 The initial change is a disorder of follicular epithelial differentiation, during which the cornea cells keratinocytes which are the follicle polissebáceo are excessively released in the lumen. The result of this event is the appearance of the precursor, microcomedão, from which the lesions of acne are developed closed comedones, open comedones, papules, pustules and nodules. The dilation of the follicular infundibulum with the material produces a corneal comedão closed. This is the first clinically visible lesions of acne. As hyperkeratosis extends to the upper infundibulum, extended its opening, it formed the comedão open. 