Clinical aspects of acne.

Acne vulgaris may present in a wide variety of clinical forms depending on the type, number and severity of the predominant lesion. Thus there may be mild, moderate or severe comedonal or inflammatory acne, the latter with many subtypes. Furthermore, the number and extent of the lesions do not necessarily predict the response to therapy, and patients may also be categorized as therapeutically responsive or therapeutically refractory. Finally, there may be alterations in the clinical manifestations and therapeutic response depending on the distribution of the lesions, age of the patient and provoking or complicating factors.