In March 1941 Eller and Wolff 1 suggested cryotherapy, or the use of carbon dioxide slush, in the treatment of recalcitrant cases of acne vulgaris and its scars. After this report, we began to use carbon dioxide slush in the treatment of severe and scarred lesions of acne vulgaris but found the method unwieldy and not particularly helpful in removing or improving the scars. It was observed, however, that cystic lesions would almost invariably disappear after a few treatments, and so we conceived the idea of using simply a pencil or block of solid carbon dioxide, or dry ice,® for the treatment of cystic acne. The results in the treatment of more than 2,000 patients with cystic or severe acne vulgaris have been so good that we have given up the surgical treatment of deep-seated acne lesions, which, we feel, increases scar formation.
The procedures we have used are as