Актинічний кератоз

Actinic keratoses often have adherent scales and are sometimes more easily felt than seen. Actinic keratoses can appear thickened or hypertrophic and sometimes form a cutaneous horn. They may be pink, red, or, less commonly, gray or brown. Lesions frequently develop in sun-exposed areas (eg, balding scalp, face, lateral neck, distal upper or lower extremities). Diffuse involvement of the lip is called actinic cheilitis.

• Clinical examination

Diagnosis of actinic keratoses is often based on visual and tactile examination; lesions feel rough and scaly on palpation. They should be differentiated from seborrheic keratoses, which increase in number and size with age. Seborrheic keratoses tend to appear waxy and stuck-on but can take on an appearance similar to that of actinic keratoses. Close inspection usually reveals distinguishing characteristics of the lesion. An actinic keratosis can also be distinguished from a seborrheic keratosis by the rough, gritty feel of the scale and the erythema. Unlike actinic keratoses, seborrheic keratoses also occur on non–sun-exposed areas of the body and are not precancerous.

Актинічний кератоз (волосиста частина шкіри голови)

Зображення

DR P. MARAZZI/SCIENCE PHOTO LIBRARY

• Lesion-directed or field-directed therapy

Treatment options depend on the number of lesions, their location, extent of photodamage, and patient preference, but typically they are divided into 2 categories:

• Lesion-directed therapy

• Field-directed therapy

In lesion-directed therapy, individual lesions are physically removed. This option may be better if the patient has only a few actinic keratoses, or if the patient is unable or unwilling to undergo other therapy options. Cryosurgery (freezing with liquid nitrogen) is the most common lesion-directed therapy. Curettage (scraping with a curette) is an alternative. Lesion-directed therapies have the benefit of being single, in-office procedures, but they may not address subclinical changes and have a higher risk of scarring.

In field-directed therapy, topical treatments are applied to larger, diffuse areas of involvement. Topical fluorouracil (5-FU) cream and imiquimod cream are the usual first-line drug treatments. Alternatives include diclofenac gel and tirbanibulin ointment.

• 5-FU inhibits thymidylate synthetase, limiting DNA synthesis and causing death of damaged cells. 5-FU 5% cream is applied 2 times a day for 3 to 4 weeks. A recent study has shown 5-FU to be the most effective treatment for actinic keratoses (1). Early data suggest that combining 5% FU cream with 0.005% calcipotriol may enhance efficacy of 5-FU (2).

• Imiquimod is an immune response modifier that stimulates local cytokine induction, resulting in a brisk local inflammatory reaction. Imiquimod 5% cream is applied 2 times a week for 16 consecutive weeks.

• Diclofenac is a nonsteroidal anti-inflammatory drug that inhibits both cyclooxygenase and upregulation of the arachidonic acid cascade. Diclofenac 3% (in a 2.5% hyaluronan gel) is applied 2 times a day for 60 to 90 days. Its use is limited by its low efficacy.

• Tirbanibulin is a microtubule inhibitor that inhibits tubulin polymerization and Src kinase signaling, inducing death of damaged cells. Tirbanibulin 1% ointment is applied once a day for 5 days; however, there are currently only short-term data on safety and efficacy available.

These topical drugs can cause inflammation (often with redness and scaling) and pain during treatment and usually for 1 to 2 weeks afterward.

Photodynamic therapy is another type of field-directed therapy. It involves topical application of a photosensitizer (eg, aminolevulinate, methyl aminolevulinate) followed by light of a specific wavelength that preferentially affects photodamaged skin. Like topical field-directed therapy, photodynamic therapy can cause redness and scaling during treatment. More than one treatment session may be needed.

If patients do not respond to therapy, clinicians should consider doing a biopsy to rule out squamous cell carcinoma.

Patients should also be told about the importance of sun-protective measures.