Immunohistochemical evaluation of uveal melanocytic tumors. Expression of HMB‐45, S‐100 protein, and neuron‐specific enolase

Abstract

The authors compared the immunohistochemical reactivity of 13 uveal nevi and 20 uveal melanomas for HMB‐45, S‐100 protein, and neuron‐specific enolase (NSE) in formalin‐fixed, paraffin‐embedded sections. All 33 of the lesions were positive for HMB‐45. The false‐negative rates for S‐100 protein and NSE were 21% and 18%, respectively. If only strongly positive reactions were considered, more than 50% of the tumors would be interpreted as negative for S‐100 protein and NSE. Nevi stained with less intensity than melanomas using all three antibodies. The expression of HMB‐45 appeared to be greater in active nevi than in inactive nevi. There was a weak association between S‐100 protein reactivity and the ability of the uveal melanomas to metastasize (P = 0.1); however, the standard deviation of nucleolar area was a much better predictor (P = 0.02). These results indicate that pathologists will find HMB‐45 to be a useful tool in differentiating uveal melanoma from nonmelanocytic tumors. Copyright © 1991 American Cancer Society