Write a short note on acne vulgaris.

Definition

Acne vulgaris is a chronic inflammatory disorder of the pilosebaceous unit, characterised by comedones, papules, pustules, nodules and, in severe cases, scarring. It affects up to 85% of adolescents, typically beginning at puberty with the rise in androgens, and may persist into adult life, particularly in women.

Pathogenesis — Four Factors

1. Increased sebum production driven by androgens acting on sebaceous glands at puberty.

2. Follicular hyperkeratinisation — abnormal keratinocyte proliferation and adhesion obstructs the follicular opening, forming the microcomedone, the precursor of all acne lesions.

3. Colonisation by *Cutibacterium acnes* (formerly *Propionibacterium acnes*), which hydrolyses sebum triglycerides to free fatty acids and activates innate immunity.

4. Inflammation — release of IL-1, TNF-α and neutrophil chemotaxis produces the papules, pustules and nodules; rupture of the follicle into the dermis causes the deep inflammatory lesions that scar.

Aggravating factors: cosmetics and hair oils (pomade acne, common in India), mechanical occlusion and friction (helmets, chin straps), humidity, stress, and drugs — corticosteroids, anabolic steroids, lithium, isoniazid, phenytoin, ciclosporin, iodides.

Clinical Features

Distribution: face, forehead, chest, upper back and shoulders — the sites of greatest sebaceous gland density.

Lesions:

• Non-inflammatory: open comedones (blackheads) — the black colour is oxidised melanin, not dirt; and closed comedones (whiteheads).
• Inflammatory: papules, pustules, and in severe disease nodules and cysts with sinus tract formation.
• Sequelae: post-inflammatory hyperpigmentation — particularly prominent and distressing in Indian skin, often the presenting complaint rather than the acne itself; and scarring — ice-pick, boxcar, rolling, and hypertrophic or keloidal scars.

Grading:

• mild (comedonal), moderate (papulopustular), severe (nodulocystic).
• Acne conglobata is severe nodulocystic disease with interconnecting sinuses
• acne fulminans adds fever, arthralgia and systemic upset.

Investigations

Acne is a clinical diagnosis and needs no investigation in most cases. Investigate for hyperandrogenism — testosterone, DHEAS, LH:FSH ratio, pelvic ultrasound — where there is sudden-onset severe acne in an adult woman with hirsutism, irregular menses, androgenic alopecia or obesity, suggesting polycystic ovary syndrome or, rarely, an androgen-secreting tumour or congenital adrenal hyperplasia.

Management

Treatment is directed at the four pathogenic factors, and must be continued for at least 8–12 weeks before judging response — a point patients must be told, since premature abandonment is the commonest reason for failure.

General measures: gentle cleansing twice daily (vigorous scrubbing worsens inflammation), non-comedogenic oil-free cosmetics, avoiding hair oils on the forehead, and discouraging picking and squeezing, which causes scarring. Address the psychological impact — acne carries a well-documented burden of anxiety, depression and social withdrawal in adolescents.

Isotretinoin — a systemic retinoid that addresses all four pathogenic factors and is the only agent that produces prolonged remission. Adverse effects include cheilitis, xerosis, dry eyes, myalgia, raised transaminases and triglycerides, and photosensitivity.