Lentigo maligna melanoma: epidemiology and prognosis.

Background. Lentigo maligna melanoma is a specific histoclinical type of me lanoma. We studied the epidemiologic features of lentigo maligna melanoma ( Dubreuilh's melanoma) and compared prognosis with other types of melanoma. Patients and methods. A retrospective review of 516 cases of cutaneous mela nomas, seen from 1985 to 1997, identified 29 cases of lentigo maligna melan oma. Epidemiologic, clinical and prognostic data were collected using a com mon scoring system for ail patients. The chi-squared test, univariate log r ank analysis, Cox multiple regression model For multivariate analysis, and actuarial survival curves were applied. Results. The 29 cases of lentigo maligna melanoma (16 women, 13 men) accoun ted for 5.9 p. 100 of all melanomas. Mean age at diagnosis was 73 years com pared with 54 years for others melanomas. Predominant localization was head and neck. There was no prior history of nevi compared with 50 p. 100. Mean delay to diagnosis was 4 years versus 1 year. All patients have had an occ upation with to sun exposure. Mean tumoral thickness was 2 mm. Survival was the same as for extensive superficial melanomas and better than for nodula r melanomas. Multivariate analysis showed that prognosis was not better in case of lentigo maligna melanoma. Tumoral thickness was the main prognosis factor. Discussion. Our findings confirmed the specific nature of lentigo maligna m elanoma and suggested that sun exposure plays an important role. Multivaria te analysis did not show that prognosis was any better in case of lentigo m aligna melanoma than in other types of melanoma. The thickness of the tumor must be taken into account as for other melanomas.