Subacute Cutaneous Lupus Erythematosus

Subacute cutaneous lupus erythematosus (SCLE) is a photosensitive, non-scarring cutaneous lupus subset, strongly associated with anti-Ro/SSA antibodies, presenting as annular or papulosquamous lesions.

• Accounts for 10 to 15% of cutaneous lupus. Onset in the third to fifth decade; women predominate; most common in white people.
• Associated with Sjögren syndrome and SLE (about 50% meet at least 4 ACR criteria, but severe organ disease is uncommon).
• Drug induced SCLE: hydrochlorothiazide, terbinafine, calcium channel blockers (diltiazem), ACE inhibitors, proton pump inhibitors, antiepileptics, TNF inhibitors, immune checkpoint inhibitors, and griseofulvin.
• Maternal anti-Ro/La carries a risk of neonatal lupus (rash and congenital heart block) in 2% (up to 15 to 20% after a previously affected infant).

• Annular polycyclic or papulosquamous (psoriasiform) erythematous plaques on sun exposed areas: upper back, shoulders, extensor arms, neck, chest; face typically spared in the central region.
• Lesions heal with dyspigmentation and telangiectasia, but without scarring.
• Mild systemic features: arthralgia, fatigue, myalgia.
• Photosensitivity prominent; lesions may persist for weeks to months.

• Biopsy: interface dermatitis, epidermal atrophy, basal vacuolar degeneration, dermal mucin, and a superficial perivascular lymphocytic infiltrate; DIF granular IgG/IgM band in 50% (lesional).
• Serology: anti-Ro/SSA (70 to 90%), anti-La, ANA (60 to 80%), anti-dsDNA (less frequent), complement levels, FBC, creatinine, and urinalysis.
• Drug history in the preceding months.
• Exclude annular erythema, tinea corporis, psoriasis, erythema multiforme, and dermatomyositis; screen for SLE and Sjögren.

• Stop any suspected causative drug (resolves in weeks to months).
• Strict photoprotection: broad spectrum SPF 50+ sunscreens, hats, clothing.
• Topical: clobetasol 0.05% ointment twice daily for 2 to 4 weeks, or tacrolimus 0.1% ointment.
• Systemic: hydroxychloroquine 200 to 400 mg daily (5 mg/kg/day maximum) is first line; add quinacrine 100 mg daily if needed. Methotrexate 10 to 25 mg weekly, mycophenolate 1 to 2 g daily, thalidomide 50 to 100 mg daily, or dapsone 50 to 100 mg for resistant disease. Belimumab or anifrolumab if there is systemic SLE.
• Smoking cessation, vitamin D supplementation, and annual review for SLE.
• Pregnancy counselling: continue hydroxychloroquine; fetal echocardiography weekly from weeks 16 to 26 in anti-Ro positive mothers.