This study evaluates the potential usefulness of photodynamic therapy with PD P 506 A in patients with actinic keratosis on the upper extremities for the first time.

Patients will receive a second PD P 506 A-PDT on all AK lesions 1-2 weeks after the first PDT.

Inclusion Criteria:

• Written informed consent has been signed prior to or at Screening Visit
• Caucasian male and female patients
• Age ≥ 18 years
• Diagnosis of actinic keratosis (AK) with at least three locally separated lesions located on the upper extremities
• Selected AK study lesions have clearly defined margins and are mild to severe (grades I to III):
• Mild grade (I): Slight palpability, better felt than seen
• Moderate grade (II): Moderately thick AK, easily felt
• Severe grade (III): Very thick and/or obvious AK
• Skin sun sensitivity type I to IV according to Fitzpatrick

Exclusion Criteria:

• PDT Non-responder
• Pre-treatment of the AK lesions eligible for study procedures with pharmaceuticals approved for the treatment of AK during the 4 weeks preceding PDT (e.g. antineoplastic topical formulations as e.g. Metvix®, Ameluz®, Luxerm®, Solaraze®, Aldara®, Picato®, Actikerall®, 5-FU or vitamin A acid containing formulations)
• Pre-treatment of the AK lesions eligible for study procedures during the 2 weeks preceding PDT with keratolytic agents e.g. TCA, urea or salicylic acid containing formulations
• Pre-treatment with hypericin during the 2 weeks preceding PDT
• Treatment with systemic retinoids during the 3 months preceding PDT
• Treatment with cytostatics or radiation during the 3 months preceding PDT
• Female patients of childbearing potential (A female is considered of childbearing potential unless she has had tubal ligation, hysterectomy or has been postmenopausal, i.e. with spontaneous amenorrhea for at least 12 months.)
• Patients with clinically relevant suppression of the immune system
• Diagnosis of Porphyria
• Known photodermatoses of varying pathology and frequency, e.g. metabolic disorders such as aminoaciduria, idiopathic or immunological disorders such as polymorphic light reaction, genetic disorders such as xeroderma pigmentosum, and diseases precipitated or aggravated by exposure to sun light such as lupus erythematosus or pemphigus erythematosus
• Concomitant use of medicinal products with known phototoxic or photoallergic potential such as hypericin, griseofulvin, thiazide diuretics, sulfonylureas, phenothiazines, sulphonamides, quinolones and tetracyclines
• Skin diseases that might interfere with response evaluation of study PDT
• Skin sun sensitivity type V or VI according to Fitzpatrick
• Known intolerance to one or more of the ingredients of the study medication
• Dementia or psychic condition that might interfere with the ability to understand the study and thus give a written informed consent
• Simultaneous participation in another clinical study or participation in another clinical study in the 30 days directly preceding inclusion
• Suspected lack of compliance