Overview
Both acne vulgaris and rosacea are common facial skin conditions but have distinct etiologies, age groups, and treatments. Recognising differences is essential for diagnosis and PLAB-style vignettes.
Comparison Table
| Feature | Acne Vulgaris | Rosacea |
|---|---|---|
| Etiology | Follicular hyperkeratinization + Propionibacterium acnes inflammation | Chronic inflammatory disorder; dysregulation of innate immunity and vascular reactivity; triggers include UV, heat, alcohol, spicy food |
| Age group | Adolescents (12–25 years) | Adults 30–50 years |
| Distribution | Face (T-zone), chest, back | Central face: cheeks, nose, forehead, chin |
| Lesion type | Comedones (open/closed), papules, pustules, cysts | Papules, pustules, erythema, telangiectasia; no comedones |
| Triggers | Hormonal changes, oily skin, cosmetics | Sun, heat, alcohol, spicy food, hot drinks, stress |
| Symptoms | May be tender or nodular | Burning, stinging, flushing |
| Complications | Scarring, post-inflammatory hyperpigmentation | Rhinophyma (severe chronic nasal thickening), ocular rosacea |
| Management (Topical) | Benzoyl peroxide, retinoids, topical antibiotics (clindamycin) | Metronidazole, azelaic acid, ivermectin |
| Management (Systemic) | Oral antibiotics (doxycycline, minocycline), hormonal therapy, isotretinoin | Oral antibiotics (tetracyclines) for severe or ocular rosacea; isotretinoin in refractory cases |
| Key Exam Clues | Presence of comedones | Absence of comedones + flushing, telangiectasia |
PLAB Tips
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Comedones = acne vulgaris; no comedones + central facial erythema = rosacea.
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Rosacea triggers: sun exposure, alcohol, spicy foods, hot drinks.
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Acne in adults may be hormonal (women: menstrual cycle, PCOS).
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Ocular rosacea: redness, irritation, photophobia; may require ophthalmology referral.
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Severe acne nodules/cysts → systemic isotretinoin; monitor LFTs, pregnancy status.
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Rosacea management focuses on anti-inflammatory and trigger avoidance.
PLAB-Style Questions
Q1: A 35-year-old woman presents with central facial erythema, papules, pustules, and visible telangiectasia. No comedones are seen. What is the most likely diagnosis?
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A. Acne vulgaris
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B. Rosacea
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C. Seborrheic dermatitis
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D. Folliculitis
✅ Answer: B. Rosacea
Q2: A 16-year-old teenager presents with comedones, papules, and pustules on the forehead, nose, and chin. What is the first-line topical treatment?
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A. Topical metronidazole
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B. Benzoyl peroxide
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C. Oral tetracycline
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D. Topical corticosteroids
✅ Answer: B. Benzoyl peroxide
High-Yield Pearls
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Acne vulgaris: adolescents, comedones, T-zone, scarring possible.
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Rosacea: adults, central facial erythema, papules/pustules, no comedones, trigger-sensitive.
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Systemic therapy: isotretinoin for severe acne; tetracyclines for moderate/severe rosacea.
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Always assess ocular involvement in rosacea.
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PLAB exam tip: presence or absence of comedones is often the key differentiator in vignettes.
