A Geo-Pathological Study on Malignant Melanoma in Japan

Two hundred and twelve autopsied cases of malignant melanoma observed in Japan were studied as to incidence, primary sites, and mode of metastases, mainly from the point of view of geographic pathology. The overall incidence among all autopsy cases was 0.16%. Malignant melanoma in Japan seems to have some specific features such as: (1) a relatively low incidence of cutaneous and a relatively high incidence of non-cutaneous melanoma; (2) lower extremities, especially the sole of the foot, being the primary site of predilection of cutaneous melanoma; and (3) high incidence of mucosal melanomas including those of nasal, paranasal, and oral cavities, the latter being more common in females than in males. These findings are similar to those observed among other colored populations and differ from those noted in Caucasians. The higher incidence of the tumor in the less sunny part of Japan suggests that the role of sunlight in the causation of melanoma is still a moot question.