Skin Disorders Guide

Topically applied cytotoxic agents can be effective in the treatment of some premalignant and malignant skin diseases. Actinic keratoses on the face and scalp respond rather well to topically applied fluorouracil (Efudex and Fluoroplex). Applications of fluorouracil in a 1 % to 5% concentration are carried out on a twice daily basis. After several days of application, areas of dysplastic skin become inflamed, some­times rather painfully so. At that point the frequency of application can be reduced to once daily for a total treatment period of 3 to 4 weeks. In the weeks following cessation of therapy the inflammation gradually resolves and the keratoses disappear. Occasionally during this period, basal or squamous cell carcinomas that were previously hidden by numerous keratoses become apparent. These tumors, once identified, will require additional surgical or electrosurgical therapy. The results obtained are cosmetically excellent but are not permanent; retreatment may be necessary in 2 to 3 years. A new topical agent, masoprocol (Actinex), has recently been released for treatment of actinic keratoses. It is not yet clear how it will compare in efficacy with fluorouracil, but it does seem to cause less troublesome inflammation during use.

Topically applied nitrogen mustard (mechlorethamine) is used In the treatment of mycosis fungoides. A 10-mg ampule of nitrogen mustard (Mustargen) is mixed with 50 to 100 cc of tap water, and this diluted working solution is applied to the entire surface of the skin (with the face, scalp, and skin folds excepted) daily or 3 times/week. Applications are continued until the lesions resolve, at which time tile frequency of application can be reduced to once weekly. Usually, this maintenance program must be continued indefinitely, or the disease will reappear. Allergic sensitization to nitrogen mustard occurs with some frequency and may require cessation of treatment. Keratoses and squamous cell carcinomas may occur as a result of long-term therapy. The mechanism by which nitrogen mustard treatment is effective is unknown but is more likely due to the modulation of immunologic factors rather than a direct cytotoxic effect.

Podophyllin is a cytotoxic agent used in the treatment of genital, nonkeratinizing warts. Historically, a 25% concentration in tincture of benzoin has been applied on a biweekly basis in the physician’s office. Patients were instructed to wash the product off in 2 to 8 hours. Irritation as a result of these applications was highly variable and was sometimes extremely painful. Recently, a standardized product with known amounts of active podophyllin (Condylox) has become commercially available. This preparation can be used at horne by the patient. It is applied twice daily for 3 consecutive days followed by a rest period of 4 days. The cycle is repeated for a maximum of 4 weeks. Irritation is tolerable, and cure rates in the 40% to 60% range have been reported.