An immunostaining panel for diagnosis of malignancy in mucinous tumors of the pancreas

Background - The diagnosis of malignancy in pancreatic mucinous cystic tumo rs depends on demonstrating invasion that may be focal and require extensiv e sectioning. Objective - To explore markers that may indicate malignant potential in muc inous cystic tumors. Design - Routinely processed sections from resected specimens of 12 normal pancreata, 14 pancreata with chronic pancreatitis, 9 mucinous cystic tumors , and 30 invasive adenocarcinomas were immunostained with antibodies to p53 , HER-2/neu, epithelial growth factor receptor (ECFR), transforming growth factor alpha (TCF-alpha), and Ki-67. Results - Expression of p53, HER-2/neu, and Ki-67 was significantly more fr equent in mucinous tumors than in normal pancreatic tissue and chronic panc reatitis tissue (P = .0003 to .05). Strong expression (more than one third of cells positive) and strong intensity (2+ and 3+) of staining of p53 and ECFR were seen only in carcinomas. Coexpression of p53/HER-2/neu and EGFR/H ER-2/neu and a frequency of Ki-67+ nuclei of greater than 5% of cells discr iminated between mucinous tumors and normal pancreatic tissue and chronic p ancreatitis tissue. p53 expression was significantly more frequent in carci nomas than in mucinous tumor (P = .0326). Coexpression of p53/EGFR discrimi nated between mucinous tumors and carcinomas; however, TCF-alpha was not di scriminative. Conclusions - The immunostaining panel of p53, HER2/neu, Ki-67, and EGFR ca n be helpful in indicating malignant potential in mucinous tumors of pancre as in routine pathology practice.