Whitehead – is a plugged sebaceous gland with an opening that is not widely dilated. Whiteheads begin to bulge because the sebum produced cannot escape. They are generally soft,lack inflammation,and are easy to extract.
Backhead – is an open follicle with a black surface plug, which has been oxidized and discolored due to sebum’s contact with the air.
Papules – Is a small elevation of the skin, usually inflammatory, that does not contain pus. Papules are similar to vesicles in size, and if they progress they can become pustules.
Cyst- Is an abnormal membranous sac containing a gaseous, liquid or semi-solid substance.
Nodule- or Tumor is a solid mass within the skin. It may be soft or hard,fixed or freely moving.
Pustule – is a small inflamed elevation,the next step in the progression from a papule,filled with bacterial fluid and pus. Pustules appears red and cloudy or white.