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Updated: Jun 30, 2026
An In Vitro Approach to Photodynamic Therapy
Published on: August 17, 2018
Photodynamic therapy for granuloma annulare: more than a shot in the dark
Peter Weisenseel1, Alexander Vasilevic Kuznetsov, Sonja Molin
1Department of Dermatology, Ludwig Maximilian University, Munich, Germany. peter.weisenseel@med.uni-muenchen.de
Background:
Granuloma annulare (GA) is a benign granulomatous and inflammatory skin disorder. The pathogenesis remains enigmatic and convincingly effective treatment options are not available. Inspired by a report showing photodynamic therapy (PDT) to be effective in a single patient with GA, we sought to evaluate this benefit in a series of patients with GA.
Observations:
PDT was performed in 7 consecutive patients with histologically confirmed GA located at the extremities. First, 20% ALA gel was applied under an occlusive dressing for 5 h, followed by illumination with 100 J/cm(2) by a standard red-light source. In total, 2-3 PDT sessions were performed, with an interval of 2-4 weeks between each session. Treatment was stopped when complete remission was achieved or when GA lesions remained unchanged after 2 consecutive PDT sessions. The overall response rate was 57%. In 2 patients (29%), GA cleared completely, in 2 patients (29%) the skin lesions improved markedly and in 3 patients (43%) no clinical response could be observed.
Conclusion:
These promising results should be evaluated in larger controlled studies. In selected patients, PDT might be a valuable recruit for the sparse armory available to treat GA.
