Metastases of thin melanomas.

Although thin malignant melanomas, i.e., those less than 0.76 mm in thickness, of the skin generally do not metastasize, it has been recently reported that when histologic regression is present, such lesions may then have a greater propensity for dissemination. However, this was not apparent in this study in which only one melanoma metastasized in a consecutive series of 41 thin lesions which were step-sectioned and had evidence of regression histologically. Possible explanations for this discrepancy are the failure of other authors to include only step-sectioned specimens of the primary melanomas in their material and/or geographic differences in the biologic behavior of this malignant neoplasm.