Incidence of cutaneous melanoma in the United States by histology with special reference to the face.

Cutaneous melanoma has been classified into three distinct histological subtypes based on histopathological and clinical features. The incidence of the least common type, lentigo maligna melanoma, has been most strongly associated with chronic sunlight exposure as its cause, especially lesions presenting on the face area. The relationship of sunlight exposure to the other two major subtypes, superficial spreading melanoma and nodular melanoma, is unclear. Based on over 13,000 cases of cutaneous melanoma collected by the Surveillance, Epidemiology, and End Results (SEER) program of the NCI, we report histological-specific incidence rates within four major anatomic sites: face, trunk, arm and shoulder, and leg and hip. The anatomic distribution for all histologies combined was the same as often reported with a male preponderance of melanomas on the face and trunk and female preponderance on the arm and leg. Age-specific incidence for melanoma of the face increased steadily with age in both genders, whereas it did not for the other three sites. The nine SEER areas were divided into North, Central, and South based on the UV index for each area. For melanomas of the face, lentigo maligna melanoma was higher in the Central and South than the North for both genders and increased with age. For superficial spreading melanoma, the pattern of occurrence was different. Incidence was higher in the Central than the North and for males it increased with age. There was a smaller increase for females. This study documents the incidence of cutaneous melanoma by histological subtype within four anatomic sites. The different shapes of the age-incidence curves suggest that different histologies may react differently to sunlight exposure as an etiological factor. Our findings strongly support the importance of considering histological subtypes of cutaneous melanoma in future etiological studies.