This is a common manifestation of excessive sun exposure in people of Celtic background and fair akin. It is extremely common in Australia, particularly on the backs of the hand and on the face; It is a precancerous, or premalignant, change in the epidermis. However progression to malignancy occurs in only a minority of these keratoses.
Features. Solar keratoses appears as small, rough patches on the skin surface. Usually they are skin coloured or red, and sting on exposure to sunlight. The scales may fall or be knocked off, but will invariably recur. Occasionally they spontaneously bleed. Some are very small, whereas others can be quite large and grow horny protuberances. Thickening of the base of the lesion, with increasing redness and tenderness, indicates activity and the possibility of malignant change.
Treatment.
1. Cryotherapy
This is the most popular treatment, using either solid carbon dioxide or liquid nitrogen.
2. Diathermy or curettage
When lesions are thick or if malignant change is suspected, this is the preferred treatment, the advantage being that microscopic examination can be performed on the suspect tissue.
3. Chemotherapy
More recently a cytotoxic chemical, 5 Fluououracil (5 F.U.) has been used in the destruction of solar keratoses. It is applied in the form of ointment or lotion twice dotty for 3-4 weeks. Where keratoses or other solar damage is present, acute inflammation followed by superficial erosion will occur. One or two weeks later, healing without scarring and without the return of the keratoses occurs. Frequently, patients observe that the cure is worse than the disease. As this form of treatment is not adequate for basal cell carcinomas, which could be mistaken for solar keratoses, careful diagnosis before treatment and follow-up afterwards is mandatory.
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