Solar lentigines are strongly related to sun exposure in contrast to ephelides

Solar lentigines and ephelides are different types of pigmented skin lesions predominantly present on sun-exposed skin. Both lesions are risk indicators for melanoma and non-melanoma skin cancer. Solar lentigines are considered as a sign of photodamage although well-conducted epidemiological studies are lacking on this subject. Ephelides are associated with fair skin type and red hair. The aim of the present study was to investigate the relation of sun-exposure estimates with solar lentigines and ephelides. In the Leiden Skin cancer Study 577 patients with malignant melanoma and/or non-melanoma skin cancer and 385 individuals without a history of skin cancer were studied. The presence of solar lentigines and ephelides in the face and on the back was assessed. Data on skin type, hair color, sun-exposure variables and cutaneous signs of photodamage were collected, by questionnaire and physical examination. Data were analyzed by chi-square or Student t-tests and with multivariable regression. Exposure odds ratios with 95% confidence intervals (95% CI) were calculated to estimate the relative risk for the presence of solar lentigines and ephelides dependent on signs of photodamage. The association with age was strongly positive for solar lentigines whereas it was strongly negative for ephelides (P-values for trend <0.0001). After adjustment for age, sex and skin type, solar lentigines on the back were positively associated with cumulative (P = 0.01) and intermittent (P = 0.0002) sun exposure. After adjustment, solar lentigines on the back were also associated with a history of sunburns before the age of 20 yr (P = 0.0003) and the number of sunburns in childhood (P = 0.002). Solar lentigines in the face were significantly associated with cutaneous signs of photodamage, i.e. elastosis (odds ratio 2.4, 95% CI 1.7-3.3) and actinic keratosis (odds ratio 1.8, 95% CI 1.3-2.4) whereas ephelides were not. Ephelides in the face and on the back showed an inverse association with chronic sun exposure but after adjustment theses associations disappeared. Sunburns before the age of 20 appeared to be positively associated with ephelides on the back (P = 0.04). In contrast to lentigines, ephelides were much more associated with constitutional host factors such as fair skin and/or red hair (both P < 0.0001). This study indicates that both chronic and acute sun exposure are important in the pathogenesis of solar lentigines.