Discoid Lupus Erythematosus

Discoid lupus erythematosus (DLE) is a disease of the skin causing atrophy, scarring and photosensitivity. It has sometimes been called chronic lupus erythematosis. It has features in common with systemic lupus erythematosus (SLE) but the latter is, as its name implies, a systemic disease that affects many internal organs. SLE has sometimes been called disseminated lupus erythematosus but this term is less apt and as it may also be abbreviated to DLE, it is best avoided.

Lupus is the Latin word for wolf, and it implies that the lesion resembles a wolf's bite. The term was originally used for lupus vulgaris that is cutaneous tuberculosis.

The prevalence is between 17 and 48 per 100,000 people. Women are affected about twice as often as men, compared with 10 times the frequency for SLE. The usual age of onset is between 20 and 40 years, which is about 20 years younger than SLE.

• The lesions are usually asymptomatic but they may present with mild pruritus or sometimes pain within the lesions.
• There may be accompanying SLE but this occurs in less than 5%.
• Arthralgia or arthritis can occur.

Appearance

The lesions have a characteristic appearance.

• Lesions tend to occur on skin that is most exposed to light but relatively unexposed skin may also be involved. The scalp is often affected and this may cause permanent alopecia.
• The primary lesion is an erythematous papule or plaque with slight or moderate scaling.
• With time, the scale may thicken and become adherent.
• Changes in pigmentation develop. The active border area shows hyperpigmentation whilst the inactive centre is hypopigmented.
• Lesions spread centrifugally and may merge.
• As lesions age, the follicular openings dilate and a keratin plug forms. This is called follicular plugging or patulous follicles.
• As active lesions resolve, atrophy and scarring results.

Subsets and variants

Patients with DLE often are divided into 2 subsets:

• Localised DLE is when the head and neck only are involved.
• Widespread DLE occurs when other areas are affected, even if the head and neck are also affected.

Those with widespread disease often have abnormalities of blood or serology, and are more likely to develop SLE. They are more difficult to treat.

Several unusual variants have been reported.

• Mucosal surfaces may be affected by lesions that appear identical to DLE of the skin or by lesions that may simulate lichen planus.
• Palms and soles may be affected in fewer than 2% of cases.
• DLE lesions may become hypertrophic or verrucous. There are wart-like lesions, most often on the extensor aspects of the arms. These hypertrophic lesions may resemble of LE warts, keratoacanthomas, or squamous cell carcinoma. They are difficult to treat.
• Lupus panniculitis is a chronic form that may be accompanied by typical DLE lesions or may occur in patients with SLE.

• Systemic lupus erythematosus
• Dermatomyositis
• Plaque psoriasis
• Actinic keratosis
• Lichen Planus
• Warts
• Sarcoidosis
• Squamous Cell Carcinoma
• Syphilis

There may be no laboratory tests giving abnormalities. Biopsy for histology may be required. Characteristic histopathological changes are observed in DLE but these differ depending upon the type and age of the lesion. About 90% of cases show a direct positive immunofluorescence in biopsies of lesions but this is not very specific.

• Serologic testing should be done. Approximately 20% of patients with DLE have a positive antinuclear antibody (ANA). A much smaller number are positive for other autoantibodies (1 to 3%).
• There may be a low white cell count and raised ESR.
• Rheumatoid factor may be positive.
• Complement levels may be low.
• Urinalysis may indicate renal involvement with albuminuria.

Blood tests should be repeated periodically, perhaps annually when the condition appears stable, to ascertain that systemic disease is not starting.

There are several skin diseases that occur more often in DLE.

• Malignant change may occur. Dark skin may loose its inherent protection with depigmentation. Malignant degeneration tends to produce basal cell carcinoma or squamous cell carcinoma rather than malignant melanoma.
• Porphyria cutanea tarda appears to be more common in patients with DLE but this may be precipitated by the use of antimalarials in the treatment of the disease.
• Lichen planus may be part of an overlap disease or may occur as a result of antimalarial therapy.
• Psoriasis is a common disease, but it may be more common in these patients.

The aims of management are to improve the patient's appearance, to control existing lesions and limit scarring, and to prevent the development of further lesions. Interpreting the literature can be difficult as papers often refer to the treatment of cutaneous manifestations of lupus erythematosus and it is unclear if the treated disease is SLE or DLE.

Non-drug

• Sun exposure must be minimised by avoiding going out in bright sun as much as possible, protective clothing and high factor sunscreens.
• The lesions are unsightly and usually in visible places, so cosmetic camouflage is required.
• There is no specific diet.
• Smoking should cease as it tends to be associated with more severe disease¹ and it makes treatment with antimalarials less effective.²

Drugs

The basis of drug treatment is topical or intralesional steroids and antimalarials.

• Corticosteroids may be used topically or intralesionally.
  • Weaker agents are required for the face.
  • Lotions or foams are preferred for the scalp.
  • Very potent forms are necessary for hypertrophic lesions.
  • Systemic steroids do not seem to be effective.
• Antimalarials are effective but less so in those who smoke.² When systemic treatment is required, hydroxychloroquine is the first line agent.
• Alternative therapies³ include auranofin, thalidomide,⁴ oral or topical retinoids, and immunosuppressive agents. The last are usually azathioprine or methotrexate.
• Topical calcineurin inhibitors have also been used recently.
• Picolimus appears promising.⁵
• There is very limited experience of topical imiquimod.
• Recently efalizumab has been studied and may be of use in patients with other similar forms of cutaneous lupus erythematosus but not specifically DLE.

Surgical

• Burned-out scarred lesions may be excised but reactivation has been reported in some cases.
• Laser therapy can be useful for prominent telangiectases but reactivation may also occur with this treatment.

The risk of conversion to SLE is greatest when lesions are extensive and severe and when there are abnormal haematological and serological parameters.

• Early treatment may reduce scarring or atrophy.
• Serious systemic disease is rare, but serious. It is more likely in extensive disease and with abnormal haematological and serological parameters.⁶
• Malignant degeneration is rare. Prompt removal of new growths within burned-out areas is advised.

The risk of mortality is low but pain in lesions may continue and disfiguration from scars and atrophy will be permanent.