QUESTION 1 What is actinic keratosis? ANSWER 1 Actinic keratoses, also known as solar keratoses, are keratotic or scaling macules, papules or plaques resulting from the intraepidermal proliferation of atypical keratinocytes in response to prolonged exposure to ultraviolet radiation.1 They most commonly occur in older Caucasian populations with extensive photodamage. [...]of the complexity of the topical treatment, she was admitted to hospital. Other acute complications, although uncommon, include secondary infections.3 Chronic adverse events are also uncommon, but include persistent erythema, dyspigmentation and failure of treatment.4 Other regimens and treatments that can be employed to minimise side effects in this patient include: * small areas sequentially (eg just the forehead first and then the cheeks, or even smaller areas) * two days on, then five days off for 9-12 weeks2 * the four-day regimen combined with calcipotriol3 * pretreatment with daylight photodynamic therapy.1 This patient had a severe inflammatory response, causing crusting on her face, chest, arms and legs as a result of continuous, extensive application without monitoring.