Specific History

Onset

This type of keratosis is seen with increased incidence in patients from the fifth decade of life onward. The individual lesions begin insidiously as erythematous patches of vasodilation that are often more apparent after solar exposure. Early lesions are usually otherwise asymptomatic.

Evolution of Disease Process

AKs develop after a long latency period (one to two decades), and are caused primarily by solar radiation in the UVB or sunburn range from 2900 to 3200 A. They occur in groupings and are limited to sun-exposed skin. The early erythematous lesions can progress to forms that (1) scale (keratotic type), (2) thicken dramatically (cutaneous horn type), (3) develop a brown branny scale (pigmented type), or (4) become violaceous, slightly indurated, and inflamed to resemble papules of lichen planus (lichenoid type). The last type is uncommon and probably represents an AK with an immune response aimed at rejection. These more developed forms are often mildly symptomatic and patients will complain of intermittent itching and prickling, especially after solar exposure. Following a lengthy latent period some AKs evolve into squamous cell carcinomas, usually of low metastatic potential. Patients will occasionally report spontaneous clearing of specific lesions, possibly a consequence of the histologic changes seen in the lichenoid type.

Thickening at the base of an AK, the presence of a cutaneous horn, or failure to respond promptly to proper cryotherapy should suggest the possibility of malignancy.

Evolution of Skin Lesions

See Evolution of Disease Process section, above.

Provoking Factors

Extensive sun exposure obtained during recreation or in outdoor occupations is the major cause. Climates with predominantly warm sunny days, increased proximity to the equator, and exposure at higher altitudes all increase the injury, which is of a cumulative nature. These lesions occur primarily in persons of Celtic heritage with types I and II complexions, who sunburn easily.

Self-Medication

Inappropriate self-treatment with topical 5-fluorouracil (5-Fu) obtained from relatives or prescribed by misguided practitioners can alter lesions or hide established malignancies without effectively removing them. Patients will also attempt to treat themselves with various cosmetics and patent medications, but soon discover that this is fruitless.

Supplemental Review From General History

A history of lifetime sun exposure, ease of burning, and regular use of sunscreens and protective clothing should be reviewed.

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