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

Abstract

The diagnosis of malignancy in pancreatic mucinous cystic tumors depends on demonstrating invasion that may be focal and require extensive sectioning. To explore markers that may indicate malignant potential in mucinous cystic tumors. 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 (EGFR), transforming growth factor alpha (TGF-alpha), and Ki-67. Expression of p53, HER-2/neu, and Ki-67 was significantly more frequent in mucinous tumors than in normal pancreatic tissue and chronic pancreatitis 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 EGFR were seen only in carcinomas. Coexpression of p53/HER-2/neu and EGFR/HER-2/neu and a frequency of Ki-67+ nuclei of greater than 5% of cells discriminated between mucinous tumors and normal pancreatic tissue and chronic pancreatitis tissue. p53 expression was significantly more frequent in carcinomas than in mucinous tumor (P =.0326). Coexpression of p53/EGFR discriminated between mucinous tumors and carcinomas; however, TGF-alpha was not discriminative. The immunostaining panel of p53, HER-2/neu, Ki-67, and EGFR can be helpful in indicating malignant potential in mucinous tumors of pancreas in routine pathology practice.