How should I evaluate and manage a patient presenting with a malar (butterfly) rash?

Evaluation and Management of Malar (Butterfly) Rash

A malar rash is a hallmark cutaneous manifestation of acute cutaneous lupus erythematosus (ACLE) and should prompt immediate evaluation for systemic lupus erythematosus (SLE), as it appears in approximately 51% of SLE patients and often indicates active systemic disease. 1, 2

Initial Clinical Assessment

Key Historical Features to Elicit

• Photosensitivity history – Present in 63% of SLE patients and often worsens the malar rash 2
• Systemic symptoms – Fever, fatigue, arthralgias, or myalgias suggesting multisystem involvement 1
• Medication history – Certain drugs can induce subacute cutaneous LE with similar facial involvement 1
• Duration and evolution – Acute onset versus chronic progression helps differentiate ACLE from chronic forms 3
• Associated symptoms – Oral ulcers (present in 31.5% at some point), alopecia (40%), or Raynaud's phenomenon (60%) 2

Physical Examination Specifics

Characterize the malar rash morphology:

• Classic butterfly distribution – Erythematous macules, papules, or plaques over the malar eminences and nasal bridge, characteristically sparing the nasolabial folds 1, 2
• Associated features – Look for telangiectasia, facial edema (5% of cases), or papulosquamous changes 2
• Scarring assessment – ACLE typically does not scar, unlike chronic discoid LE which causes atrophic scarring 4

Complete skin examination for additional LE-specific lesions:

• Discoid lesions – Round/oval erythematous plaques with scales and follicular plugging on scalp, face, ears (present in 25% of SLE patients) 2, 4
• Subacute cutaneous LE – Psoriasiform or annular lesions on upper back, shoulders, chest (7% of cases) 2
• Chilblain lupus – Violaceous lesions on acral sites (20.5% in British populations) 2

Assess for non-specific manifestations:

• Vascular signs – Livedo reticularis, cutaneous vasculitis, periungual telangiectasia 1, 2
• Hair and nails – Non-scarring alopecia (40%), scarring alopecia from discoid lesions (14%) 2
• Mucosal involvement – Oral ulcers, palatal erythema, or buccal plaques 2

Diagnostic Workup

Laboratory Evaluation

Initial serologic testing:

• Antinuclear antibody (ANA) – Screening test for SLE 1
• Anti-dsDNA and anti-Smith antibodies – Highly specific for SLE 1
• Anti-Ro/SSA antibodies – Frequently positive in subacute cutaneous LE and photosensitive variants 1
• Complete blood count – Assess for cytopenias associated with SLE 1
• Comprehensive metabolic panel – Evaluate renal function 1
• Urinalysis – Screen for proteinuria or cellular casts indicating lupus nephritis 1
• Complement levels (C3, C4) – Low levels suggest active systemic disease 1

Skin Biopsy Considerations

Perform punch biopsy when:

• Diagnosis remains uncertain after initial evaluation 1
• Differentiating between LE subtypes is necessary for prognosis 3
• Atypical presentations require histopathologic confirmation 5

Biopsy technique:

• Sample from active lesion edge, not center 1
• Submit for routine histopathology and direct immunofluorescence 1

Management Algorithm

Step 1: Photoprotection (All Patients)

• Broad-spectrum sunscreen with SPF ≥50, applied liberally and reapplied every 2 hours during sun exposure 1
• Physical sun avoidance – Protective clothing, wide-brimmed hats, seeking shade 1
• Avoid peak UV hours (10 AM to 4 PM) 1

Step 2: Topical Therapy (First-Line for Localized Disease)

• High-potency topical corticosteroids – Apply to affected areas once or twice daily 1
• Topical calcineurin inhibitors (tacrolimus, pimecrolimus) – Alternative for facial lesions to avoid steroid atrophy 1

Step 3: Systemic Antimalarials (When Topical Therapy Insufficient)

Hydroxychloroquine is the preferred first-line systemic agent:

• Dosing: 200-400 mg daily (≤5 mg/kg/day actual body weight) 1
• Monitoring: Baseline and annual ophthalmologic examination for retinal toxicity 1
• Expected response: Improvement typically seen within 6-12 weeks 1

Step 4: Additional Systemic Therapies (Refractory Cases)

When antimalarials fail or are contraindicated:

• Methotrexate – 10-25 mg weekly with folic acid supplementation 1
• Systemic corticosteroids – Short courses for acute flares, minimize chronic use 1
• Azathioprine – 1-2.5 mg/kg/day for steroid-sparing effect 1
• Thalidomide – 50-100 mg daily (highly effective but requires strict pregnancy prevention) 1
• Dapsone – 50-200 mg daily (check G6PD before initiating) 1

Newer immunomodulatory agents for severe refractory disease:

• Rituximab – Anti-CD20 monoclonal antibody 1
• Intravenous immunoglobulin 1
• Biologic agents – Consider in consultation with rheumatology 1

Critical Pitfalls to Avoid

• Do not dismiss malar rash as simple rosacea or dermatitis – The butterfly distribution sparing nasolabial folds is highly characteristic of ACLE and warrants full SLE workup 1, 2
• Do not delay systemic evaluation – Malar rash often indicates active systemic disease requiring prompt multisystem assessment 3
• Do not assume isolated cutaneous disease – Even patients presenting with only skin findings require screening for systemic involvement, as 51% of SLE patients have malar rash 2
• Do not overlook drug-induced lupus – Obtain thorough medication history including recent additions 1
• Do not confuse with chronic discoid LE – ACLE (including malar rash) does not scar, while discoid lesions cause permanent atrophic scarring with dyspigmentation 4

Prognosis and Follow-Up

• Patients with isolated malar rash have variable risk of progression to SLE – Close monitoring with serial serologic testing is essential 3
• Coordinate care with rheumatology when systemic features are present or serologies are positive 3
• Regular dermatologic follow-up ensures disease control and prevents permanent damage from scarring variants 3
• Monitor for treatment complications – Particularly retinal toxicity with hydroxychloroquine and teratogenicity with thalidomide 1