People with acne frequently have a variety of lesions, some of which are shown in figures 2, 3, and 4 (graphic omitted.) The basic acne lesion, called the comedo (kom´-e-do) or comedone, is simply an enlarged hair follicle plugged with oil and bacteria. This lesion is often referred to as a microcomedo because it cannot be seen by the naked eye. If the plugged follicle, or comedo, stays beneath the skin, it is called a closed comedo or whitehead. Whiteheads usually appear on the skin surface as small, whitish bumps. A comedo that reaches the surface of the skin and opens up is called a blackhead because it looks black on the skin’s surface. This black discoloration is not due to dirt. Both whiteheads and blackheads may stay in the skin for a long time.