HISTOPATHOLOGIC STUDY OF RECURRENT CLARK LEVEL-II MELANOMAS

Overall, the prognosis for thin lesions of melanoma (less than 0.76 mm ) is excellent. However, a number of melanoma patients with seemingly innocuous lesions have been reported to develop recurrences. For this reason, we examined histologic sections taken from eight cases of Clar k level II melanoma that unexpectedly recurred, and compared their his topathologic features with an equal number of nonrecurrent lesions in whom reliable clinical follow-up data were available. Prognostic varia bles including Breslow thickness, mitotic rate, ulceration, the presen ce or absence of regression, a vertical growth phase component, and an associated banal nevus were evaluated in a double blind manner. When attempts were made to predict outcome based on one or more prognostic variables, the only correlation of statistical significance was the Br eslow thickness (P = 0.04). A Breslow thickness greater than 0.4 mm wa s associated with a significantly shorter disease free interval than a thickness below 0.4 mm. There was no significant correlation between predicted outcome based on the histologic features examined and the ev entual outcome based on history of recurrence (P = 0.36). These data i ndicate that although prognostic models that predict outcome in melano ma are generally reliable, there is a sizable population of patients w ith thin melanomas that do worse than would be expected.