RESUMEN
<p><b>UNLABELLED</b>To investigate the expressions of fibrillin-1, elastin and matrix metalloproteinase-1 and -9 (MMP-1, 9) in chronic actinic dermatitis in elderly patients and explore the pathogenesis of the disease.</p><p><b>METHODS</b>Twenty-three patients with chronic actinic dermatitis were examined for the expressions of fibrillin-1, elastin, MMP-1, and MMP-9 with immunohistochemistry in the skin lesions. Image analysis was carried out to measure MMP-1 and MMP-9 expressions semi-quantitatively.</p><p><b>RESULTS</b>In the skin lesions of patients with chronic actinic dermatitis, elastin expression was obviously reduced or absent in the papillary dermis. The elastic fibers were disorderly arranged in the reticular dermis with local aggregation in some regions. Obvious fibrillin-1 deposition was found in the reticular dermis. Increased expressions of MMP-1, but not that of MMP-9, was found in the skin lesions of the patients.</p><p><b>CONCLUSION</b>Elastin and fibrillin-1 deposition can be found in the skin lesions in patients with chronic actinic dermatitis, suggesting the association of increased MMP-1 expression with the elastic tissue degeneration in the lesions. MMP-9 does not exhibit an obvious association with the pathogenesis of chronic actinic dermatitis in elderly patients.</p>