Background  Condyloma acuminatum is a sexually transmitted disease caused by human papillomavirus infection. The male urethra has a special physiological and anatomical structure, thus it is difficult to remove condyloma acuminatum in the urethra by traditional freezing and laser treatment. Photodynamic therapy is suitable for the treatment of condyloma acuminatum in urethra due to its small damage and good repeatability. At present, the commonly used drug delivery method of photodynamic therapy is to soak the cotton swab in the drug gel, fill the cotton swab into the urethra and make wet compress for the wart.

  Objective  To observe the effect of 5-aminolevulinic acid photodynamic therapy (5-ALA-PDT) with thermosensitive gel as matrix injected into urethra for treatment of condyloma acuminatum in male urethra.

  Methods  From January 2016 to December 2020, patients with urethral condyloma acuminatum were randomly divided into thermosensitive gel injection group and thermosensitive gel cotton swab wet compress group. In the injection group, 20% of 5-aminolevulinic acid based on thermosensitive gel was directly injected into the urethra at a suitable depth (1 cm deeper than the wart), and the drug was maintained for 3 hours; In the cotton swab wet compress group, 20% of 5-ALA cotton swabs with thermosensitive gel as the matrix were filled into the affected area and around the 1 cm range of urethral with wet compress for 3 hours; Both the two groups were irradiated with 635 nm semiconductor laser, with the energy density between 100-120 J/cm², the irradiation time of 20-30  min/spot and the correction power was 80mw/cm². All patients were treated once every 7-10 days for 3-5 times continuously. After 10 days, one month and three months of treatment, the complete clearance rate, recurrence rate and side effects in the two groups were observed. Results Totally 44 patients were enrolled, with 22 cases in each group. The patients aged 29.3 ± 6.3 (range, 19-42) years in the thermosensitive gel injection group, and 30.1 ± 7.3 (range, 19-44) years in the thermosensitive gel cotton swab wet compress group (P＞0.05). Follow up lasted for 3 months. The complete clearance rate of the thermosensitive gel injection group and the thermosensitive gel cotton swab wet compress group was 86.3% and 72.7% after 3 times of treatment (P=0.457), and 95.5% and 90.9% after 5 times of treatment (P=1.000); The recurrence rate was 9.5% and 10% (P=1.000). After treatment, there was mild to moderate urination pain and occasional slight itching, and the pain was milder in the thermosensitive gel injection group. No systemic adverse reactions occurred.

  Conclusion  5-ALA-PDT by injecting the thermosensitive gel into urethra as the photosensitizer carrier is effective, economical and comfortable for the treatment of male urethral condyloma acuminatum, which is worthy of clinical generalization.