Acne typically appears on the face, neck, chest, back, and shoulders because these are the areas with the most oil glands. Acne can come in the following forms:
- Comedones (blackheads and whiteheads). Comedones occur when hair follicles become clogged with oil, dead skin cells, and sometimes bacteria. Blackheads occur when the comedo enlarges and pops through the skin. The black color is due not to dirt but to a build-up of melanin. Whiteheads happened when the comedo stays below the surface of the skin; the white bubble seen is the trapped sebum and dead cells.
- Papules are small raised bumps that signal inflammation or infection in the hair follicles. Papules may be red and tender.
- Pustules are red, tender bumps with white pus at their tips.
- Nodules are large, solid, painful lumps beneath the surface of the skin. They're formed by the buildup of secretions deep within hair follicles.
- Cysts are painful, pus-filled lumps beneath the surface of the skin. These boil-like infections can cause scars.