RESUMO
<p><b>OBJECTIVE</b>To observe the efficacy of 5-aminolevulinic acid photodynamic therapy (ALA-PDT) for treating psoriasis vulgaris in guinea pigs.</p><p><b>METHODS</b>Experimental psoriasis vulgaris was induced in guinea pigs by application of 5% propranolol on the ear skin. After dressing of the skin lesion with 20% ALA solution for 4 h, the lesions were irradiated with a semiconductor laser at the wavelength of 635 nm and energy density of 12 J/cm(2). The guinea pigs were divided into control group, ALA only group, light only group, single ALA-PDT treatment group and twice ALA-PDT treatment group. In each group, gross observation and biopsy of the skin lesions was conducted on days 7, 14, 21 and 28 after the treatment.</p><p><b>RESULTS</b>In terms of gross observation of the lesion, epidermal thickness and proliferating cell nuclear antigen (PCNA) expression, ALA-PDT treatment showed obvious therapeutic effect on the skin lesion, and two treatment sessions resulted in better effect than a single session.</p><p><b>CONCLUSION</b>ALA-PDT can cure psoriasis vulgaris lesions characterized by abnormal epidermal proliferation in guinea pigs, and multiple treatment sessions can achieve better effects.</p>