[Cutaneous melanoma associated with previous nevus]

The malignant melanoma is a neoplasia originated from the melanocytes located in the skin and other locations. Even though there is not information regarding its incidence and prevalence in our country, its most important risk factors are known. The melanoma can originate de novo or from previous melanocytic lesions. The concept that a melanocytic nevus can serve as a precursor lesion is supported by clinical and histological evidence. An observational, retrospective and analytical study was carried out in the Hospital Privado de Córdoba. The objective was to determine which is the frequency of association of malignant melanomas that develop on previous nevus. A total of 134 melanomas were analyzed. In 32 cases (24%), the melanomas were histologically associated with nevus, in individuals with Breslow's depth bigger than 1 mm the percentage of association was 16.3% while in those exhibiting Breslow smaller than 1 mm the percentage of association was 38.1%. Having evaluated the melanomas in relation to the Breslow and Clark classification, we observed that the nevus associated melanoma group showed less Breslow thickness and low Clark levels, which, by statistical analysis were shown to be significant predictors of the probabilty of finding this association (p < 0.027). This study demonstrates that the tumor thickness by itself is an independent predictive factor of the association melanoma-nevus. However, the rest of the variables studied did not throw significant results from the statistical point of view. In conclusion, patients must be educated for the control of new pigmented injuries as well as for the modification of preexisting nevi.