[Evaluation of immunochemistry staining in melanocarcinoma diagnosis]

Eleven cases of small cell tumor suspected of melanocarcinoma and another 10 cases of confirmed melanocarcinoma were studied with S-100, HMB-45, NSE and c-k antiserum staining. The main puzzling cells influencing to make a final diagnosis of melanocarcinoma by HE staining were those small cells similar to nevus cells and those round cells with abundant eosinophilic cytoplasm. Nevertheless, in both of them, there were no pigment obtained. In MF, S-100, HMB-45 and NSE staining, all of the 10 cases diagnosed as typical melanocarcinoma were positive except that one case was negative to S-100 and NSE staining. Among 11 suspicious cases, 8 were negative to MF (3 positive) and 9 cases were positive to S-100 and HMB-45 stains. The 2 negative cases left, anyhow, were positive to C-k staining which was finally confirmed as carcinoma rather than melanoma.