Immunohistochemical Demonstration of S-100 Protein in Meningioma

A total of 50 meningiomas was immunohistochemically examined for the presence of S-100 protein, an extremely acidic protein unique to the nervous system, by the peroxidase-antiperoxidase technique. Nineteen out of 50 meningiomas revealed unequivocally positive immunoperoxidase staining for S-100 protein. The distribution pattern of S-100 protein positive cells in these 19 meningiomas could be classified into three different types: diffuse (519), sparse (719) and clumpy (719) distribution of the positive cells throughout the sections. At present it is generally believed that S-100 protein is observed solely in the cells of either neuroectodermal or mesenchymal origin; therefore, the present immunohistochemical results strongly suggest that meningioma may consist of a variety of tumors with different histogenesis in terms of S-100 protein.