The epidermal component of melanocytic naevi

Two hundred moles were examined histologically and the degree and type of epidermal change was recorded and correlated with the arrangement, density and type of naevus cells present and with the clinical presentation. Resemblances to the epidermal architecture of seborrhoeic warts were noted in 49% of the moles studied (this type of change was mainly seen in younger patients). In these there was a predominance of epithelioid cells, mainly in the junctional and upper dermal zones. Thirty-five per cent of moles possessed an epidermis with an overall appearance of being stretched, beneath which was a relatively clear zone followed by a uniform distribution of predominantly "lymphocytoid" naevus cells and large numbers of naevus cells of the giant type. These were found mainly in the older age groups. A third group (11%) was characterized by the presence of bulbous epidermal rete ridges and many junctional nests of naevus cells. This group was found mainly in younger age groups and there was often a history of recent change in the mole. It is concluded that the epidermal component of moles might itself be a naevoid disorder or result from the dermal disturbance induced by the mole cells.