SIZE OF THE JUNCTIONAL NESTS CAN PREDICT IN SITU MELANOMA BEHAVIOR

Abstract

In recent years, the diagnosis of in situ melanoma (MIS), has increased. Some authors have reported few isolated cases of MIS presenting recurrence, metastasis and death, however this unexpected behavior remains unexplained.Melanomas consisting exclusively or predominantly by large, irregular, atypical melanocytic junctional nests are consider, by some authors, righ risk lesions. We identified 445 cases of primary MIS in two hospitals of Rio de Janeiro state, between 1998 and 2010, reviewing the slides to classify them as nests in situ and other histopathological aspects. The results were correlated to the outcome. Eighteen cases presented almost exclusively by large irregular nests. Among these, we identified a patient who developed recurrence 61 months after the diagnosis. Five patients between the 427 cases presented recurrence and three developed regional metastasis. The correlation between the size of the largest junctional nest, and outcome was statistically significant. Although these rare cases of in situ melanomas with poor prognosis remains unexplained, we believe that the presence and size of expansive junctional nests must not be overlooked when the diagnosis of MIS is suspected.