Skin Disorders Guide

Chemical cauterants such as bichloroacetic and trichloroacetic acid are very useful for the destruction of benign, superficial lesions. In most situations, trichloroacetic acid in a concentration of 35% to 50% is used. A saturated solution (approximately 80%) can be used if the operator is experienced and very careful.The advantages of chemical cauterants are two fold, first, no injected anesthesia is required, and second, bleeding does not occur. In using trichloroacetic acid, the solution is applied with the wooden end of a cotton-tipped applicator or with a miniature cotton swab such as the urethral Calgiswab. A larger swab carries too much acid and increases the risk of running and scarring. Even with the smaller applicators, the end should be brushed against the neck of the bottle to be sure that there is no loose drop that could accidentally fall from the tip. The lesion is then barely moistened with the solution, none of the solution is allowed to touch the surrounding normal skin.

Generally, there is no discomfort for the first 60 to 90 seconds after application. The operator can thus treat several lesions before the patient is aware of the process. This is a property that is clearly advantageous when small children with multiple lesions must be treated. Pain after application reaches a maximum in about 5 to 15 minutes and thereafter subsides fairly quickly. Most patients find the overall degree of discomfort quite tolerable.

Within several days of treatment, necrotic tissue forms at the site of application. This dead tissue sloughs spontaneously, and complete healing takes place in approximately 10 days. The cosmetic appearance at the treated area is generally excellent, but occasionally, pigment loss or a small amount of scarring is visible. The destruction caused by spillage of even a drop or two of these fluids is very great, and I cannot overemphasize the care that must be taken during their use.

These solutions are best used on nonscaling, benign lesions such as genital warts, molluscum contagiosum, skin tags, and some warts. Seborrheic keratoses can be treated if they are not too keratotic. Most hand and foot warts must be trimmed to reduce the amount of overlying keratin before chemical cauterants are used. Cauterants are not used for malignant lesions because the destruction is insufficiently deep to ensure cure.