What is solar keratosis?

Solar keratosis, also known as actinic keratosis, is a condition where patches of skin can become rough and scaly caused by exposure to ultraviolet (UV) light. These skin changes are not cancerous, but there is a small risk that they can become squamous cell carcinoma.

Cancerous

Pertaining to cancer, a disease characterized by growth of abnormal cells that can spread to other parts of the body.

Risk factors

Risk factors for solar keratosis include:

  • Age - the risk of solar keratosis increases with age;
  • UV radiation exposure - either short, intense exposure such as sunburn, or long-term accumulative exposure such as that gained from working outdoors;
  • Sun tanning or using tanning beds;
  • Having a family history of skin cancer;
  • Having fair skin, and;
  • Having a weakened immune system.

Signs and symptoms

Solar keratosis commonly appears on areas of the body exposed to sunlight, including the face, scalp, trunk of the body and back of the hands. Symptoms of solar keratosis include patches of skin appearing flat, scaly and yellow. Skin growths may also be pink, red, grey or skin color. They can develop to be hard, rough and wart-like.

Solar keratosis lesion.A solar keratosis lesion. 

Methods for diagnosis

Solar keratosis is mainly diagnosed upon its appearance. However, a skin biopsy may be performed if there is any doubt about the diagnosis, or concerns about cancerous change.

Skin biopsy

A biopsy is a tissue sample taken for microscopic examination in a laboratory. Local anesthetic may be used during biopsies. There are three types of skin biopsies:

  • Incisional biopsies, which involve the removal of the entire abnormal area of skin with a surgical knife (scalpel);
  • Punch biopsies, which involve the removal of a small circle of the whole skin layer, much like a hole-puncher removes holes in paper, and;
  • Shave biopsies, which involve shaving off the top layer of skin.

Skin punch biopsy.A skin punch biopsy. 

Local anesthetic

A type of medication that, when administered to an area, creates a localized loss of sensation by blocking nerve activity.

Cancerous

Pertaining to cancer, a disease characterized by growth of abnormal cells that can spread to other parts of the body.

Types of treatment

Conservative treatment

Solar keratosis lesions do not necessarily need to be treated. Some lesions can resolve if given time (usually within a year). Treatment may be recommended if lesions change in appearance or become tender. However, the importance of recognizing solar keratosis lesions, is the need for ongoing prevention. Wearing high sun protection factor (SPF) sunscreens, appropriate clothing to cover the body, and avoiding direct sunlight and tanning beds, can reduce the risk of developing further solar keratosis as well as other related skin cancers. 

Surgery

Lesions can be excised or scraped away, using a scalpel, curette, laser and/or electric current. The remaining wound can be closed with stitches and/or a wound dressing. 

Cryotherapy

Lesions can be cautiously frozen off with liquid nitrogen, by an experienced health professional. 

Medicated creams

Creams, gels (water-based) and ointments (more greasy) containing certain medications, which reduce inflammation or target abnormal cells, can be applied directly to the skin. These can contain medications such as diclofenac, fluorouracil, imiquimod and salicyclic acid.

Photodynamic therapy (PDT)

Photodynamic therapy involves the application of a cream that is absorbed by abnormal cells and then a special light is applied, which selectively damages the abnormal cells.

Potential complications

Treatment side effects

  • Skin ulceration - medicated creams have the potential to cause ulceration of the skin, particularly if used outside the recommended frequency or dosage;
  • Persistent white marks or scarring - medicated creams and surgery can result in changes to skin color and scarring.

Advanced solar keratosis

Left untreated, solar keratosis can develop into a type of skin cancer called squamous cell carcinoma.

Prognosis

In the majority of cases, solar keratosis responds well to treatment.

Prevention

The best way to prevent skin cancer is by minimizing your exposure to UV radiation, which can be done by avoiding sunlight during the times specific to your area, wearing protective clothing such as hats and long-sleeved shirts with collars and frequently applying sunscreen. Avoiding sun-tanning and tanning beds is also highly recommended.  

Practicing being sun smart and sun safe by wearing a hat and regular application of sunscreen.