Differential expression of cerbB3 in naevi and malignant melanomas

28 naevi, 43 malignant melanomas and 16 lymph nodes with melanoma metastases were stained immunohistochemically for the expression of cerbB3 oncoprotein. using antibody RTJ1. Positive reaction was found in 60% of naevi and in 25% of melanoma cases. The difference in frequency of the reaction occurrence between naevi and melanomas was statistically highly significant (p = 0.0017). In naevi, the percentage of cerbB3 positive cells (56.5%) was also significantly higher (p = 0.021) as compared with that of melanomas (37%). The cerbB3 positive cells were found only in cases without metastases. Positive reaction was also observed in 4 out of 16 investigated lymph nodes with melanoma metastases. The role of cerbB in the development of melanoma is discussed.