Comparison of HMB-45 monoclonal antibody and S-100 protein in the immunohistochemical diagnosis of melanoma.

The value of HMB-45 mouse monoclonal antibody in the immunohistochemical diagnosis of melanoma was compared with that of two antibodies to S-100 protein. Tissue from 32 (91.4%) of the 35 melanomas studied reacted with HMB-45, however, none of the 98 nonmelanoma tumors stained with this antibody. In contrast, 31 (88.5%) melanomas and 24 (24.4%) of the nonmelanoma neoplasms expressed S-100 protein. These results indicated that HMB-45 monoclonal antibody has a higher specificity for melanoma cells than did S-100 protein and that, because of its reactivity in routinely processed tissues, it may be helpful in surgical pathology.