Differential expression of epidermal growth factor receptor in melanocytic tumours demonstrated by immunohistochemistry and mRNA in situ hybridization.

Abstract

Differential expression of the epidermal growth factor receptor (EGFR) has been reported in melanocytic lesions. To evaluate these differences in EGFR expression in melanocytic tumours, formalin-fixed, paraffin embedded sections from 33 benign melanocytic neoplasms and 77 cutaneous melanomas were analysed for EGFR protein and mRNA expression using immunohistochemistry and mRNA in situ hybridization. The majority of benign and malignant lesions expressed EGFR at both protein and mRNA levels. In 7% (7/100) samples, mRNA but not protein expression was observed. Overall, a higher proportion of cells expressed EGFR protein in malignant lesions compared with benign lesions (P = 0.06), and the intensity of mRNA expression was higher in the malignant tumours (P < 0.001). No significant differences in EGFR protein or mRNA expression with tumour progression within the malignant lesions were seen. These results indicate that EGFR mRNA and protein expression is common to benign and malignant melanocytic lesions, and that an overall increase in expression is associated with malignant transformation. However, differential EGFR expression between in situ melanomas and invasive or metastatic lesions was not observed.