A Simultaneous Treatment Regimen Compared to a Sequential Treatment Regimen With Ingenol Mebutate Gel 0.015% and 0.05% of Two Areas With Actinic Keratosis on Face/Scalp and Trunk/Extremities

Inclusion Criteria:

* Subjects must provide informed consent
* Subjects with 4 to 8 clinically typical, visible and discrete AKs within a contiguous 25 cm2 treatment area on face or scalp
* Subjects with 4 to 8 clinically typical, visible and discrete AKs within a contiguous 25 cm2 treatment area on trunk or extremities
* Subjects at least 18 years of age
* Female subjects must be of either:

  1. Non-childbearing potential, i.e. post-menopausal or have a confirmed clinical history of sterility (e.g. the subject is without a uterus) or,
  2. Childbearing potential, provided there is a confirmed negative urine pregnancy test prior to trial treatment, to rule out pregnancy.
* Female subjects of childbearing potential must be willing to use effective contraception at trial entry and until completion.

Exclusion Criteria:

* Location of the selected treatment areas:

  * on the periorbital skin
  * within 5 cm of an incompletely healed wound
  * within 10 cm of a suspected basal cell carcinoma (BCC) or squamous cell carcinoma (SCC)
* Prior treatment with ingenol mebutate gel on face/scalp and on trunk/extremities
* Lesions in the selected treatment areas that have:

  * atypical clinical appearance (and/or,
  * recalcitrant disease
* History or evidence of skin conditions other than the trial indication that would interfere with the evaluation of the trial medication
* Use of cosmetic or therapeutic products and procedures which could interfere with the assessments of the selected treatment areas
* Clinical diagnosis/history or evidence of any medical condition that would expose a subject to an undue risk of a significant AE or interfere with assessments of safety and efficacy during the course of the trial, as determined by the investigator's clinical judgment.
* Anticipated need for hospitalisation or out-patient surgery during the first 15 days after the first trial medication application.
* Known sensitivity or allergy to any of the ingredients in ingenol mebutate gel
* Presence of sunburn within the selected treatment areas
* Current enrolment or participation in an investigational clinical trial within 30 days of entry into this trial
* Subjects previously randomised in the trial
* Female subjects who are breastfeeding
* In the opinion of the investigator, the subject is unlikely to comply with the Clinical Study Protocol

Prohibited Therapies and/or Medications within 2 weeks prior to Visit 1:

* Cosmetic or therapeutic procedures within 2 cm of the selected treatment areas
* Use of topical keratolytic therapeutic products within 2 cm of the selected treatment areas
* Use of topical medicated creams, ointments, lotions, gels, foams or sprays including topical steroids : within 2 cm of the selected treatment areas; artificial tanners: within 5 cm of the selected treatment areas

Prohibited Therapies and/or Medications: within 4 weeks prior to Visit 1:

* Treatment with immunomodulators, cytotoxic drugs or interferon/interferon inducers
* Treatment with systemic medications that suppress the immune system
* Treatment/therapy with ultraviolet light A (UVA) or ultraviolet light B (UVB)

Prohibited Therapies and/or Medications within 8 weeks prior to Visit 1:

\- Treatment with 5-fluorouracil (5-FU), imiquimod, topical diclofenac sodium, or photodynamic therapy within 2 cm of the selected treatment areas.

Prohibited Therapies and/or Medications within 6 months prior to Visit 1:

\- Use of systemic retinoids or biologic/monoclonal antibody therapies