Inclusion Criteria:

- Out-Patients of either sex aged ≥ 40 years

- Life-expectancy of 2 years at minimum

- Solid organ-transplant recipients who received a kidney (including pancreas), liver,
lung, or heart transplant

- Patients treated for 5 years with an immunosuppressant medication

- Severe sun damage of the skin

- Multiple actinic keratoses (2-5 lesions) and/or multiple dysplastic naevi

- No present squamous cell carcinoma, basal cell carcinoma or malignant melanoma; but
history of cutaneous/cutaneous invasive malignancy with restitutio ad integrum is
allowed

- Patients who are able to understand and provide written informed consent to
participate in the clinical trial (signed informed consent) according to ICH GCP

Exclusion Criteria:

- Non-Caucasian

- Absence of sun damage i.e. no signs of AK

- Multi-organ transplantation (exception: simultaneous transplantation of kidney and
pancreas)

- Evidence of systemic infection, except viral hepatitis, at the time of recruitment

- Known or supposed systemic malignant tumour or systemic chemotherapy within the last
5 years prior to randomisation

- Patients participating in a clinical trial within the last four weeks before trial

- Patients treated with the antitumour/antiangiogenetic immunosuppressant sirolimus,
respectively everolimus, or acitretin or any other systemic treatment for AK at the
time of randomisation

- Patients treated with a topical drug for the AK at the time of randomisation
(exception: excision or kryotherapy for hyperkeratotic lesions are allowed)

- Change of the immunosuppression-treatment less than 3 months ago or planned

- Present or planned interferon therapy (in liver transplant patients with hepatitis
B/C)

- Female patients with childbearing potential with a positive pregnancy test, breast
feeding, or female patients with childbearing potential without adequate
contraception