Actinic keratoses develop due to DNA damage from repeated ultraviolet exposure (eg. sunlight) resulting in abnormal epidermal cells. They are also known as solar keratosis and are commonly abbreviated as AK or SK. Actinic keratoses can be thought of as being on a continuum of:
- Actinic keratosis (AK): most superficial.
- Squamous cell carcinoma in situ (SCCis) / intraepidermal carcinoma (IEC): limited to the epidermis.
- Squamous cell carcinoma (SCC): involves the dermis.
Not all AKs progress into SCCs and an individual AK develops into SCC at a rate of about 0.5-2% per year. However, when people have hundreds of AKs on their body this can result in the development of several SCCs. It is also an indicator that the skin has chronic sun damage and the potential for cellular damage that is not visible.
Actinic keratoses can resolve spontaneously (without treatment) and it is thought this may be encouraged by rigorous sun protection. However, they can also recur after having seemingly disappeared.
Appearance of actinic keratosis
Actinic keratoses are characteristically described as small, crusty, scaley, or rough lesions that are typically skin coloured. Some can be painful; however, they are most commonly asymptomatic. People can have hundreds of AKs on their body but they are most common on repeatedly sun-exposed areas such as the face, head, and hands.
When there are several actinic keratoses in an area it is often referred to as actinic field damage.
Treatment of actinic keratosis
There are several different treatment options for actinic keratoses. Your dermatologist will discuss with you the various treatment options and consider the best options for your situation.
Single lesions are commonly treated with liquid nitrogen (freezing) which can be done during the consultation. It is normally quick and reasonably cheap. It is typically performed as a single treatment and usually heals well within several days.
Other options include:
- Fluorouracil (Efudix) treatment: a prescription cream that is applied over a course of 5 days to 6 weeks.
- Imiquimod (Aldara) treatment: an alternative cream for those who are unable to use fluorouracil, however, it is less effective.
- Curettage & cautery (C&C) is a minor surgical procedure which is particularly useful for large or thick actinic keratoses.
Actinic Field Treatment
When there are numerous lesions in an area (field damage) the sun damage is extensive. Numerous visible lesions are often accompanied by extensive cellular damage that is not visible. Many of these damaged cells are likely to develop into (visible) actinic keratoses.
As such, it is often best to treat as a field/region – what is referred to as actinic field treatment. By far the most effective option for this is fluorouracil cream (Efudix). We discuss actinic field treatment in detail separately.
AKs are early pre-cancerous lesions and don’t spread (metastasise); however, if they are left untreated they can progress to squamous cell carcinoma (SCC).
AKs can recur after treatment.
- Criscione, V. D., Weinstock, M. A., Naylor, M. F., Luque, C., Eide, M. J., & Bingham, S. F. (2009). Actinic keratoses. Cancer, 115(11), 2523-2530. doi: 10.1002/cncr.24284