Immunohistochemical studies of S100 protein and other neural characteristics expressed by granular cell tumour.

Eight cases of granular cell tumour (GCT), five Schwannomas and two neurofibromas were examined immunohistochemically for the presence of S100 protein, neurofilament protein (NP), epidermal growth factor (EGF) and glial fibrillary acidic protein (GFAP). The solochrome cyanin stain for myelin was also applied. All cases of GCT showed staining for S100 protein. Focal positivity was seen in Schwannomas and neurofibromas. Stains for EGF, GFAP, NP and solochrome cyanin were negative. S100 is a marker for Schwann cells. The expression by GCT of S100 supports a neural genesis of GCT.