Acne vulgaris is a common chronic disorder of the pilosebaceous unit characterized by comedones, inflammatory papules/pustules, and nodules that can lead to scarring and dyspigmentation. Pathogenesis involves follicular hyperkeratinization, excess sebum production (androgen-mediated), Cutibacterium acnes dysbiosis and inflammation, and neuroendocrine/immune factors. Treatment is severity- and phenotype-based, prioritizing topical retinoids plus benzoyl peroxide, judicious antibiotics, hormonal therapies in appropriate patients, and isotretinoin for severe or refractory disease. Scar prevention and management of postinflammatory hyperpigmentation (PIH) are central to long-term outcomes.
Epidemiology
- Affects up to 85% of adolescents; persists into adulthood in many, especially women.
- Risk factors: family history, androgen excess, occlusive cosmetics/helmets, certain medications (steroids, lithium, EGFR inhibitors).
Pathophysiology
- Microcomedone formation via abnormal follicular keratinization.
- Androgen-driven sebaceous activity.
- C. acnes strains and biofilms with activation of innate/adaptive immunity (TLR, IL-1, IL-17).
- Neuroinflammation and stress may exacerbate.
Clinical Features and Classification
- Lesion types: open/closed comedones, inflammatory papules/pustules, nodules/cysts; truncal involvement common.
- Severity: mild (comedonal ± few inflammatory), moderate (widespread papulopustular), severe (nodulocystic/conglobata).
- Sequelae: atrophic/boxcar/icepick/rolling scars, hypertrophic/keloids; PIH and PIE (erythema) especially in skin of color.
Differential Diagnosis
- Rosacea, folliculitis (including Malassezia), periorificial dermatitis, gram-negative folliculitis, steroid acne, hidradenitis (in folds), SAPHO.
Management
- Foundational
- Gentle, non-comedogenic skin care; avoid over-washing and harsh scrubs.
- Sun protection; manage mechanical occlusion (helmets, masks).
- Address psychosocial impact; set expectations (6–8 weeks to see change).
- Topical therapies
- Retinoids: adapalene, tretinoin, tazarotene—core for comedonal and maintenance; start low frequency to mitigate irritation; microencapsulated/cream vehicles for sensitive skin.
- Benzoyl peroxide (BPO): antibacterial, reduces resistance; use with antibiotics; 2.5–5% often as effective as higher with less irritation; can bleach fabrics.
- Topical antibiotics: clindamycin or erythromycin ONLY in combination with BPO; avoid monotherapy.
- Other topicals: azelaic acid (comedonal/inflammatory, PIH benefit), dapsone 5–7.5% gel (adult female inflammatory acne), salicylic acid.
- Truncal acne: use washes (BPO) and lotions/foams for coverage.
- Systemic therapies
- Oral antibiotics (moderate–severe inflammatory acne): doxycycline/minocycline/sarecycline; combine with topical BPO/retinoid; limit to ~3 months then transition to maintenance; counsel on photosensitivity (doxycycline) and vestibular effects (minocycline), and antimicrobial stewardship.
- Hormonal therapies (female patients):
- Combined oral contraceptives (ethinyl estradiol with norgestimate, norethindrone acetate, drospirenone, etc.).
- Spironolactone 50–200 mg/day; monitor for hyperkalemia in at-risk patients; manage menstrual irregularities; counsel on teratogenicity and contraception.
- Oral isotretinoin
- Indications: severe nodulocystic acne, scarring/PIH risk, refractory moderate acne, significant psychosocial burden, acne fulminans variants.
- Dosing: ~0.5–1 mg/kg/day to cumulative 120–150+ mg/kg; lower-dose regimens effective with fewer side effects for some.
- Monitoring: pregnancy prevention programs (iPLEDGE/region-specific), lipids, LFTs; mucocutaneous xerosis, teratogenicity absolute; mood controversies—monitor symptoms; IBD risk not supported by most modern data.
- Avoid concomitant tetracyclines (pseudotumor cerebri risk).
- Special scenarios
- Acne in skin of color: prioritize irritation-minimizing regimens; azelaic acid for PIH; early scar/PIH prevention.
- Mask-related acne (maskne): gentle cleansing, non-occlusive moisturizers, BPO cleansers, treat underlying rosacea if present.
- Pregnancy: avoid retinoids, tetracyclines, spironolactone, isotretinoin. Use azelaic acid, BPO, topical clindamycin; consider oral erythromycin base or cephalexin if needed.
- Acne fulminans: systemic steroids plus isotretinoin under specialist care.
- Scar and sequelae management
- Early control to prevent scarring.
- For established scars: subcision, microneedling/RF, fractional lasers, TCA CROSS (icepick), fillers, punch excision; combine strategically.
- PIH: strict photoprotection, azelaic acid, retinoids; hydroquinone/kojic/other lighteners as appropriate.
References (recent guidelines and key reviews)
- AAD Acne Guidelines updates and stewardship statements, 2022–2024.
- European evidence-based acne guidelines, 2023–2024.
- Reviews on isotretinoin dosing strategies, antibiotic stewardship, and PIH in acne, 2021–2024.