Definition of acne vulgaris
An inflammatory disease of the pilosebaceous unit, characterised by comedones, papules and pustules
Aims of treatment of acne?
- decreasing psychological morbidity
- preventing permanent scarring
Epidemiology of acne vulgaris?
- affects 85% between 12 and 24
- onset usually at puberty
- adolescence M>F
- 30% women and 1% men continue to have acne until 25y
- may persist into 40s (10% women)
- may develop in late 20s or 30s
What are some myths regarding aetiology of acne?
sounds silly but important if asked in osce
- affects only teenagers
- poor hygiene causes acne
- chocolate and fatty foods cause acne
- drinking lots of water improves acne
How does the normal pilosebaceous unit work?
sebaceous glands drain into hair follicle. Sebum is secreted into hair follicles and act as emollient for skin
What bacterium resides in the follicular duct?
Propionibacterium acnes
What is the pathogenesis causing acne?
- increase in sebum excretion rate (SER)
- abnormal follicular keratinisation and desquamation (hypercornification) leading to obstruction
- colonisation with P. acnes
- inflammation
What is seborrhoea?
Greasy skin
What causes seborrhoea?
end organ hypersensitivity/ decrease in sex hormone binding globule/ increase in androgens leads to an increase in the SER which leads to seborrhoea
What is a microcomedo?
a blocked pore
How does microcomedo occur?
Androgens/ FFA from sebum -> hyperkeratosis of follicle -> abnormal desquamation -> retention keratosis -> microcomedo
Which conditions do P. acnes bacteria thrive in?
sebum
How does inflammation occur in acne?
Products of P. acnes interact with host cells, causing inflammation
Types of non-inflammatory lesions?
Open and closed comedones
Build up of keratonous material
What are open comedones?
blackheads (black cos oxidation of melanin)
- dilated orifice
- layered with keratinous squamae
- P. acnes
What are closed comedones?
whiteheads
- undilated orifice
- disordered keratinous squamae
- P. acnes
Which out of open / closed comedones is more likely to become inflammed?
and why?
Closed as follicles can burst more easily
Superficial types of inflammatory lesions? How do they occur? Are they superficial or deep? How long do they take to heal? Do they scar?
- erythematous papules
- pustules
occur when a closed comodone bursts and releases fatty acids into the area
superficial
1-2 weeks
no
Deep types of inflammatory lesions?
- nodules
- cysts (rarely found in acne)
- abscesses (rare)
What are nodules?
How long do they take to heal?
Excessive inflammatory response in the surrounding dermis
Painful and take weeks-months to heal
scar
What is acne sequelae?
post inflammatory changes, transient, superficial inflammatory lesions do not scar
ice pick scar/atrophic scar/ hypertrophic/keloid scar from nodules/cyst/abscess
Factors aggravating acne
- occlusive cosmetics/hair products - oily
- heat/humidity
- excessive/ vigorous washing
- manipulation of lesions
- exogenous medications e.g. OCP/ steroids
DDx of acne vulgaris?
- rosacea
- peri-oral dermatitis
- folliculitis
Treatment of acne?
patient education and medication
