DermatologyTier 1Disease (DEADMAN)

Acne

Description

Chronic inflammatory disease of the pilosebaceous unit - comedones (open/closed), papules, pustules, nodules/cysts in severe disease
Graded mild / moderate / severe by lesion count, inflammation, and scarring risk - drives treatment intensity
Distinguish from acne as a sign of systemic disease (sudden severe onset, virilisation, drug-induced) - see cutaneous manifestations of systemic diseases for that angle

Affects ~85% of adolescents to some degree - the commonest skin disease of that age group
Adult persistent/late-onset acne - more common in women, often jawline/lower face distribution, frequently hormonally driven
Significant psychosocial burden independent of physical severity, especially in adolescents

Four interacting mechanisms:
- Follicular hyperkeratinisation -> comedone formation
- Increased sebum production (androgen-driven)
- *Cutibacterium acnes* proliferation within the follicle
- Inflammation - innate immune response to C. acnes and follicular rupture
Androgens drive sebocyte activity - explains flares around menses, PCOS association, and response to anti-androgen therapy
Comedogenic cosmetics/occlusion, mechanical friction, and some medications can trigger/worsen (see systemic-manifestations note for drug-induced acne)

Clinical - diagnosis and severity grading both clinical

Comedonal - open (blackheads)/closed (whiteheads) comedones, minimal inflammation
Papulopustular - inflammatory papules/pustules superimposed on comedones
Nodulocystic/severe - deep painful nodules, high scarring risk, may need escalation straight to isotretinoin
No routine investigations needed for typical adolescent acne

When to investigate for a cause

Sudden severe onset, resistance to standard therapy, or signs of hyperandrogenism (irregular menses, hirsutism) in a woman - screen as per the systemic-manifestations note

A. Mild - topical monotherapy or combination

Topical retinoid (adapalene, tretinoin, or newer agents tazarotene lotion, trifarotene) - foundational, addresses comedones and has anti-inflammatory effect
Benzoyl peroxide - antimicrobial, no resistance risk (unlike antibiotics), often combined with retinoid or topical antibiotic in a single product
Topical antibiotic (clindamycin) - always combined with benzoyl peroxide, never as monotherapy (resistance)
Newer topical options: clascoterone (topical anti-androgen), topical dapsone, minocycline foam

B. Moderate - add oral therapy

Oral doxycycline/minocycline (anti-inflammatory, not purely antimicrobial mechanism) - combined with topical retinoid + benzoyl peroxide, course typically 3-4 months, limit systemic antibiotic duration and always combine with a topical (reduces resistance)
Combined oral contraceptive pill or spironolactone - effective adjunct for hormonally-driven female acne, especially with a perimenstrual/jawline pattern

C. Severe, scarring, or psychosocially significant, or failed standard therapy

Oral isotretinoin - strongly recommended for severe/scarring/treatment-resistant acne
- Monitoring: LFTs, fasting lipids, pregnancy test (for those with pregnancy potential) - routine FBE monitoring not required per updated guidance
- Mandatory pregnancy prevention program for anyone with pregnancy potential - strict teratogen
- Counsel on mood changes (monitor for depression, though causal link debated), dryness, photosensitivity, transient flare on initiation

D. Adjunct/procedural

Intralesional corticosteroid injection for individual large inflamed nodules/cysts - rapid symptom relief, reduces scarring risk
Combining topicals with different mechanisms and limiting monotherapy systemic antibiotic use are both explicit good-practice recommendations

PCOS/hyperandrogenism in women with adult-onset or refractory jawline acne
Significant psychological impact - depression, anxiety, social withdrawal, disproportionate to objective severity, especially in adolescents
Post-inflammatory hyperpigmentation - more prominent and prolonged in darker skin types
Acne scarring (icepick, boxcar, rolling) - permanent without dermatological intervention

Most adolescent acne improves/resolves by the early-mid 20s; a significant minority (particularly women) have persistent adult acne
Delayed/inadequate treatment of nodulocystic acne - permanent scarring, the main reason for early escalation to isotretinoin rather than prolonged trials of milder therapy in severe disease
Isotretinoin achieves durable remission in the majority; some require a second course
Untreated psychological impact can outlast the skin disease itself - screen for mental health impact at diagnosis, not only with severe disease

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