Premalignant Skin Lesions
Premalignant lesions are growths that appear on the skin surface that can develop into a skin cancer. The lesions may look like rough, red or brown, scaly patches on the skin or brown to black patches that are raised and have a variety of different shades of brown within the lesion with an irregular shape. These patches occur in areas that have been exposed to the sun. They are often found on the face, hands, and arms and are more common in people with fair skin.
The most common premalignant skin lesion appears as a scaly or crusty growth (lesion) and is directly caused by overexposure to the damaging ultraviolet (UV) rays from the sun. This lesion is called, actinic keratosis (AK) which is also known as solar keratosis. These lesions typically appear on sun-exposed areas such as the face, the bald scalp, lips, and the back of the hands, and are often elevated, rough in texture, and resemble warts. Most AK’s become red, but some will be tan, pink, red, and/or flesh-toned. Untreated AKs can mutate into squamous cell carcinoma (SCC), the second most common form of skin cancer, and some experts believe they are actually the earliest stage of SCC.
Medicated creams and solutions are very effective by themselves or in combination with another form of treatment when a person has many actinic keratoses.
- 5-fluorouracil (5-FU) ointment or liquid (Effudex) is the most widely used topical treatment for actinic keratoses. It is effective against not only the surface lesions but also the ones that are not yet visible. This cream has a very high success rate and may cause reddening, swelling and crusting which are temporary. The lesions usually heal within two weeks of stopping treatment. There is rarely scarring and the cosmetic result is good.
- Imiquimod cream works by stimulating the immune system to produce interferon, a chemical that destroys cancerous and precancerous cells. The cream is generally well-tolerated, although it may cause redness and skin ulcerations in some cases.
- Diclofenac is a non-steroidal anti-inflammatory drug. The diclofenac prevents the inflammatory response associated with sun damage. It is used in individuals who are oversensitive to other topical treatments.
- Ingenol mebutate is the first topical therapy to effectively treat AKs in just two or three days. The most common side effects are skin redness, flaking/scaling, crusting and swelling.
When a more limited amount of lesions are present other modes of treatment may be available including:
Liquid nitrogen is a very cold fluid that has a temperature of around -330 Fahrenheit. When applied to actinic keratosis lesions, the freezing causes the AKs to shrink, crust and fall off. Temporary redness and swelling may occur after treatment, and in some patients, white spots (scars) may become permanent.
Chemical peel agents
Trichloroacetic acid (TCA) and/or similar chemicals are applied directly to the skin to cause a controlled and intentional superficial chemical burn of the AK tissue. The top layer is shed off and usually replaced within seven days. This technique requires local anesthesia and can cause temporary discoloration and irritation.
A carbon dioxide or erbium YAG laser is focused onto the lesion, and the beam cuts through tissue without causing bleeding. This is a good option for lesions in small or narrow areas, and, therefore, can be particularly effective for keratoses on the face and scalp, as well as actinic cheilitis on the lips. However, local anesthesia may be necessary, and some pigment loss can occur. Lasers are useful for people taking blood thinners or as a secondary treatment when others have not succeeded.
Certain chemicals can be applied to the skin surface that are photosensitive. That is, they break down with exposure to ultraviolet light rays and cause a chemical reaction. The reaction causes the death the AK cells with little damage to surrounding normal skin, although some swelling and redness often occur.
(atypical moles) are unusual benign moles that are similar to malignant melanoma. People who have them are at increased risk of developing single or multiple melanomas. The higher the number of these moles someone has, the higher the risk; those who have 10 or more have 12 times the risk of developing melanoma compared to the general population. Dysplastic nevi are found significantly more often in melanoma patients than in the general population.
At times it is difficult to distinguish between dysplastic nevi and early melanomas. (Sometimes, melanomas will begin within a dysplastic nevus.) To establish the difference, a doctor will remove the entire spot or a portion of it for examination in the pathology laboratory.