Clinical, histopathological and immunohistochemical evaluation of daylight photodynamic therapy in the treatment of field cancerization: a study of 30 cases.

Background: Actinic keratosis (AK) are pre-malignant lesions, precursors of squamous cell carcinoma (SCC). Normal skin adjacent to AK, may present initial mutations with potential risk for new neoplasms, currently known today as field cancerization (FC).

Objectives: To evaluate the effectiveness of daylight photodynamic therapy (PDT) with methyl amino levulinate (MAL) based on clinical evaluation, histological examination and immunohistochemical expression of p53 and Ki67.

Material And Methods: Thirty patients, over 35 years old, phototypes between I and III, presenting non-hypertrophic AK on the face or scalp. Two biopsies with 2 mm punch of the lesion and adjacent skin before and 60 days after daylight PDT were performed. Results: Improvement was seen in lesion thickness and Ki67. 19 (63.33%) lesions had atypia improvement with a -value <.05, showing efficacy in treatment. After daylight PDT, 22 (73.33%) patients showed satisfactory esthetic improvement.

Conclusion: The study shows that PDT has cellular and molecular effects that support its indication in the control of carcinogenesis, as it decreases atypia and controls the expression of Ki67, reducing the proliferation of atypical cells. However, its indication following this study is still mainly aimed at clinical improvement of the skin, at this moment, probably due to the sample size.