Dermatology, Venereology and Leprosy
Acne Vulgaris
Acne vulgaris for MBBS and NEET-PG: pilosebaceous pathogenesis, comedonal to nodulocystic grading, topical retinoids, oral antibiotics and isotretinoin, mapped to NMC codes DR1.
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Acne Vulgaris
Acne vulgaris for MBBS and NEET-PG: pilosebaceous pathogenesis, comedonal to nodulocystic grading, topical retinoids, oral antibiotics and isotretinoin, mapped to NMC codes DR1.
Acne vulgaris is the commonest skin disorder of adolescence and a frequent examination topic. This chapter covers the pilosebaceous pathogenesis, the recognition and grading of comedonal, inflammatory and nodulocystic lesions, and a treatment ladder that runs from topical retinoids to oral isotretinoin.
High-yield: Acne Vulgaris
- Acne vulgaris is a disease of the pilosebaceous unit and is commonest over the face, chest and back where sebaceous glands are dense.
- The four pathogenic factors are increased sebum production, follicular hyperkeratinisation, Cutibacterium acnes colonisation and inflammation.
- Androgens drive sebum output, which is why acne begins around puberty and worsens in conditions of hyperandrogenism.
- The open comedone is the blackhead and the closed comedone is the whitehead, and comedones are the non-inflammatory primary lesions.
- Inflammatory lesions run in a sequence of papules, pustules, nodules and cysts as severity increases.
- Acne is graded as mild (comedonal), moderate (papulopustular) and severe (nodulocystic), and grading guides treatment.
- Topical retinoids such as adapalene and tretinoin are comedolytic and are the mainstay for comedonal acne.
- Benzoyl peroxide is bactericidal against Cutibacterium acnes and reduces the risk of antibiotic resistance when combined with topical antibiotics.
- Moderate inflammatory acne is treated with oral tetracyclines such as doxycycline or minocycline, avoided in children under 8 and in pregnancy.
- Oral isotretinoin is reserved for severe nodulocystic or scarring acne and is strongly teratogenic, so two forms of contraception and pregnancy testing are mandatory.
- Isotretinoin also causes dry lips and skin, raised transaminases and dyslipidaemia, needing baseline and follow-up blood tests.
- Combined oral contraceptives and anti-androgens such as spironolactone help acne in women, especially where hormonal features are present.
- Sudden severe acne with irregular menses and hirsutism should prompt a search for polycystic ovary syndrome or another cause of hyperandrogenism.
- Post-inflammatory hyperpigmentation and scarring are the main long-term complications, so early effective treatment is preventive.
Grading acne and its treatment
- **Mild (comedonal):** Open and closed comedones. Topical retinoid, benzoyl peroxide.
- **Moderate (papulopustular):** Inflammatory papules and pustules. Add topical or oral antibiotic.
- **Severe (nodulocystic):** Nodules, cysts, scarring. Oral isotretinoin under monitoring.
- **Hormonal in women:** Combined oral contraceptive or spironolactone; screen for PCOS.
NMC competencies in this chapter
- **DR1.1:** Causative and risk factors of acne
- **DR1.2:** Identifying and grading the common types of acne
- **DR1.3:** Treatment and preventive measures for the various kinds of acne
Frequently Asked Questions
What are the four factors that cause acne?
Increased sebum production, blockage of the follicle by abnormal keratinisation, colonisation with Cutibacterium acnes and the resulting inflammation. Androgens at puberty trigger the increased sebum.
When is oral isotretinoin used?
For severe nodulocystic or scarring acne that has failed other treatment. It is strongly teratogenic, so pregnancy must be excluded and reliable contraception used, with monitoring of liver enzymes and lipids.
What is the difference between a blackhead and a whitehead?
A blackhead is an open comedone whose surface keratin has oxidised and darkened, while a whitehead is a closed comedone with an intact overlying surface. Both are non-inflammatory comedones.
When should acne prompt a hormonal work-up?
Sudden severe acne with irregular periods, excess hair growth or other virilising features suggests hyperandrogenism such as polycystic ovary syndrome and warrants investigation.
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