Acne vulgaris.
Acne vulgaris is the formation of comedones, papules, nodules, pustules and/or cysts as a result of obstruction and inflammation of pilosebaceous units (hair follicles and their accompanying sebaceous gland). Acne develops on the face and the upper trunk.
It affects the sexes equally, starting usually between the ages of 12 and 14 years, tending to be earlier in females. The peak age for severity in females is 16–17 and in males 17–19 years. Acne vulgaris clears by the age of 23–25 years in 90% of patients, but some 5% of women and 1% of men still need treatment in their thirties or even forties.
Etiology:
- Excess sebum production
- Follicular plugging with sebum and keratinocytes
- Colonization of follicles by Propionibacterium acnes (a normal human anaerobe)
- Release of multiple inflammatory mediators
- Genetic – the condition is familial
Acne can be classified as:
- I. Non- inflammatory: Characterized by comedones. Comedones are sebaceous plugs impacted within follicles. They are termed open or closed depending on whether the follicle is dilated or closed at the skin surface. Plugs are easily extruded from open comedones but are more difficult to remove from closed comedones. Closed comedones are the precursor lesions to inflammatory acne.
- II. Inflammatory: Characterized by papules, pustules, nodules, and cysts. Papules and pustules occur when P. acnes colonizes the closed comedones, breaking down sebum into free fatty acids that irritate the follicular epithelium and eliciting an inflammatory response by neutrophils and then lymphocytes, which further disrupts the epithelium. The inflamed follicle ruptures into the dermis (sometimes precipitated by physical manipulation or harsh scrubbing), where the comedone contents elicit a further local inflammatory reaction, producing papules. If the inflammation is intense, grossly purulent pustules occur.
Nodules and cysts are other manifestations of inflammatory acne. Nodules are deeper lesions that may involve > 1 follicle, and cysts are large fluctuant nodules.
Clinical presentation of acne:
- A) Superficial lesions
- Open and closed comedones (blackheads and whiteheads)
- Papules (small, tender red bumps)
- Pustules (white or yellow "squeezable" spots)
- B) Deeper lesions
- Nodules (large painful red lumps)
- Pseudocysts (cyst-like fluctuant swellings)
- C) Secondary lesions
- Excoriations (picked or scratched spots)
- Erythematous macules (red marks from recently healed spots, best seen in in fair skin)
- Pigmented macules (dark marks from old spots, mostly affecting those with dark skin)
- Scars or various types
Acne can also be classified into:
- I. Mild acne
- <20 comedones
- <15 inflammatory lesions
- Or, total lesion count <30