Discoid Lupus Erythematosus

What is discoid lupus erythematosus?

Discoid lupus erythematosus (DLE) is a chronic photosensitive skin eruption which can be either localised or widespread. It is confined to the skin and does not cause any systemic symptoms. DLE can cause permanent scarring if treatment is inadequate.

How common is discoid lupus erythematosus? (Epidemiology)

• The prevalence is between 17 and 48 per 100,000 people.
• Women are much more often affected than men.
• DLE usually presents in people aged between 20 and 40 years of age.
• DLE is more common in smokers.^[1]
• DLE can be present in a small proportion of patients with systemic lupus erythematosus (SLE).^[2]

Discoid lupus erythematosus symptoms^[3]

• Localised DLE commonly involves the head and neck, and particularly the scalp and ears.
• Generalised DLE, which occurs both above and below the neck, is less common and typically involves the extensor forearms and hands.
• Occasionally, DLE can occur on mucosal surfaces, including lips, and oral, nasal, and genital mucosa.
• DLE lesions appear as a well-demarcated, scaly, erythematous macule or papule, which gradually develops into an indurated discoid (coin-shaped) plaque with an adherent scale that is painful to remove.
• Plaques tend to extend into the hair follicle, resulting in scarring alopecia.
• These lesions typically become atrophic, with hyperpigmentation peripherally and depigmentation centrally.
• Sun exposure or trauma (Koebner phenomenon) can exacerbate disease.

Differential diagnosis^[3]

• SLE.
• Dermatomyositis.
• Plaque psoriasis.
• Actinic keratosis.
• Lichen planus.
• Warts.
• Sarcoidosis.
• Squamous cell carcinoma.
• Cutaneous T-cell lymphoma.
• Syphilis.

Investigations

• The diagnosis of DLE is usually based on clinical features.
• Biopsy for histology may be required.
• Histopathological changes are characteristic but depend on the type and age of the lesion.
• Most patients with DLE show a direct positive immunofluorescence in biopsies of lesions.^[4]
• Serology: approximately 20% of patients with DLE have a positive antinuclear antibody (ANA).
• There may be a low white cell count and raised ESR.
• Complement levels may be low.
• Urinalysis may indicate renal involvement with albuminuria.

Blood tests should be repeated periodically, usually annually when the condition appears stable, to check for the onset of systemic disease.

Discoid lupus erythematosus treatment and management^{[3, 5]}

The mainstay of treatment includes sun protection, topical or intralesional steroids and antimalarial drugs.

Non-drug

• Sun exposure must be minimised by avoiding going out in bright sun as much as possible and by wearing protective clothing and high-factor sunscreens.
• The lesions are unsightly and usually in visible places, so cosmetic camouflage is required.

Drugs

• Topical therapies, including steroids and/or calcineurin inhibitors (eg, tacrolimus).
• Corticosteroids may be used topically or intralesionally. Very potent forms are necessary for hypertrophic lesions.
• Fluocinonide cream may be more effective than hydrocortisone in clearing DLE skin lesions.
• When systemic treatment is required, antimalarial drugs, such as hydroxychloroquine, are the usually the first-line choice. Systemic steroids are generally avoided because of potential side effects.
• Topical imiquimod cream is an alternative treatment for generalised DLE.^[6]
• Other possible treatments include topical retinoids and immunosuppressive agents (eg, azathioprine or mycophenolate).
• Further options if needed include biologics (eg, rituximab), dapsone, or oral retinoids (eg, acitretin or isotretinoin).

Surgical

• Burned-out scarred lesions may be excised.
• Photodynamic therapy can be effective for some cases.^[7]
• Laser therapy can be considered for lesions with prominent telangiectasias.

Complications

• A minority of patients with DLE (fewer than 5%) progress to SLE.
• In paediatric patients, however, DLE carries a significant risk of progression to SLE but may predict a milder phenotype of systemic disease.^[8]
• The presence of DLE in patients with SLE has not been shown to be associated with less severe disease.^[9]
• There are increased risks of photosensitivity and leukopenia and decreased risks of pleuritis and arthritis in patients with both SLE and DLE.^[2]
• Malignant degeneration (basal cell carcinoma or squamous cell carcinoma) may occur but is uncommon.^[10]
• Dark skin may lose its inherent protection with depigmentation.

Prognosis^[3]

• DLE generally has a more benign disease course compared to other forms of cutaneous lupus, with only a reported 5-10% developing SLE throughout their disease course.
• Generalised DLE is more likely to progress to systemic disease, compared to patients with localised DLE.
• Pain in lesions may continue and disfiguration from scars and atrophy will be permanent.
• DLE tends to heal with scarring, hair loss and pigmentary changes if treatment is not initiated in the early phase of the disease.