Fluorescence diagnosis and photodynamic therapy for Bowen's disease treatment.

Introduction: It has already been demonstrated the high efficacy of photodynamic therapy (PDT) for Bowen's disease (BD) treatment. Fluorescence diagnosis consists on registration of the fluorescence emitted by tissue after application of a photosensitizer, indicating presence of tumoral cells. It has been described as a useful tool for actinic keratosis. Different results have been published about fluorescence diagnosis for basal cell carcinomas. Very few reports about the role of fluorescence diagnosis for this entity exist and this is the first one which correlates the fluorescence image after PDT with the histopathological response.

Objectives: To assess the role of fluorescence diagnosis during BD follow-up.

Methods: We carried out an observational, retrospective and descriptive study. A total of 29 BD biopsy proven lesions were included. All the lesions had been treated with the standard protocol (Topical methyl- aminolaevulinic acid under occlusion for 3 hours and followed by illumination with red-light (630 nm, 38 J/cm(2), 7.5 minutes. Two sessions one week apart). Clinical and fluorescence photographs were taken before treatment and one month after the 2(nd) one. At that moment a post-treatment biopsy was performed. Clinical response was classified as partial, complete or no response. Fluorescence response was classified as negative, intermediate or intense. The follow-up period and the adverse events observed including pain were also collected.

Results: We found statistical association between fluorescence and the clinical and histopathological evaluations performed after treatment. Fluorescence diagnosis obtained a 100% sensitivity (higher than clinical evaluation alone) and a specificity of 85.7% (CI: 70.8-100).

Conclusions: Fluorescence diagnosis seems a valid diagnostic tool, useful during the follow up of Bowen disease lesions with the advantage of avoiding unnecessary post-treatment biopsies.