Immunohistochemical analyses were performed on 64 nevocellular nevi (12 compound 
nevi and 52 intradermal nevi). S-100 protein and its alpha- and beta-subunits 
were almost always demonstrated in type A, B and C cells, and the staining 
intensity tended to increase in the type C cells. Neuron-specific enolase was 
detected in each type of cell; however, the population of positive cells was 
smaller among type C cells. Beta 2-microglobulin was occasionally demonstrated, 
but only in type A cells. Vimentin was frequently revealed in every type of 
cell. Neither myelin basic protein nor glial fibrillary acidic protein was 
observed in any type of cell. In contrast, normal epidermal melanocytes were 
positive for vimentin, but negative for S-100 protein and its subunits and 
neuron-specific enolase. Schwann cells were positive for S-100 protein and its 
beta-subunit, but negative for the alpha-subunit. Thus, the nevus cells shared a 
common nature with epidermal melanocytes and Schwann cells which originate from 
the neural crest; however, the former cells were somewhat different from the 
latter two kinds and from benign and malignant tumors derived from these cells 
in the expression of these antigenic substances. Such differences in the 
expression of antigenic substances may be due to dysontogenic manifestations in 
nevus cells.