Background: Photodynamic therapy (PDT) is an option for skin rejuvenation. Although many studies report clinical improvement with PDT in photodamaged skin, histologic and morphometric evidence is not documented in most cases.
Objective: To evaluate clinical and histopathologic changes induced by methyl aminolevulinate (MAL)-PDT and to morphometrically quantify collagen and elastic fibers in skin remodeling induced by MAL-PDT in photodamaged skin.
Methods and materials: Fourteen patients were treated with two sessions of MAL-PDT. The light source was a light-emitting diode: 635 nm, 37 J/cm(2). Skin biopsies were performed before and 3 and 4 months after treatment. All fragments were stained using the hematoxylin-eosin, orcein, and picrosirius techniques. Morphometric studies were done of three samples from each patient.
Results: Global clinical improvement was observed in 10 of 14 patients. The histopathologic study showed increased collagen fibers 3 and 6 months after treatment. The decrease in the amount of elastic fiber was statistically significant 3 (p=.016) and 6 (p=.008) months after treatment. The increase in the amount of collagen fiber was statistically significant 6 months after treatment (p=.048).
Conclusion: Clinical improvement with regard to texture, firmness, wrinkle depth, skin coloration, and clearance of actinic keratoses was observed. Histopathologic and morphometric studies were consistent with the clinical findings.