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Background: Electrocoagulation and laser evaporation for urethral condylomata acuminata have high recurrence rates and can be associated with urethral malformations. Objective: To investigate the effect of photodynamic therapy (PDT) with topical 5-aminolevulinic acid (ALA) on urethral condylomata acuminata and to examine the histological changes in lesions of condylomata acuminata after ALA-PDT. Methods: One hundred and sixty-four urethral condylomata patients were given topical ALA followed by intraurethral PDT through a cylindrical fiber. Among the cases, 16 penile and vulval condylomatous lesions in 11 patients were treated with topical ALA-PDT at same time. After the treatment, biopsy specimens were collected from the 16 penile and vulval lesions. The histological changes were then evaluated by light microscope and electron microscope. Results: The complete response rate for urethral condylomata by topical ALA-PDT was 95.12% and the recurrence rate was 5.13% after 6 to 24 months follow-up. Keratinocytes in middle and upper layers of the epidermis with marked vacuolation and some necrocytosis were detected one and three hours after PDT. Necrosis in all layers of the epidermis was noted five hours after PDT by microscopy. In electron microscopy of kerationcytes, distinct ultrastructural abnormalities of mitochondrion, endoplasmic reticulum and membrane damage were observed. Apoptotic bodies were detected three hours after PDT and a large number of the keratinocytes exhibited necrosis five hours after PDT by electron microscope. Conclusions: Results suggests that topical ALA-PDT is a simple, effective, relatively safe, less recurrent and comparatively well tolerated treatment for urethral condylomata acuminata. The mechanisms might be that ALA-PDT could trigger apoptotic process and necrosis in the HPV infected keratinocytes.
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