Controlled Study of the Occurrence of Actinic Keratosis on the Face After Cryotherapy + Aminolevulinic Acid (ALA) Photodynamic Therapy

Inclusion Criteria: * Four to fifteen AKs on the face * histologically confirmed presence of abnormal architecture and satellite atypical keratinocytes in the epidermis, in clinically normal tissue samples of photodamaged skin adjacent to AKs * at least one previously treated nonmelanoma skin cancer (NMSC) on the head and/or neck area within the past five years Exclusion Criteria: * Pregnancy * history of cutaneous photosensitization, porphyria, hypersensitivity to porphyrins or photodermatosis * lesions suspicious for skin cancer (skin cancer not ruled out by biopsy) or untreated skin cancers within the Treatment Area * skin pathology or condition which could interfere with the evaluation of the test product or requires the use of interfering topical or systemic therapy * Subject is immunosuppressed * unsuccessful outcome from previous ALA-PDT therapy * currently enrolled in an investigational drug or device study * has received an investigational drug or been treated with an investigational device within 30 days prior to the initiation of treatment * known sensitivity to one or more of the vehicle components (ethyl alcohol, isopropyl alcohol, laureth 4, polyethylene glycol) * has an active herpes simplex infection OR a history of 2 or more outbreaks within the past 12 months, on the face * use of the following topical preparations on the extremity to be treated: * Keratolytics including urea (greater than 5%), alpha hydroxyacids \[e.g.glycolic acid, lactic acid, etc. greater than 5%\], salicylic acid (greater than 2%) within 2 days * Retinoids, including tazarotene, adapalene, tretinoin, within 4 weeks * Microdermabrasion, laser ablative treatments, ALA-PDT, chemical peels, 5-fluorouracil (5-FU), diclofenac, ingenol mebutate, imiquimod or other topical treatments for AK within 8 weeks * use of systemic retinoid therapy within 6 months