Studies of the Melanocytes of the Epidermis Adjacent to Tumors

The incidence of basal layer melanocytes has been assessed in the epidermis overlying and adjacent to melanocytic and other tumors of and in the skin. The technique employed was direct counting of melanocytes in 6 μ vertical sections stained with hematoxylin and eosin. A summary of the author's work on the distribution of melanocytes in normal human epidermis and age, sex and site related frequency variations is included. A raised incidence of melanocytes was observed over primary malignant melanomas, compound nevi, juvenile melanomas and lentigos. The normal area incidence of melanocytes was noted in the epidermis over simple intradermal nevi, blue nevi, secondary malignant melanomas, secondary carcinoma in the dermis and most simple and malignant non-melanocytic epidermal tumors. Three abnormal patterns of melanocyte distribution were noted around malignant melanomas, symmetrical field change, asymmetrical field change and no field change. Patients with tumors arising in areas of field change had a better five year survival rate and less frequent hematogenous dissemination than those with no evidence of field change. The relevance of quantitative variations in melanocyte incidence to site distribution of malignant melanoma, the relationship of clinical 'lentigo' to histologically assessed melanocyte patterns, the histogenesis of the blue nevus and mechanisms of malignant transformation of melanocytes are considered.