The butterfly rash, also known as malar rash, is a classic dermatologic manifestation commonly associated with systemic lupus erythematosus (SLE). It typically presents as an erythematous, sharply demarcated rash distributed across the nasal bridge and bilateral malar eminences. However, similar rashes may also be observed in other dermatologic and systemic conditions. The rash can extend to involve the forehead, scalp, neck, and other sun-exposed areas. It is often photosensitive and may be exacerbated by ultraviolet (UV) radiation.

Clinical history and physical Examination

When evaluating a patient presenting with a butterfly rash, a thorough history and examination are essential:

History

Document the onset and duration of the rash, recent sun exposure, presence of rash elsewhere on the body, systemic symptoms such as weight loss or alopecia, and family history of autoimmune diseases. A detailed medication history should be obtained, specifically inquiring about drugs known to induce lupus-like syndromes (e.g., hydralazine, procainamide).

Physical Examination

 Inspect the rash for characteristics including macules, papules, pustules, scaling, edema, and pigmentation changes (hypo- or hyperpigmentation). Examine mucous membranes for ulcers or lesions and evaluate for associated findings such as conjunctival injection, nail fold capillary changes, lymphadenopathy, and signs of systemic involvement.

Differential diagnosis

Table 1 below summarizes medical causes of butterfly rash along with their key characteristics and associated signs/symptoms:

Investigations

• Immunologic tests: Antinuclear antibody (ANA), anti-double stranded DNA (anti-dsDNA), complement levels.

• Complete blood count (CBC): To evaluate for cytopenias.

• Urinalysis: To assess renal involvement.

• Liver function tests: If systemic involvement or medication toxicity suspected.

• Skin biopsy: May be performed for diagnostic confirmation.

Management and patient education

• Advise strict photoprotection, including avoidance of direct sunlight and regular application of broad-spectrum sunscreen.

• Recommend hypoallergenic cosmetics to cover facial lesions.

• Discontinue photosensitizing medications where possible.

• Educate patients on the chronic nature of the disease, potential systemic involvement, and the importance of regular follow-up.

• Referral to rheumatology and support groups such as the Lupus Foundation may be beneficial.

Special considerations in pediatrics

Butterfly rash is uncommon in children but may be seen in infectious conditions such as erythema infectiosum (fifth disease), characterized by the “slapped cheek” appearance.

References

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