[S-100 protein in non-pigmented melanocytic and neuro-ectodermal tumors of the conjunctiva].

Using an immunoperoxidase method, S-100 protein was localized in 51 nonpigmented or slightly pigmented nevi, eight malignant melanomas, three neurofibromas, and one neurilemmoma of the conjunctiva. Clinico-immunohistochemical correlations are presented. Cells of these neuroectodermal tumors contain S-100 protein. Epithelial invaginations arising from the conjunctival surface and lying between melanocytes are S-100 protein-negative. This facilitates the differential diagnosis of particularly amelanotic lesions of the conjunctiva. Immunohistochemical identification of the S-100 protein represents an improvement in current histochemical differential diagnosis of these tumors.