Histological changes in facial skin after daily application of tretinoin for 5 to 6 years

Topical tretinoin was applied daily for 5 to 6 years to the face of seven type I Celts aged 60 to 69 years with marked heliodermatitis of the face. Before and after treatment, 4-mm punch biopsies were obtained and evaluated histo-chemically by light microscopy. Tretinoin corrected epidermal atrophy and atypia, with marked reduction in the density of melanosomes in the basal layer. A band of new collagen was laid down subepidermally, pushing downwards the old, degenerated elastotic material. Moreover, there was evidence of substantial resorption of amorphous elastotic material, along with formation of new reticulin. Glycosaminoglycans, abundant before treatment, were also reduced by tretinoin.