Multiple primary melanomas: analysis of 49 cases.

Development of multiple primary melanomas is a rare but well recognized disease, with an estimated incidence ranging from 1.75% to 8.5% in several series. The clinical, histological and epidemiological characteristics of 49 patients, identified from 2470 with histologically confirmed melanoma, are described in this study. Thirty-five of these patients had two primary melanomas, 11 had three melanomas and three had four, five and six melanomas, respectively. Diagnosis was concurrent in 22 patients (45%); in the remaining cases the median time interval between the first and second melanoma was 22.6 months and the longest interval was 21.5 years. The mean Breslow's thickness decreased significantly (P < 0.001) from the first melanoma to the second and third lesion. The multiple melanoma patients had a higher percentage of subjects over 70 years of age or with lentigo maligna melanoma than single melanoma patients. The mean follow-up time was 12 years (range 4 23 years). The 5-year survival rate from first melanoma excision (83%) does not differ from that of patients with a single melanoma. In conclusion, the presence of multiple primary melanomas does not appear to be a negative prognostic factor; our data show the importance of close follow-up in melanoma patients in order to detect not only metastases, but also subsequent primaries in their earliest phases.