Actinic keratosis
Synonyms and keywords: Solar keratosis; AK

# Overview
Actinic keratosis is a premalignant condition of thick, scaly, or crusty patches of skin. It is  most common in fair-skinned people who are frequently exposed to the sun, because their pigment isn't very protective. It usually is accompanied by solar damage. Since some of these pre-cancers progress to squamous cell carcinoma, they should be treated.

# Pathophysiology
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.

# Diagnosis

## Physical Examination
An actinic keratosis site commonly ranges in between 2 to 6 millimeters, and can be dark or light, tan, pink, red, a combination of all these, or the same pigment of one's skin. It may appear on any sun-exposed area, such as the face, ears, neck, scalp, chest, back of hands, forearms, lips etc.

### Skin
- Keratosis solar. Adapted from Dermatology Atlas.
- Keratosis solar. Adapted from Dermatology Atlas.
- Keratosis solar. Adapted from Dermatology Atlas.
- Keratosis solar. Adapted from Dermatology Atlas.
- Keratosis solar. Adapted from Dermatology Atlas.
- Keratosis solar. Adapted from Dermatology Atlas.
- Keratosis solar. Adapted from Dermatology Atlas.
- Keratosis solar. Adapted from Dermatology Atlas.
- Keratosis solar. Adapted from Dermatology Atlas.
- Keratosis solar. Adapted from Dermatology Atlas.
- Keratosis solar. Adapted from Dermatology Atlas.
- Keratosis solar. Adapted from Dermatology Atlas.
- Keratosis solar. Adapted from Dermatology Atlas.
- Keratosis solar. Adapted from Dermatology Atlas.
- Keratosis solar. Adapted from Dermatology Atlas.
- Keratosis solar. Adapted from Dermatology Atlas.
- Keratosis solar. Adapted from Dermatology Atlas.
- Keratosis solar. Adapted from Dermatology Atlas.
- Keratosis solar. Adapted from Dermatology Atlas.
- Keratosis solar. Adapted from Dermatology Atlas.
- Keratosis solar. Adapted from Dermatology Atlas.
- Keratosis solar. Adapted from Dermatology Atlas.
- Keratosis solar. Adapted from Dermatology Atlas.

## Other Diagnostic Studies
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
Regular follow-up after treatment is advised by many doctors. The regular checks are to make sure new bumps have not developed and that old ones haven't become thicker and/or have skin disease.

## Primary Prevention
Preventative 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 15 and that also block both UVA andUVB light.
- Using sunscreen even in winter sun exposure.
- 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.

# Future or Investigational Therapies
As of 2008 a company in Australia named Clinuvel Pharmaceuticals Limited is performing clinical trials with a melanocyte-stimulating hormone named melanotan (which they refer to as CUV1647) for actinic keratosis in organ transplant patients.