Monoclonal S-100 immunocytochemistry of pigmented naevi with tactile-like corpuscles

We examined 12 cases of pigmented naevi with tactile-like corpuscles by immunohistochemistry using polyclonal and monoclonal antibodies against S-100 protein. Naevus cells, the tactile-like corpuscles, and the attached lamellae and fibroblastic cells gave a strong reaction with S-100 protein and the beta-subunit antibodies. The same cells gave only a weak reaction with the alpha-subunit antibody with the exception of about 4 per cent of corpuscles and 1-1.5 per cent of naevus cells, whether pigmented or not, which gave a strong reaction with this antibody. These results suggest that the non-pigmented naevus cells and the constituent cells of the corpuscles are closely related and the latter might derive from the former by organoid differentiation.