Acne aestivalis.

This is the first American report, to our knowledge, of a case of acne aestivalis, which occurred in a woman with a recurrent acneform eruption in summertime. The histopathologic sequence was very similar to that found in cases of steroid acne; namely, local necrosis of the follicular epithelium was followed by the formation of a comedo. No cause was found. Treatment with tretinoin brought about regression of the lesions.