Chronic solar dermatosis--an electronmicroscopic study of the epidermis.

Abstract

Summary The epidermis from six cases of chronic solar dermatosis (three from the face, and three from the neck), has been examined with the electronmicroscope. There is electronmicroscopic evidence of reduced protein and lipid reserves in the keratinocytes, and of decreased keratin formation. These changes are believed to be caused by poor nutrition as a result of the ultraviolet light-induced changes in the dermis. There is no indication that the keratinocytes. are affected directly by the ultraviolet light. Some melanocytes are large and hyper-functional, probably due to ultraviolet light stimulation, but many are hypo-functional with few or no melanosomes, few cellular organelles, and frequently a deeply indented nucleus. It is considered likely that the ultraviolet light filtering ability of the epidermis is reduced in chronic solar dermatosis because there is less keratin in the stratum corneum and many melanocytes are incapable of producing melanin. Therefore, once chronic solar dermatosis is established, it would predispose to the development of ultraviolet light induced cancers.