Skin lesions suspected to be melanoma should be photographed. Gross morphological features of primary melanoma associated with metastases.

We reviewed photographs of 256 primary cutaneous melanomas to determine the gross morphological correlates of metastases. Seven and a half years after diagnosis, the melanomas with ulceration occupying at least 80% of their surface had the highest rate of metastases (85%), and melanomas without a nodule had the lowest metastatic rate (11%). Melanomas with nodules had a metastatic rate of 62%, and this rate increased in direct proportion to nodule diameter. Even after adjusting for nodule diameter and ulceration, melanomas with single nodules located completely within the confines of an associated plaque had half of the metastatic rate of melanomas with nodules located at the periphery (abutting normal skin). These data suggest that (1) carefully recorded gross pathological data can augment the microscopic pathological data in the determination of prognosis; (2) skin lesions suspected to be melanoma should be photographed; (3) the photograph, if followed by surgical removal of the lesion, should be attached to the pathology report in the patient's permanent medical record; (4) nodule diameter is better correlated with metastases than the total lesion diameter (as traditionally held); and (5) the cytologically malignant melanocytes that constitute the less-raised portion of most melanomas may not be biologically malignant, thus enlarging the precursor concept for malignant melanoma. The TNM staging system for malignant melanoma could be modified to incorporate these data.