Lupus erythematosus (LE):

lupus erythematosus
There are three clinical variants to this disease but some patients may show features of more than one type.
chronic discoid lupus erythematosus (CDLE)
subacute lupus erythematosus (SCLE)
systemic lupus erythematosus (SLE).
The aetiology is unknown but is due to abnormality in immune function as variable autoantibodies may be found in all types. Very rarely it can be induced by certain drugs such as phenothiazines, hydralazine, methyldopa, isoniazid, tetracycline, mesalazine and penicillin.
Chronic discoid lupus erythematosus (CDLE)
CDLE is the most common type of LE seen by dermatologists and more frequently affects females. Clinically it presents with fixed erythematous, scaly, atrophic plaques with telangiectasia, especially on the face or other sun-exposed sites (Fig. 23.25). Hypopigmentation is common and follicular plugging occurs. Scalp involvement leads to a scarring alopecia. Oral involvement (erythematous patches or ulceration) occurs in 25% of cases.
CDLE can be triggered and exacerbated by UV exposure. A few patients also suffer with Raynaud's phenomenon or unusual chilblain-like lesions (chilblain lupus). Only 5% of cases will go on to develop SLE but this is more common in children. Serum antinuclear antibody (ANA) is positive in 30% of cases.

Skin biopsy shows a dense patchy, dermal lymphohistiocytic infiltrate which often is centred on appendages. Epidermal basal layer damage, follicular plugging and hyperkeratosis may be present. Direct immunofluorescence studies of lesional skin may show the presence of IgM and C3 at the dermoepidermal junction ('lupus band').
Treatment
First-line therapy is with sunscreens and potent topical steroids. Certain oral antimalarials (hydroxychloroquine 100-200 mg twice daily and mepacrine 100 mg daily) can prove very useful and are generally safe for long-term intermittent use. Oral prednisolone is beneficial but its use is limited by its side-effect profile. Azathioprine, retinoids, ciclosporin and thalidomide can be useful in resistant cases.
Prognosis
The disease is usually chronic, although it may fluctuate in severity. CDLE remains confined to the skin in most patients and it will eventually go into remission in up to 50% of cases (after many years).
Subacute lupus erythematosus (SCLE)
SCLE is a rare cutaneous variant of LE. It presents with widespread indurated, sometimes urticated, erythematous lesions, often on the upper trunk. The lesions can also be annular. Photosensitivity is often a prominent feature. Complications, such as arthralgia and mouth ulceration, are seen but significant organ involvement is rare. ANF and extractable nuclear antibodies (anti-Ro and anti-La) are usually positive Treatment is with oral dapsone, antimalarials or systemic immunosuppression (prednisolone and ciclosporin).