This study was sought to evaluate the relationship between Her-2 protein
expression, cellular localization, gene amplification, and other
clinicopathologic parameters in colorectal carcinomas. Her-2 protein
expression and gene amplification were assessed in paraffin sections
from 106 primary colorectal adenocarcinoma cases using
immunohistochemistry and fluorescence in situ hybridization. Both
membranous and cytoplasmic immunostaining was evaluated. The results
were correlated with each other and with tumor grade, stage, and overall
survival. Membranous and cytoplasmic protein expression was identified
in 6 (5.6%) and 13 (12.26%) cases, respectively. Gene amplification
was detected in 4 (3.7%) cases. There was a high concordance between
membranous protein expression and gene amplification (kappa = 0.791). No
apparent association with any of the clinicopathologic parameters was
identified. Membranous Her-2 protein expression and gene amplification
are encountered in a small subset of colorectal carcinomas and are
highly concordant events. Cytoplasmic protein expression might be either
artifactual or it might represent a cross-reacting protein or a
precursor form of the mature protein
