Acne Vulgaris: Pathogenesis, Clinical Types, and Evidence-Based Management

Acne Vulgaris: The Medical Term for "Pimples"

A chronic inflammatory disease of the pilosebaceous unit (hair follicle + sebaceous gland). Affects 85% of adolescents; persists into adulthood for many.

Pathogenic Pillars

1. Sebum overproduction: Androgen-driven (puberty, PCOS, stress).
2. Follicular hyperkeratinization: Abnormal desquamation → microcomedone.
3. Cutibacterium acnes proliferation: Anaerobe thrives in lipid-rich, hypoxic follicle.
4. Inflammation: C. acnes activates TLR2 → cytokines (IL-1, TNF-α) → immune influx.

Lesion Morphology

• Non-inflammatory: Open comedone (blackhead), closed comedone (whitehead).
• Inflammatory: Papule, pustule, nodule, cyst (deep, >5 mm, scarring risk).

Grading & Treatment Algorithm

Severity	First-Line	Add/Escalate
Mild (comedonal ± few papules)	Topical retinoid (adapalene 0.1/0.3%) ± BP	Azelaic acid, topical antibiotic
Moderate (papulopustular)	Topical retinoid + BP ± topical antibiotic (clindamycin/erythro)	Oral doxycycline/minocycline 50–100 mg q12h × 12 wks
Severe (nodulocystic, scarring)	Oral isotretinoin 0.5–1 mg/kg/day × 16–24 wks	Intralesional steroid, incision/drainage

Key Principles

• Combination therapy targets multiple pathways.
• Retinoids are maintenance backbone (prevent microcomedones).
• Limit oral antibiotics to 3–4 months; always pair with BP to reduce resistance.
• Isotretinoin: iPLEDGE (US), pregnancy prevention mandatory, monitor LFTs/lipids.
• Adjuncts: Gentle cleanser, non-comedogenic moisturizer, sunscreen.