An anatomical basis for prognosis of malignant melanoma.

Clinical observations during surgery have led us to speculate that an anatomic basis may in fact exist for the poor prognosis associated with malignant melanoma arising in certain recognized "high-risk" areas. In our study we have treated and followed 45 patients with primary malignant melanoma for over 5 years. During the course of treatment, we identified variations in anatomic characteristics at the tumor sites. Criteria were established for high- and low-risk locations by the neurovascular structure encountered. We speculate that these sites that have neurovascular windows provide a readily accessible vascular pathway for the dissemination of malignant cells to deeper visceral structures and may account for the poor prognosis associated with primary lesions in these locations. Thirty patients were classified as being at high risk for developing metastasis, whereas 13 were classified as being at low risk; 2 patients were in a special-risk category. To date, 12 of the 30 patients with "high-risk" melanoma have gone on to develop metastatic disease, which represents 40 percent of that group, whereas none of the patients classified as "low risk" have developed metastases during the same period.