Seasonal presentation of keratoacanthomas in Rhode Island

Seasonal presentation of skin cancers has been previously described, but the seasonal presentation of keratoacanthomas is less well documented. Pathology reports and dermatology clinic visits were examined from the Roger Williams Medical Center, the major dermatopathology service in Rhode Island, U.S.A., from 1990 to 1992. Seasonal presentation was defined as the ratio of keratoacanthomas during the summer months (June-September) to the number diagnosed during the winter months (December-March). A peak incidence of keratoacanthomas was noted in the summer and early autumn months. The summer/winter ratio (1-38) was statistically significant (P = 0.002). The summer/winter ratio of office visits was smaller at 1.12, but also significant (P < 0.001). There appears to be a seasonal presentation of keratoacanthoma in southern New England. This suggests that ultraviolet radiation has an acute effect on the development of keratoacanthoma.