Rosacea is one of those “looks like acne but isn’t acne” diagnoses that Step loves—because the clues are subtle, the triggers are classic, and the treatment is very pattern-based. If you can recognize the phenotype (erythema/flushing ± papules/pustules ± ocular symptoms) and remember what shouldn’t be present (comedones), you’ll get most rosacea questions right.
What Is Rosacea?
Rosacea is a chronic inflammatory facial dermatosis characterized by episodic flushing and/or persistent central facial erythema, often with telangiectasias and sometimes papules/pustules.
High-yield defining features
- Central face: cheeks, nose, chin, forehead
- Flushing + persistent erythema
- Telangiectasias
- Papules/pustules may occur
- No comedones (distinguishes from acne vulgaris)
Pathophysiology (What Step 1 Cares About)
Rosacea is not fully understood, but Step-relevant mechanisms cluster into a few buckets:
1) Innate immune dysregulation
- Increased inflammatory mediators in the skin (e.g., abnormal cathelicidin processing), promoting:
- Vasodilation
- Neutrophilic inflammation
- Skin sensitivity
2) Neurovascular hyperreactivity
- Exaggerated vasodilation response → flushing and persistent erythema
- Triggers activate neurogenic inflammation (burning/stinging symptoms are common)
3) Microbial associations (testable, not definitive “cause”)
- Demodex folliculorum overgrowth is associated with some cases (especially papulopustular disease)
- H. pylori association is sometimes cited (less consistently supported), but still appears in test-prep contexts
4) Chronic inflammation → tissue remodeling
- Longstanding inflammation can cause phymatous changes (thickened skin), classically:
- Rhinophyma (bulbous nose)
Clinical Subtypes & Presentation (Pattern Recognition)
Rosacea is often described in phenotypes/subtypes. Patients can have overlap.
Erythematotelangiectatic rosacea
- Persistent central facial erythema
- Flushing
- Telangiectasias
- Burning/stinging, sensitive skin
Papulopustular rosacea
- Erythema + papules/pustules
- NO comedones (key)
- Often mistaken for acne
Phymatous rosacea
- Skin thickening, irregular surface
- Rhinophyma (nose)
- Classically in older men, but can occur in anyone
Ocular rosacea (very high yield)
- Dry, gritty, burning eyes
- Blepharitis
- Conjunctivitis
- Recurrent styes/chalazia
- Can threaten vision if severe/untreated
Triggers (Step-Friendly List)
Common triggers cause flushing and symptom flares:
- Heat, hot showers
- Hot beverages
- Spicy foods
- Alcohol (esp. red wine)
- Sun/UV exposure
- Exercise
- Emotional stress
- Harsh skin products/topicals
- Vasodilating meds can worsen flushing in some patients
Board-style clue: “Middle-aged adult with facial flushing that worsens with hot drinks/spicy food and has telangiectasias.”
Diagnosis
Mostly clinical
Rosacea is a clinical diagnosis based on distribution + morphology + triggers.
Classic exam vignette
- Central facial erythema + telangiectasias ± papules/pustules
- Flushing triggered by heat/alcohol/spicy foods
- No comedones
When to think “not rosacea”
Consider alternatives when there are systemic findings or different morphology/distribution:
| Condition | Key clues vs rosacea |
|---|---|
| Acne vulgaris | Comedones (open/closed), broader distribution (back/chest), less flushing-trigger pattern |
| SLE malar rash | Spares nasolabial folds often, photosensitive, systemic symptoms; no pustules/telangiectasias pattern |
| Seborrheic dermatitis | Greasy scale, eyebrows/nasolabial folds/scalp involvement |
| Perioral dermatitis | Perioral papules, often spares vermilion border; often steroid-triggered |
| Carcinoid syndrome | Flushing + diarrhea/bronchospasm; systemic signs |
| Topical steroid rosacea | History of chronic topical steroid use; rebound erythema/papules |
Tests?
- Usually none needed.
- If prominent ocular symptoms → consider ophthalmology evaluation.
Treatment (Algorithmic + High Yield)
Rosacea management is two-part: avoid triggers + targeted therapy based on phenotype.
Step 1: Lifestyle & skin care (always)
- Trigger avoidance (heat, alcohol, spicy foods, hot drinks, sun)
- Gentle cleanser, moisturizer
- Daily sunscreen (often mineral sunscreens better tolerated)
Step 2: Medical therapy by phenotype
Persistent erythema/flushing
- Topical brimonidine (alpha-2 agonist) or oxymetazoline (alpha-1 agonist): reduces erythema via vasoconstriction
- HY pearl: these treat erythema, not papules/pustules
Papules/pustules (most tested pharm)
- Topical metronidazole (classic Step answer)
- Azelaic acid
- Ivermectin topical (ties to Demodex association)
- If moderate–severe: oral doxycycline (anti-inflammatory dosing often used)
Phymatous changes (e.g., rhinophyma)
- Medical therapy may help early, but often needs:
- Laser therapy or surgical debulking
Ocular rosacea
- Lid hygiene, artificial tears
- Oral doxycycline for anti-inflammatory effect
- Ophthalmology referral if significant symptoms
What to avoid / pitfalls
- Topical corticosteroids can worsen rosacea long-term and cause steroid rosacea-like flares.
- Isotretinoin is not first-line for typical rosacea (can be considered in refractory cases, but Step usually wants metronidazole/doxycycline).
High-Yield Associations & “Classic Clues”
Rosacea vs acne: the Step differentiator
- Rosacea: flushing + central facial erythema + telangiectasias, no comedones
- Acne: comedones + inflammatory lesions; typically adolescents; chest/back common
Rosacea and rhinophyma
- Rhinophyma is phymatous rosacea → thickened, bulbous nose from chronic inflammation.
- Don’t confuse with acute “red nose from alcohol” stereotypes; alcohol can be a trigger but does not cause rosacea.
Ocular findings
- If the question mentions recurrent chalazia/styes, blepharitis, or “gritty eyes” in someone with facial erythema → think ocular rosacea.
Demodex association
- If you see rosacea-like papulopustules with a hint about mites or “follicular infestation,” rosacea + Demodex may be the intended link (topical ivermectin).
First Aid Cross-References (Where It Fits)
First Aid typically places rosacea in the Dermatology section among acneiform and inflammatory facial eruptions. Cross-link it mentally with:
- Acne vulgaris (comedones; Propionibacterium/Cutibacterium acnes; isotretinoin side effects)
- Seborrheic dermatitis (greasy scale in nasolabial folds/scalp)
- SLE malar rash (photosensitivity/systemic autoimmunity)
- Perioral dermatitis (often steroid-induced, papules around mouth)
Memory anchor: “Rosacea = redness + reactivity (flushing) + telangiectasias; treat with metronidazole/doxycycline; no comedones.”
Rapid Review (Exam-Day Bullets)
- Definition: Chronic inflammatory disorder causing central facial flushing/erythema ± telangiectasias ± papules/pustules
- Key negative: No comedones
- Triggers: heat, alcohol, spicy foods, hot drinks, sun, stress
- Ocular: blepharitis, conjunctivitis, gritty eyes, recurrent chalazia
- Tx (most HY):
- Topical metronidazole (papulopustular)
- Oral doxycycline (moderate–severe and ocular)
- Brimonidine/oxymetazoline for persistent erythema
- Complication: Rhinophyma