Clinical features and distribution of malignant melanoma and pigmented nevi on the soles of the feet in Japan.

This study, based on 842 cases of malignant melanoma from 108 medical schools and medical centers in Japan (from 1983 to 1985), presents information regarding the incidence, sex and age distribution, anatomical location, and clinical features of malignant melanoma in Japan and compares it with data from the United States. In the white population, the epidemiologic evidence indicates that exposure to sunlight may be an important causal factor of the disease. On the other hand, in more heavily pigmented races, such as Negroids and Orientals, many of the malignant melanomas occur on the skin of the unexposed soles of the foot. In our survey, 241 out of 833 cases of melanoma (28.9%) in Japanese patients involved the skin of the soles. Whites tend to have a wide distribution of cutaneous melanoma over the whole body surface, showing the greatest aggregation of lesions on the head, neck, and trunk, with small number on the soles of the feet. This comparative study revealed that the anatomical distribution and clinical types of malignant melanoma in the United States and Japan were different. The racial difference--the highest frequency or proportion of melanoma on the skin of the soles in the pigmented races, and the lowest ratio of this anatomical area in the least-pigmented races--remains to be investigated.