Electron microscopic investigation on the local cellular reaction to primary malignant melanoma.

Five untreated primary malignant melanomas with relatively long duration have been investigated. Particular attention has been paid to the local cellular reaction observed in the intermediate zone lying between neoplastic and non-neoplastic tissue. Activated macrophages and histiocytes were seen as well as lymphocytes and lymphoid cells with cerebrifovm nuclei. Also, Langerhans cells were found in this zone and a close contact between these cells and melanophages was observed. The importance of the peritumoral cellular reaction in the local defence to neoplasma is discussed.