Low- and high-risk malignant melanoma--I. Evaluation of clinical and histological prognosticators in 585 cases.

In 585 cases with primary cutaneous stage I malignant melanoma (294 disease-free for at least 5 yr, 291 with later metastases) prognostic parameters were examined. The most effective proved to be tumor thickness and mitotic activity, particularly when combined as a prognostic index. Furthermore, vascular invasion, ulceration in thick tumors (thickness greater than or equal to 3.0 mm), severe cellular atypia, the small, lymphocytic-like cell type and the absence of an inflammatory reaction were closely associated with a high rate of metastatic cases. Less relevant prognostic factors were the level of invasion, sex, site, tumor breadth, clinical diameters and infiltrative growth. Tumor type, age, duration and an adjacent nevocellular nevus were not significantly associated with the occurrence of later metastases. Furthermore, the growth-type (exo- or endophytic) did not have a bearing on the prognosis.