Actinic keratosis/ actinic keratoses

Pre-cancers of the skin

Diagram of Skin Layers.

What are actinic keratoses (AKs) of the skin?

Actinic keratoses (plural of actinic keratosis) are growths of the skin that are caused by cumulative ultraviolet (UV) light exposure.  These growths arise from a type of skin cell called the keratinocyte.  Because actinic keratoses are caused by ultraviolet light exposure, they most frequently arise in areas of sun-exposed skin.  When this type of growth occurs on the lips, it is called actinic cheilitis.

  Actinic keratoses are pre-cancers.  A fraction of these growths turn into squamous cell carcinomas of the skin if left untreated.

How do actinic keratoses present?

Actinic keratoses can present in many different ways.  They are often skin-colored, pink, red, tan or brown.  They are often gritty in texture, reflecting heaped-up dead skin cells.  They are most often located in the sun-exposed areas such as the face, ears, scalp, upper chest, forearms, and back of the hands.

How can actinic keratoses be prevented?

Because actinic keratoses are caused by ultraviolet radiation exposure, good sunscreen and sun protection measures can help prevent these growths.  However, keep in mind that these growths are caused by cumulative ultraviolet radiation exposure so good daily sunscreen and sun protection will give you the maximal benefit in prevention.

How are actinic keratoses diagnosed?

Actinic keratoses are most commonly diagnosed by dermatologists (skin doctors).

  Most actinic keratoses can be diagnosed based on their appearance alone.  However, actinic keratoses can sometimes mimic other growths including squamous cell carcinomas of the skin and seborrheic keratoses.  Because treatment for these various growths is different, a sample of skin called a biopsy may be taken to definitively distinguish between these growths.

How are actinic keratoses treated?

Actinic keratoses may be treated in several different ways.  When these growths are discrete, cryotherapy is commonly used.  When there are many thin actinic keratoses clustered together, creams, photodynamic therapy or peels may be used to treat the entire “field” of actinic keratoses.  Think of these as a treatment that gets rid of weeds when they are still on the ground.  When the actinic keratosis is very scaly (called a hypertrophic actinic keratosis), electrodesiccation and curettage may be pursued.

Below is a summary of some of the treatments that may be used to treat actinic keratoses:

  • Cryotherapy – This is cold therapy. Typically, a liquid nitrogen spray is used to freeze the actinic keratosis.  After the treatment, the spot is red.  It may even blister and crust over after the treatment.
  • Creams or Gels – Commonly prescribed topical treatments include 5-fluorouracil (e.g. Efudex ® or Carac ®) or imiquimod (e.g. Aldara ®).  5- fluorouracil is a chemotherapeutic medication while imiquimod induces an enhanced immune response towards the actinic keratosis.  A newer topical agent is ingenol mebutate gel which does not need to be applied for as long as the 5-fluorouracil or imiquimod.  These creams or gels are often prescribed when there are many clustered actinic keratoses. Other creams and gels that may be prescribed include topical retinoids and diclofenac sodium.  These latter topical therapies are not as effective and are less commonly prescribed as the primary treatment for actinic keratoses.
    • Photodynamic therapy (PDT) – Photodynamic therapy involves the application of a photosensitizing agent such as an aminolevulinic acid (e.g. Levulan Kerastick ®) which sits and soaks into the top layer of the skin.  The skin is then exposed to a light which activates the photosensitizing agent.  Redness and irritation are expected after the treatment.  Photodynamic therapy is often used to treat a “field” of actinic keratoses as well.
    • Chemical peels – Chemical peels involve the application of a liquid such as trichloroacetic acid (TCA) to the area with the actinic keratoses.  Because it can be applied over an area with multiple actinic keratoses, this treatment may be used as “field” therapy as well.
      • Laser Surgery – A carbon dioxide or erbium YAG laser may be used to obliterate the actinic keratosis.  This is a less commonly used treatment.

      When should I be concerned or contact my physician?

      If your actinic keratosis persists after treatment, let your physician know.  Sometimes the actinic keratosis will require multiple treatments.  Additionally, if the growth does not resolve, it may require further investigation into whether it is a skin cancer such as squamous cell carcinoma.  If you develop excess redness, irritation, burning, swelling or other concerning symptoms after your treatment, also contact your physician.

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