These bacteria produce chemicals and enzymes that can cause inflammation. When the plugged follicle can no longer hold its contents, it bursts and spills everything onto the nearby skin sebum, shed skin cells, and bacteria. Lesions or pimples develop as a result of the skin s being irritated. 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. Nodules large, painful, solid lesions that are lodged deep within the skin. Cysts deep, inflamed, pus-filled lesions that can cause pain and scarring.