Actinic keratosis

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Actinic keratosis
Classification and external resources
Actinic keratosis on the lip
ICD-10	L57.0
ICD-9	702.0
DiseasesDB	29438
MeSH	D055623

Actinic keratosis (also called solar keratosis, or AK) is a premalignant condition^[1] of thick, scaly, or crusty patches of skin.^[2]:719[3] It is more common in fair-skinned people. It is associated with those who are frequently exposed to the sun,^[4] as it is usually accompanied by solar damage. Since some of these pre-cancers progress to squamous cell carcinoma,^[3] they should be treated.

When skin is exposed to the sun constantly, thick, scaly, or crusty bumps appear. The scaly or crusty part of the bump is dry and rough. The growths start out as flat scaly areas, and later grow into a tough, wart-like area.

An actinic keratosis site commonly ranges between 2 and 6 millimeters in size, and can be dark or light, tan, pink, red, a combination of all these, or have the same pigment as the surrounding skin. It may appear on any sun-exposed area, such as the face, ears, neck, scalp, chest, backs of hands, forearms, or lips.

Prevention

Preventive measures recommended for AK are similar to those for skin cancer:

• Not staying in the sun for long periods of time without protection (e.g.:sunscreen, clothing, hats).
• Frequently applying powerful sunscreens with SPF ratings greater than 30 and that also block both UVA and UVB light.
• Wearing sun protective clothing such as hats, long-sleeved shirts, long skirts, or pants.
• Avoiding sun exposure during noon hours is very helpful because ultraviolet light is the most powerful at that time.

Diagnosis

Doctors can usually identify AK by doing a thorough examination. A biopsy may be necessary when the keratosis is large and/or thick, to make sure that the bump is a keratosis and not a skin cancer. Seborrheic keratoses are other bumps that appear in groups like the actinic keratosis but are not caused by sun exposure, and are not related to skin cancers. Seborrheic keratoses may be mistaken for an actinic keratosis.

Treatment

Various modalities are employed in the treatment of actinic keratosis:

• Diclofenac sodium 3% gel, e.g. Solaraze Gel, contains nonsteroidal anti-inflammatory drug. Recommended duration of therapy is 60 to 90 days.
• Cryosurgery, e.g. with liquid nitrogen, by "freezing off" the AKs
• 5-fluorouracil (a chemotherapy agent): a cream that contains this medication causes AKs to become red and inflamed before they fall off
• Photodynamic therapy:^[5] this new therapy involves injecting a chemical into the bloodstream, which makes AKs more sensitive to any form of light.
• Laser, notably CO₂ and Er:YAG lasers. A Laser resurfacing technique is often used with diffuse AKs.
• Electrocautery: burning off AKs with electricity
• Immune Response Modifier: topical treatment with imiquimod^[6] (Aldara), an immune enhancing agent
• Different forms of surgery
• Repcillin is a natural alternative using crocodile peptides

Regular follow-up after the treatment is advised by many doctors. The regular checks are to make sure no new bumps have developed and that old ones haven't become thicker.

Experimental treatments

In 2007, Australia biopharmaceutical company Clinuvel Pharmaceuticals Limited began clinical trials with a melanocyte-stimulating hormone called afamelanotide (formerly CUV1647)^[7] for mitigation of photodynamic therapy side effects in organ transplant patients.^[8][9]

Another Australian biopharmaceutical company, Peplin,^[10] is also developing a topical treatment for actinic keratosis. Formed in 1998 they are currently developing Ingenol Mebutate, which is the first in a new class of compounds and which is derived from Euphorbia peplus, or E. peplus, a rapidly growing, readily-available plant, commonly referred to as petty spurge or radium weed. The sap of E. peplus has a long history of traditional use for a variety of conditions, including the topical self-treatment of various skin disorders, such as skin cancer and pre-cancerous skin lesions. The company has recently redomiciled to the USA and is about to enter phase III trials with Ingenol Mebutate.

See also

• List of cutaneous conditions

External links

• American Academy of Dermatology
• American Osteopathic College of Dermatology
• National Library of Medicine and the National Institute of Health
• Actinic Keratosis photo library at Dermnet
• Medicinenet's article on Actinic Keratosis
• Information on Actinic Keratosis from The Skin Cancer Foundation

References