Discoid Lupus Erythematosus

What is it?

Discoid lupus erythematosus (DLE) is a chronic autoimmune skin condition that causes inflamed, disc-shaped (round or oval) patches on the skin. These patches typically appear on sun-exposed areas — the face, ears, and scalp — and heal with permanent scarring, loss of skin colour, and hair loss. DLE is the most common form of chronic cutaneous lupus erythematosus and is distinct from systemic lupus erythematosus (SLE), though a small proportion of patients may eventually develop systemic disease.

Who is affected?

DLE can affect anyone, but certain groups are more frequently affected.

• Prevalence: Approximately 6.5 per 100,000 people
• Age: Most commonly diagnosed between 20 and 40 years of age
• Sex: Women are affected 2–3 times more often than men
• Ethnicity: Significantly more common in people of African descent, who also tend to have more severe disease with greater scarring, pigmentary changes, and scalp involvement
• Risk factors: Sun exposure (ultraviolet light is the main trigger), smoking (worsens the disease and reduces treatment effectiveness), family history of autoimmune conditions

What causes it?

DLE is an autoimmune condition in which the immune system attacks the skin's own cells, particularly at the junction between the outer skin layer (epidermis) and the deeper layer (dermis).

• UV light trigger: Sunlight is the main environmental trigger; UV radiation damages skin cells, causing them to release proteins that activate the immune system
• Immune dysregulation: The body produces an excessive inflammatory response dominated by interferon (a type of immune signalling molecule), which sustains chronic inflammation
• Genetic predisposition: There is a familial tendency; certain gene variants involved in immune regulation increase susceptibility
• Smoking: A significant aggravating factor that worsens disease activity and reduces the effectiveness of antimalarial medications

What are the clinical features?

DLE typically presents as well-defined, round or oval patches on sun-exposed skin.

• Active lesions: Red or violaceous (purple-red) patches with adherent scale; when the scale is peeled off, small keratotic spines are visible on its undersurface (the "carpet tack sign")
• Follicular plugging: Visible filling of hair follicle openings with keratotic material, giving the skin a rough texture
• Scarring: As lesions heal, the centre becomes pale, atrophic (thinned), and depressed, with visible small blood vessels (telangiectasia)
• Pigmentary changes: Darkening (hyperpigmentation) at the active edges and lightening (hypopigmentation or depigmentation) in the centre — especially noticeable in darker skin types
• Scalp involvement: Causes permanent scarring hair loss (cicatricial alopecia); the affected areas are smooth, pale, and devoid of hair follicle openings
• Common locations: Face (cheeks, nose, ears), scalp, neck; less frequently on hands, arms, and trunk

Two patterns are recognized:

• Localized DLE (~80%): Lesions limited to the head and neck
• Generalized DLE (~20%): Lesions both above and below the neck; carries a higher risk of progression to systemic lupus

How is it diagnosed?

Diagnosis is based on the characteristic clinical appearance, confirmed by skin biopsy.

• Clinical examination: Well-defined, disc-shaped plaques with scale, follicular plugging, scarring, and pigmentary changes in a sun-exposed distribution
• Dermoscopy: Reveals follicular keratotic plugs, white structureless areas, branching (arborizing) vessels, and speckled brown pigmentation
• Skin biopsy: Shows interface dermatitis (inflammation at the junction between epidermis and dermis), follicular plugging, thickening of the basement membrane, and mucin deposits in the dermis
• Direct immunofluorescence (lupus band test): Demonstrates a band of immunoglobulin and complement deposits at the dermal-epidermal junction; in DLE, positive only in lesional skin
• Blood tests: ANA (antinuclear antibodies) is positive in approximately 20–30% of patients with skin-limited DLE; full blood count, renal function, and urinalysis are checked to screen for systemic lupus

What treatment options are available?

Treatment aims to control inflammation, prevent new lesions, and minimize scarring. Early treatment is essential — once scarring occurs, it is permanent.

Sun protection (essential for all patients):

• Broad-spectrum sunscreen (SPF 50+) applied daily, reapplied every 2 hours when outdoors
• Protective clothing, wide-brimmed hats, avoidance of peak sun hours
• Smoking cessation — smoking reduces the effectiveness of treatment

For localized disease:

• High-potency topical corticosteroids (clobetasol propionate 0.05%) applied to active lesions
• Topical calcineurin inhibitors (tacrolimus 0.1%) — preferred for facial lesions to avoid skin thinning from corticosteroids
• Intralesional corticosteroid injections (triamcinolone acetonide 3–5 mg/mL) for resistant plaques

For widespread or resistant disease:

• Hydroxychloroquine 200–400 mg daily — the mainstay systemic treatment; may take 2–3 months for full effect
• Methotrexate 10–25 mg weekly — for patients who do not respond to hydroxychloroquine
• Other options for refractory cases: mycophenolate mofetil, thalidomide, retinoids

Prognosis: DLE is a chronic condition that tends to wax and wane, often worsening with sun exposure. With consistent treatment and sun protection, most patients achieve good disease control. However, scarring and pigmentary changes are permanent. Approximately 5% of patients with localized DLE may develop systemic lupus erythematosus, rising to up to 20–28% in generalized DLE.

Key points for patients

• DLE is not contagious — it is an autoimmune condition
• Sun protection is the single most important measure you can take to prevent flares
• Smoking significantly worsens the disease — cessation is strongly recommended
• Early treatment prevents permanent scarring and hair loss
• When to seek medical attention: New or expanding patches; any non-healing ulcer or nodule within an old scar (small risk of skin cancer in longstanding lesions); joint pain, fatigue, or mouth ulcers that could suggest systemic lupus
• Regular follow-up with a dermatologist is important to monitor disease activity and screen for systemic involvement
• There is a small but real risk (2–3%) of squamous cell carcinoma developing in chronic, longstanding DLE scars — report any new growth or ulceration in an old lesion