Evaluation of pancreatic intraepithelial neoplasia and mucin expression in normal pancreata

Abstract

Background/purpose: It has been suggested that pancreatic ductal adenocarcinoma (PDAC) and pancreatic intraepithelial neoplasia (PanIN) are closely related, but several reports indicate PanIN lesions can also be found in normal pancreata (normal PanINs). We examined differences in mucin expression between normal PanIN lesions and PanINs in PDACs (PDAC PanINs).

Methods: We examined 54 autopsied normal pancreata and eight autopsied PDACs for PanIN lesions; graded the pancreata specimens as PanIN-1A (non-papillary hyperplasia), PanIN-1B (papillary hyperplasia), PanIN-2 (atypical hyperplasia) or PanIN-3 (carcinoma in situ); and tested the PanIN lesions for expression of MUC1 (pan-epithelial membrane-associated mucin) and MUC5AC (gastric secretory mucin) which were both previously detected in PDACs.

Results: In normal PanIN-1A, PanIN-1B and PanIN-2 specimens, MUC1 was expressed in 2.8, 10.5 and 9.1%, respectively, compared to 19.1, 27.6 and 13.0% in PDAC PanIN-1A, PanIN-1B and PanIN-2 specimens, respectively. MUC5AC was expressed in 41.0, 65.7 and 36.4% of normal PanIN-1A, PanIN-1B and PanIN-2 specimens, respectively, and in 80.9, 75.8 and 78.3% of PDAC PanIN-1A, PanIN-1B and PanIN-2 specimens, respectively. Differences in the frequency of MUC1 expression were significant between normal and PDAC PanIN-1A (p < 0.0001) and PanIN-1B (p < 0.05); and differences in the frequency of MUC5AC expression were significant between normal and PDAC PanIN-1A (p < 0.0001) and PanIN-2 (p < 0.05).

Conclusions: Normal PanIN and PDAC PanIN lesions differed in the rates of MUC1 and MUC5AC expression.