Gene Expression in Renal Transplant Patients With Field Actinic Keratosis Undergoing Metvix® Photodynamic Therapy (PDT)

Inclusion Criteria: * Renal transplant with an history of immunosuppression from 5 to 15 years, * Presenting at least 4 discrete AK lesions, mild or moderate, either on the face, the scalp, forearms or the chest. Exclusion Criteria: * At risk in terms of precautions, warnings, and contra-indication referred in the package insert of Metvix®, * AK lesions clinically atypical or suspicious for malignancy on the target field, * Any of the following topical treatments within the specified washout period at Screening: * 5-FU, Imiquimod, Diclofenac sodium: 3 months, * Cryotherapy: 3 months, * PDT: 3 months, * Other less common AK treatments: 3 months. * Systemic retinoids within the last month prior to Screening visit.