By Rajnish Mago, MD (bio)
What is acne?
When we say “acne,” we typically mean “acne vulgaris” and that is the sense in which I will use the word “acne” on this page. There is also another disease called “acne rosacea.”
What happens in acne?
1. Excessive amounts of dead skin cells (keratinocytes) block the hair follicle (“pilosebaceous duct”).
2. Androgens lead to increased production of sebum (an oily secretion).
3. A particular type of bacteria (Propionibacterium acnes) grow in this blocked hair follicle.
4. The whole thing gets inflamed.
Different types of lesions in acne
In speaking to patients, it can be helpful to know the difference between these different types of acne lesions (source: Mayo Clinic website).
“Whiteheads” are lesions in which the hair follicle (“pore”) is blocked.
“Blackheads” are lesions in which the hair follicle (“pore”) is open.
“Papules” are small red and tender bumps in the skin.
“Pimples” are papules (see above) with pus at their tips.
“Nodules” are large, solid, and painful lumps that are felt below the surface of the skin.
“Cystic lesions” are painful, pus-filled cysts below (nodules) Painful, pus-filled lumps that are felt below the surface of the skin.
Dawson AL, Dellavalle RP. Acne vulgaris. BMJ. 2013 May 8;346:f2634. doi: 10.1136/bmj.f2634. Review. PubMed PMID: 23657180.
Mayo Clinic. Acne: Symptoms and Causes
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