Human peripheral nerve sheath neoplasm: expression of Schwann cell-related markers and their relation to malignant transformation.

We immunohistochemically examined the expression of Schwann cell-related markers, nerve growth factor (NGF) receptor, S-100 alpha- and beta-proteins, glial fibrillary acidic protein (GFAP), and galactocerebroside (gal C) in 5 malignant schwannomas, 21 benign peripheral nerve sheath tumors, and 4 apparently normal sural nerves. NGF receptor was expressed in the malignant schwannomas and benign peripheral nerve sheath tumors, but not in the endoneurium of apparently normal peripheral nerves. S-100 alpha-protein was observed in malignant schwannomas and in some neurofibroma cells. All cases were strongly positive for S-100 beta-protein but were negative for GFAP and gal C. Our results suggest that these Schwann cell-related markers may be useful in identifying peripheral nerve sheath neoplasma as well as their malignant transformation.