Acne: clinical presentations.

Acne vulgaris, the most common disease of the skin, can be manifested in a wide variety of clinical presentations. As a result of this clinical variation, there are almost as many classifications of acne as there are clinicians with particular interest in the disease. Thus acne has been classified as types I-IV, inflammatory versus noninflammatory, comedonal, comedopapular, papular, papulopustular, pustular, and "cystic" or nodular (even nodular-cystic). For those who are enamored of classification, there are subdivisions of the various categories, including "sandpaper comedones" and microcysts. There is even disagreement as to what constitutes a papule versus a nodule. The classic textbook definition of a nodule refers to lesions 1 cm or larger, but the early investigators of oral isotretinoin defined nodules as 4 mm or larger, and this definition has creeped into many texts, recently clarified by Bologna.(1)