The terms actinic and solar are from Greek and Latin, respectively, for ‘sunlight-induced’, and the term keratosis refers to thickened skin. Actinic keratosis (AK) are areas of sun-damaged skin found predominantly on sun-exposed parts of the body like the backs of the hands, forearms, the face and ears, the scalp in balding men and the lower legs in women. They may also occur on the lips. They are usually harmless but there is a very small risk of some actinic keratoses progressing to a form of skin cancer called Squamous cell carcinoma. AK’s are not contagious.
AK’s can vary in appearance. At first they can be hard to see, and are more easily felt, being rough, like sandpaper. They may grow to a centimetre or two in diameter. Some are skin coloured, others are pink, red or brown. They can become raised, hard and warty, and may even develop a small horny outgrowth. The surrounding skin often looks sun-damaged – blotchy, freckled and wrinkled.
Treatments used for AK’s include the following:
- Freeze Treatment with liquid nitrogen (Cryotherapy). This is an effective treatment which does not normally leave a scar, but it can be painful.
- Surgical removal. This requires local injection into the affected skin with anaesthetic, after which the actinic keratosis can be scraped off with a sharp spoon-like instrument (a curette), or it can be cut out and the wound closed with stitches. Surgical removal leaves a scar but provides a specimen that can be analysed in the laboratory to confirm the diagnosis.
- Creams. Courses of creams containing drugs which may include 5-fluorouracil, imiquimod or Ingenol mebutate gel are useful treatments for actinic keratoses, especially if there are many of them. These preparations appear to selectively destroy the abnormal cells in sun-damaged skin. However, they often cause a lot of temporary inflammation of the treated areas.
- Photodynamic therapy. A special light activates a cream which has been applied to the affected area of skin. This treatment is only available in certain hospitals.
Intra-Epidermal Carcinoma (AKA Bowen’s Disease & Squamous Cell Carcinoma In-Situ)
Squamous cell carcinoma in situ, often called Bowen’s disease, is a growth of cancerous cells that is confined to the outer layer of the skin. It is not a serious condition, and its importance rests on the fact that, very occasionally, it can progress into an invasive skin cancer known as squamous cell carcinoma. For this reason, dermatologists usually treat, or at least monitor Bowen’s disease.
A patch of Bowen’s disease starts as a small red scaly area, which grows very slowly. It may reach a diameter of a few centimetres across. It commonly occurs on sun-exposed skin, especially the face, scalp and neck, as well as the hands and lower legs. More than one area may be present. The development of an ulcer or lump on a patch of Bowen’s disease may indicate the formation of invasive squamous cell cancer.
Treatments are the same as for Actinic Keratoses.