Epidermal growth factor receptor is not amplified in schwannomas

Epidermal growth factor receptor (EGFR) is a tyrosine kinase receptor of the ErbB family. This family of receptors plays an active role in cellular growth and mitogenesis. It is well established that the overexpression of ErbB receptors in human cancers, most commonly because of true genomic amplification, correlates with a more aggressive clinical course. There is limited data published on the expression and amplification of EGFR in schwannomas. Both neurofibromas and schwannomas are capable of progression to malignant peripheral nerve sheath tumors (MPNSTs). A subset of human MPNSTs, both NF-1-related and sporadic, overexpress EGFR via true genomic amplification of the short arm of chromosome 7 (7p12). The goal of this study is to assess whether EGFR is expressed and/or amplified in human schwannomas. Twenty schwannomas in 12 women and 8 men (mean age, 51 years) were analyzed for EGFR expression via immunohistochemistry and fluorescence in situ hybridization. None of the 20 cases were positive for EGFR expression via immunohistochemistry; 3 tumors showed focal nonspecific Golgi staining. None of the cases demonstrated true genomic amplification of the EGFR region via fluorescence in situ hybridization. The mitogenic signaling for schwannomas is unlikely to be related to overexpression or amplification of EGFR; however, acquiring this signaling pathway might contribute to the progression of a subset of benign peripheral nerve sheath tumors to MPNST.