[Immunohistologic differential diagnosis of skin tumors in routinely embedded paraffin sections]

Thirty-nine skin tumors of epithelial, mesenchymal, and neuroectodermal origin were studied using antibodies against intermediate filaments and other cell proteins. Formol-fixed and paraffin-embedded material was reconstituted and stained with antibodies against epithelial cells (keratin, epithelial membrane antigen, carcinoembryonic antigen), mesenchymal and histiocytic cells (vimentin, alpha-1-antichymotrypsin, alpha-1-antitrypsin, lysozyme), nerve tissue (neurofilament, glial fibrillary acidic protein, myelin basic protein, myelin-associated protein, neuron-specific enolase), vessels (factor-VIII-related protein), basal cell lamina (laminin) and S-100 protein. Tumor cells displayed the same antibody pattern found in the normal cell type. It is recommended that immunotyping be started with three antibodies to allow gross classification into epithelial (keratin positive), mesenchymal (vimentin positive) and neuroectodermal (vimentin and S-100 protein positive) tumors; then, in a second step, the tumors can be subclassified by the other more specific antibodies listed above. All antibodies used in this study are commercially available and provide reliable results.