INTRODUCTION Also known as solar or senile keratoses, these neoplasms are a common form of premalignant skin lesion seen on the face. Actinic keratoses are related to ultraviolet radiation damage of epidermal cells on sun-exposed areas of the face, hands, scalp, and eyelids. They occur more commonly in fair-skinned middle-aged or older individuals. The risk of malignant transformation is low, about 0.25% per year, but the ultimate development of squamous cell carcinoma in untreated lesions is as high as 20%. Up to 60% of squamous cell carcinomas are said to begin as actinic keratosis. Although some individual actinic keratoses will spontaneously resolve when sun-exposure is reduced, new lesions tend to develop. Squamous cell carcinomas arising from actinic keratoses are believed to be less aggressive than those developing de novo. Actinic keratosis may lie on a continuum toward squamous carcinoma, and recent chromosome aberration and gene mutation studies indicate an association between these two lesions. It has been suggested that actinic keratosis be referred to as "incipient intraepidermal squamous cell carcinoma."
CLINICAL PRESENTATION Actinic keratoses usually appear as multiple, round, flat-topped erythematous papules with an adherent superficial white scale. Early lesions may be felt as gritty rough spots before they can be seen. On occasion they may develop hyperkeratosis and present as a cutaneous horn. Actinic keratosis can be pigmented which can confuse the diagnosis.
HISTOPATHOLOGY The epidermis usually is slightly thickened with orthokeratosis, parakeratosis, hyper-granulosis, and cytologically atypical cells resulting in a variable loss of the normal orderly stratified arrangement of the epidermis. The atypical keratinocytes may form small buds or broad or elongated rete ridges. The dermis has actinic elastosis and may have a mild chronic inflammatory infiltrate. The hypertrophic (hyperplastic) form of actinic keratosis has prominent orthokeratosis and parakeratosis, which may result in formation of a cutaneous horn. The hyperplastic epidermis may exhibit conspicuous papillomatosis. Another example of actinic keratosis is shown in the terminology chapter under "parakeratosis."
DIFFERENTIAL DIAGNOSIS The differential diagnosis includes seborrheic keratosis, inverted follicular keratosis, basal cell carcinoma, and squamous cell carcinoma. When pigmented they can be confused with pigmented basal cell carcinoma, lentigo, or malignant melanoma.
TREATMENT Simple surgical excision or less invasive destruction is recommended in most cases. Multiple lesions respond to topical 0.5% fluorouracil cream applied twice daily for two to three weeks, but this is associated with local skin irritation. Cryotherapy is associated with a 97% initial response rate, with a three year recurrence of 11%. Photodynamic therapy involving a combination of photosensitizing agents with intense pulsed light shows promise in the treatment of multiple or recurrent lesions. More recently topical 5% imiquimod cream has been shown to be effective in treating actinic keratosis. The mechanism of action may be related to its ability to stimulate a cutaneous immune response.
Was this article helpful?
Do You Suffer From ASTHMA Chronic asthma is a paralyzing, suffocating and socially isolating condition that can cause anxiety that can trigger even more attacks. Before you know it you are caught in a vicious cycle Put an end to the dependence on inhalers, buying expensive prescription drugs and avoidance of allergenic situations and animals. Get control of your life again and Deal With Asthma Naturally