Types of Acne lesions
Comedones– These are noninflammatory lesions called whiteheads and blackheads. They develop when the hair follicle is blocked by a keratin plug trapping the sebum underneath. As the trapped sebum increases, it creates pressure which ends up becoming a comedone. There are 2 types:
Closed comedone– a whitehead, a noninflamed lesion with a white center that stays below the surface of the skin
Open comedone– Blackhead, noninflammatory lesion with a dark centre. It develops when the comedone pops out through the surface of the skin, exposing the melanin ( dark pigment in the skin) to oxygen in the air.
Papules– inflammatory lesions that are small firm and red commonly referred to as pimples.
Pustules– a papule that contains pus, whitish substance which contains a lot of white blood cells. It usually is a red pimple with a white center.
Cyst / Nodule– Tender pus filled papule or pustule that is deeper in the skin. They occur when the immune system tries to contain the invader (bacteria) and the epidermis wraps around the hair follicle. When the pus hardens inside, the lesion becomes a nodule.