Problems in microstaging of melanoma vertical growth.

Review of the currently available data would indicate that the measurement of tumor thickness in millimeters, especially those greater than 1.5 mm in thickness, is the single most important prognostic variable, closely followed by sex and location of the tumor. On the other hand, in thinner tumors, the level of invasion takes precedence over tumor thickness, especially in the setting of the "thin level IV" tumor. The microstaging must therefore include measurements of both level and thickness (keeping in mind the problems involved in thickness measurements noted above), as well as notation of special features of prognostic value (mitotic index, ulceration, microsatellites, etc.). Only with such refinements and the continued study of parameters from large databases can the estimates of prognosis in patients with primary malignant melanoma be made sufficiently accurate to be useful in planning appropriate therapy.