The assessment of acne: an evaluation of grading and lesion counting in the measurement of acne.

The basic morphology of acne--comedones, papules, pustules, and nodules--and the extent of involvement do not permit simple evaluation due to the number of variables involved. Because these acne lesions may vary in number during the natural course of the disease, various measurements have been developed, based on clinical examination and photographic documentation. These range from global assessments to lesion counting, with the latter providing more objective data.