Background: This is the first incidence report of keratoacanthoma (KA) in a Japanese ethnic population.
Methods: The study was designed as a 5-year prospective incidence study using an island-wide survey of Japanese residents in Kauai, Hawaii, during the years 1983 through 1987.
Results: Eleven Japanese residents of Kauai, three men and eight women, had KA. The crude incidence is 22.1 per 100,000 Japanese Kauaiian population. Two thirds of the lesions were on the extremities. No recurrence was noted, but a nonmelanoma skin cancer developed in some patients.
Conclusions: The incidence of KA in a Japanese ethnic population is not low. Ultraviolet light exposure must, in part, contribute to the development of KA. This is supported by fact that the incidence of KA in Japanese residents in Kauai is much higher than in Japan and that most of the KAS appear on exposed skin.