Foamy gland
adenocarcinoma is a variant of
pancreatic ductal carcinoma, whose precursor has not been described. We describe here the morphologic and immunohistochemical features of the pancreatic intraepithelial
neoplasia (PanIN) lesions associated with invasive foamy pancreatic
adenocarcinoma. The staining properties and morphologic and immunohistochemical features of 3 foamy PanIN lesions were compared with those of 7 pancreatic foamy gland
adenocarcinomas.
Hematoxylin and
eosin, Mayer
mucicarmine,
periodic acid-Schiff, and
Alcian blue stains were available for review in all cases. Immunohistochemical labeling for
cytokeratin (CK)7, CK20,
carcinoembryonic antigen polyclonal, MUC1, MUC2, CDX2, p53, and
cyclin D1 was performed. The PanIN-1 lesions were found in the nonneoplastic pancreas and were similar to the PanIN-1 lesions of ordinary
pancreatic ductal carcinoma. The PanIN-2 and -3 lesions were recognized immediately adjacent to or within the invasive foamy gland
carcinoma. In these lesions, small or markedly dilated ducts were lined by cuboidal and columnar dysplastic nonfoamy cells and foamy cells. Hobnail cells were present in 2 cases. The PanIN-1, 2, and 3 lesions and the invasive foamy gland
adenocarcinomas stained with
mucicarmine,
periodic acid-Schiff, and
Alcian blue. The 3 PanIN-2 and -3 lesions and all 7 invasive foamy
adenocarcinomas labeled with CK7,
carcinoembryonic antigen polyclonal, and MUC1, whereas only 2 PanIN-2 and -3 lesions and 5 invasive
adenocarcinomas showed immunoreactivity for
cyclin D1 and p53. Three distinctive foamy PanIN lesions were identified within 7 invasive foamy gland pancreatic
adenocarcinomas. The gradual progression of cytological and architectural abnormalities of the PanIN lesions from PanIN-1 to PanIN-3 excludes neoplastic ductal spread. These foamy PanIN lesions probably represent
cancer precursors.