Photodynamic Therapy for Granuloma Annulare: More than a Shot in the Dark

Abstract

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/cm² 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.