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.

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 erythematosis (SLE).^[2]

Presentation

• Red scaly patches develop which leave pigmentation, atrophy and white scars.
• The lesions are usually asymptomatic but they may present with mild pruritus or sometimes pain within the lesions.
• DLE mainly affects areas exposed to sunlight, such as the cheeks, nose, ears, upper back, neck and the backs of hands. It may rarely occur on the palms or soles.
• DLE lesions may become hypertrophic, causing wart-like lesions, most often on the extensor aspects of the arms.
• The scalp may be affected and cause permanent scarring alopecia.
• DLE may affect the lips and inside the mouth, causing ulcers and scaling.

Discoid lupus

Differential diagnosis

• SLE
• Dermatomyositis
• Plaque psoriasis
• Actinic keratosis
• Lichen planus
• Warts
• Sarcoidosis
• Squamous cell carcinoma
• 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.^[3]
• 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.

Management

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

• Corticosteroids may be used topically or intralesionally:
  • Very potent forms are necessary for hypertrophic lesions.
  • Systemic steroids do not seem to be effective.
• When systemic treatment is required, hydroxychloroquine is the usually the first-line agent.
• Topical imiquimod cream is an alternative treatment for generalised DLE.^[4]
• Other possible treatments include topical retinoids and immunosuppressive agents (eg, azathioprine or methotrexate).

Surgical

• Burned-out scarred lesions may be excised.
• Photodynamic therapy can be effective for some cases.^[5]
• 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.^[6]
• The presence of DLE in patients with SLE has not been shown to be associated with less severe disease.^[7]
• 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.^[8]
• Dark skin may lose its inherent protection with depigmentation.

Prognosis

• 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.