Abstract: Forty-six patients clinically diagnosed as arnelanoiic malignant or elanotnas (AMM) or suspected AMM were analyzed with anti-S100 protein, vixnentin, NSE, keratin, cytokeratin and CEA antilsodies by means of ABC method. Twenty-two patients diagnosed as pigmented malignant snelanamas (PAZM) were stained with the same methods as control.The results showed that 9 cases out of 33 patents clinically diagnosed as AMM and 13 suspected AMM did not accord with AMM in diagnosis, and one case out of 22 suspected PMM did not accord with PMM. The results suggest that using both anti-S100 protein and vimentin antibodies has an important value for the differerxtial diagnosis of AMM.

Key words: Melanoma, Isnmunohistochemistry