancreas / Q000378:metabolism; D010190:Pancreatic Neoplasms / Q000401:mortality / Q000473:pathology*; D011518:Proto-Oncogene Proteins / Q000235:genetics; D016283:Proto-Oncogene Proteins p21(ras); D015843:Serpins / Q000378:metabolism; D016019:Survival Analysis; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D018631:ras Proteins / Q000235:genetics
chemical_list: D002272:Carcinoembryonic Antigen; C117307:KRAS protein, human; D019394:Ki-67 Antigen; D009077:Mucins; D011518:Proto-Oncogene Proteins; C085344:SERPIN-B5; D015843:Serpins; D016159:Tumor Suppressor Protein p53; D016283:Proto-Oncogene Proteins p21(ras); D018631:ras Proteins
keywords: Cyst; Ductal adenocarcinoma; Multiple large cysts; PanIN; Pancreas