Comedone formation: etiology, clinical presentation, and treatment.

An important feature in the etiology of acne is the presence of pilosebaceous ductal hypercornification, which can be seen histologically as microcomedones (Fig 1) and clinically as blackheads, whiteheads, and other forms of comedones, such as macrocomedones. There is a significant correlation between the severity of acne and the number and size of microcomedones (follicular casts), the presence of which is a measure of comedogenesis. This correlation can be demonstrated by skin surface biopsy using cyanoacrylate gel. In this procedure, microcomedones are sampled by applying cyanoacrylate gel to the skin surface. A glass microscopic slide is then applied on top of the gel and pressed firmly onto the skin for 1 minute(1-3). The glass slide is gently removed, taking with it the upper part of the stratum corneum and microcomedones, which are then analyzed by low-power microscopy or digital image analysis.(1-3)