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SF | CPD: DERMATOLOGY
May 2021 | Vol. 21 No. 5
This article was independently sourced by Specialist Forum.
www.medicalacademic.co.za
Management in clinical practice of MULTIPLE MULTIPLE face and scalp AK
Actinic keratoses (AKs) are one of the top three most common skin disorders seen in clinical practice. AKs, also known as solar keratoses, are caused by long-term sun exposure, and about 75% of all reported lesions present on the head, neck, and forearms.1,2,3,5
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revalence rates range from 24%60%. Population‐based data from the Rotterdam Study and the Australian Skin Cancer Cohort estimate that 24% (the Netherlands) to 60% (Australia) of people older than 50 years have at least one AK.1,3,5,7 Prevalence rises with age and peeks between the ages of 70 and 80. Apart from excessive exposure to ultraviolet radiation (UV) and age, other risk factors include phototypes I and II (see box 1), previous history of cutaneous neoplasms and male gender.1,3,5,7 The prevalence of AKs is increasing worldwide, partly due to environmental factors, such as thinning of the ozone layer and more UV radiation. Other factors include lifestyle choices such as increased tanning (outside and sunbed). 2 Despite the high prevalence of AKs, there seems to be a lack of awareness among the general public and primary care physicians about the potential consequences of the condition. AKs are often a pre-cursor to squamous cell carcinoma (SCC) and basal cell carcinoma (BCC).1,7 Patients do not necessarily seek care for asymptomatic AKs and often only seek medical care when they have more than one lesion. Primary care physicians are often not aware of
the different treatment modalities for AKs due to a lack of dermatological training.7 In resource limited countries with only a few trained dermatologists, primary care physicians then become the gatekeepers to specialist care. Several international bodies, including the United States Preventative Services Task Force, stress that appropriate awareness campaigns about AKs and its treatment should be undertaken among the general public as well as primary care physicians, and primary care AKs guidelines are essential.7 The Netherlands (2015) took the lead in publishing AKs guidelines directed at primary care physicians, followed by the British Primary Care Dermatology Society (2020).7,9
What do AKs look like? AKs present as macules, papules, or plaques with superficial scales on a red base, which are classified based on histological features. They may also be pigmented and show variable degrees of infiltration. A single AK lesion may have one of three possible outcomes:8 It can enter spontaneous remission
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Remain stable without further progression
Transform over time into in situ or invasive carcinoma. When lesions multiply, they lead to field cancerisation, a process in which a singular cell accumulates genetic mutations following carcinogen exposure and then divides to create a field of monoclonal premalignant cells.1,2,5,6 The field starts from a single stem cell. The stem cell then undergoes one or more genetic changes, which allows it to grow. The stem cell then divides, forming a patch of clonal daughter cells, which displace the surrounding normal epithelium.6 This growth eventually leads to a dysplastic field of monoclonal cells. No invasive growth or metastases are visible yet but over time, continued carcinogenic exposure (eg ultraviolet radiation [UV]) causes additional genetic alterations among different cells in the field. If left untreated, this leads to new subclonal proliferations, eventually forming a carcinoma. Patients with more than five AKs are at high risk of SCC. The likelihood of AKs progressing to SCC ranges between 0.025% and 16% per year, and it is an accumulative risk over years, eg 0.6% at year one, and 2.6% at year four. 4,5,8
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How are AK diagnosed? Although the diagnosis of AKs is based on