The scattered lesions caused by acne can manifest as single or multiple bumps generally called nodules or papules. The lesions are associated primarily with the sebum-producing glands that surround hair follicles in skin that is visibly greasy. Lesions are typically distributed to the face, neck, chest, shoulders, back and upper arms. Both blackheads and whiteheads disrupt the flow of sebum. Whiteheads are keratin plugs, which close the gland opening.
Blackheads are also keratin plugs in the gland opening but the gland remains open to the outside.
Whiteheads and blackheads may also be present in people who suffer from acne. Acne is most likely caused by a combination of factors. First, there is an increase in sebum production and a blockage of the hair follicle. With the follicle blocked, the population of normal bacteria in the follicle increases dramatically. Acne is common in adolescents and young adults.