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SKIN DISEASE IN LUPUS

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Thomas T. Provost, M.D. Noxell Professor and Chairman Department of Dermatology The Johns Hopkins School of Medicine, Baltimore, MD
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Voir également : Le lupus érythémateux disséminé

Skin disease is very common in lupus erythematosus. It ranks second only to arthritis in frequency of occurrence. Approximately 20% of people with systemic lupus erythematosus (SLE) will have ring-shaped or coin-shaped, scarring lesions as the initial symptom of their disease. In addition, it has been estimated that as many as 60-65% of people with SLE will develop skin rashes or lesions at some time during the course of their illness. However, with the use of oral steroids (Prednisone), and anti-malarial drugs (hydroxychloroquine, or Plaquenil), the occurrence of these skin lesions is now less frequent. The skin rashes and lesions of lupus erythematosus can be divided into those that are specific to lupus and those that can occur in other diseases as well as lupus (non-specific lesions). There are two specific lesions associated with lupus erythematosus: discoid lesions (characteristic of discoid lupus erythematosus), and coin-shaped, non-scarring lesions (characteristic of subacute cutaneous lupus erythematosus).

Discoid Lesions

The term discoid is a very confusing term which, unfortunately, is inappropriately used by many people, including physicians. The term discoid simply means coin-shaped. The scarring coin-shaped lupus lesion commonly seen on areas of the skin that are exposed to light has been termed discoid lupus erythematosus. This term refers only to the description of the lupus lesion on the skin and should not be employed to distinguish cutaneous lupus from systemic lupus erythematosus. A physician cannot determine whether or not a discoid lupus lesion on the skin is occurring in the presence or absence of systemic features just by examining the shape of the lesion. This can only be done by taking a complete history and physical examination and interpreting the results of appropriate blood tests.

What is the relationship between discoid and systemic lupus erythematosus? This is a common question. Lupus erythematosus should be viewed as a continuum of a spectrum of the disease. At one end of the spectrum, in its most mild form, it is characterized by coin-shaped, scarring, skin lesions which we term discoid lesions. At the other end of the spectrum are those systemic lupus erythematosus patients who have no skin lesions, but have systemic features (i.e., arthritis or renal disease). People with only discoid lesions and no systemic features commonly have no auto-antibodies in their serum (i.e., antinuclear or anti-DNA tests will be negative). On the other hand, people with systemic lupus erythematosus are characterized by the presence of one or more types of auto-antibodies in their blood. From personal experience and from reviewing the literature, it has been estimated that between 5 and 10% of patients initially presenting with only the coin-shaped lesions of discoid lupus will, with time, develop systemic features. As noted above, approximately 20% of people with systemic lupus erythematosus will at the time of the initial presentation of their disease have discoid lupus lesions. These data indicate that, at times, the lupus disease process is dynamic and, with time, a small percentage of those patients who only have discoid lupus lesions will eventually develop systemic disease. In addition to these coin-shaped, scarring lesions, there are several different types of discoid lupus lesions with which patients should be familiar. Occasionally, the discoid lupus lesions may occur in the scalp producing a scarring, localized baldness termed alopecia. At times, these discoid lesions may appear over the central portion of the face and nose producing a characteristic butterfly rash.

This type of lupus obviously has significant cosmetic implications. The discoid lupus lesions may develop thick, scaly (hyperkeratotic) formations and are termed hyperkeratotic or hypertrophic cutaneous lupus lesions. Discoid lupus lesions may also occur in the presence of thickening (deep induration) of the layers of underlying skin. This is termed lupus profundus.

At the present time, research indicates that discoid lupus lesions are the result of an inflammatory process in the skin in which the patients' lymphocytes (predominantly T-cells) play a major role. This is in contrast to systemic lupus erythematosus, where autoantibodies and immune complex formation are responsible for many of the clinical symptoms.

Treatment

The treatment of skin disease in lupus erythematosus involves the use of a number of drugs as well as the use of sunscreens. Individual lupus lesions can be treated with the topical application of steroid creams, the application of a steroid impregnated tape to cover the lupus lesion, or the intralesional injection of low doses of steroid. Widespread lupus lesions are frequently treated using hydroxychloroquine (Plaquenil) alone, or in combination with, a short burst of oral steroids. On very unusual occasions, unmanageable, cosmetically objectionable lupus lesions have been successfully treated with vitamin A derivatives (such as Tegison). Sun protection can do a lot to prevent the development of lupus skin lesions. People with lupus should avoid prolonged periods of exposure to sunlight, especially between the hours of 10 am and 3 pm, when the sun is at its brightest. It is also a good idea to wear a wide-brimmed hat and avoid clothing made of thin fabric which will admit sunlight. In addition, the regular use of sunscreens with a sun protective factor rating of SPF 15 will also provide protection. In recent years, research has shown that ultraviolet light of long wavelengths, as well as ultraviolet light in the sunburn spectrum, is capable of producing lupus skin lesions. Sunscreens capable of blocking this long wave ultraviolet light are now available. In contrast to ordinary sunscreens which generally contain paraminobenzoic acid (PABA) esters and benzophones, these sunscreens are actually sunblocks and contain titanium oxide. For specific information regarding the treatment of various skin manifestations of lupus erythematosus, as well as the employment of sunscreens, consult your dermatologist, or your local chapter of the Lupus Foundation of America.
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