Lupus erythematosus
A chronic inflammatory disorder of the connective tissues, lupus erythematosus appears in two forms: discoid lupus erythematosus, which affects only the skin, and systemic lupus erythematosus (SLE), which affects multiple organ systems (as well as the skin) and can be fatal. Like rheumatoid arthritis, SLE is characterized by recurring remissions and exacerbations, which are especially common during spring and summer.
SLE strikes 8 times more women than men, increasing to 15 times among women of childbearing years. It occurs worldwide, but is most prevalent among Asians and blacks. The prognosis improves with early detection and treatment, but remains poor for patients who develop cardiovascular, renal, or neurologic complications or severe bacterial infections.
Gender InfluenceA report by the Centers for Disease Control and Prevention showed a 60% increase in deaths over a 20-year period from SLE. Women were five times more likely to die of complications than men. Nine out of every 10 patients affected with the disease are women, with the highest prevalence in African-Americans, Hispanics, Asians, and Native Americans in the United States. Research on this disorder is ongoing.
Causes
The exact cause of SLE remains a mystery, but available evidence points to interrelated immunologic, environmental, hormonal, and genetic factors.
Immune dysregulation
Immune dysregulation, in the form of autoimmunity, is thought to be the prime causative mechanism. With autoimmunity, the body produces antibodies against components of its own cells, such as the antinuclear antibody (ANA). The formed antigen-antibody complexes can activate the body’s immunity and damage tissues. One significant feature in patients with SLE is their ability to produce antibodies against many different tissue components, such as red blood cells, neutrophils, platelets, lymphocytes, or almost any organ or tissue in the body.
Signs and symptoms of systemic lupus erythematosus
Diagnosing systemic lupus erythematosus (SLE) is difficult because it commonly mimics other diseases, with the signs and symptoms often vague and varying greatly from patient to patient.
For these reasons, the American Rheumatism Association has issued a list of criteria for classifying SLE, to be used primarily for consistency in epidemiologic surveys. Usually, four or more of these signs are present at some time during the course of the disease:
malar or discoid rash
photosensitivity
oral or nasopharyngeal ulcerations
nonerosive arthritis (of two or more peripheral joints)
pleuritis or pericarditis
profuse proteinuria (exceeding 0.5 g/day) or excessive cellular casts in the urine
seizures or psychoses
hemolytic anemia, leukopenia, lymphopenia, or thrombocytopenia
anti-double-stranded deoxyribonucleic acid (dsDNA) or antiSmith antibody test or positive findings of antiphospholipid antibodies (elevated immunoglobulin [Ig] G or IgM anticardiolipin antibodies, positive test for lupus anticoagulant, or false-positive serologic tests for syphilis)
abnormal antinuclear antibody titer.
Predisposing factors
Physical or mental stress, streptococcal or viral infections, exposure to sunlight or ultraviolet light, immunization, pregnancy, and abnormal estrogen metabolism may all affect the development of this disease in a genetically susceptible individual.
SLE also may be triggered or aggravated by treatment with certain drugs—for example, procainamide, hydralazine, anticonvulsants and, less commonly, penicillins, sulfa drugs, and hormonal contraceptives.
Signs and symptoms
The onset of SLE may be acute or insidious and produces no characteristic clinical pattern. However, signs and symptoms commonly include fever, weight loss, malaise, fatigue, rashes, and polyarthralgia. SLE may involve any organ system. (See Signs and symptoms of systemic lupus erythematosus.)
Joint and skin effects
In 90% of patients, joint involvement is similar to that in rheumatoid arthritis (although the arthritis of lupus is usually nonerosive). Most skin lesions are in the form of an erythematous rash in areas exposed to light. The classic butterfly rash over the nose and cheeks occurs in fewer than 50% of the patients. A scaly papular rash (which mimics psoriasis) may also develop, especially in sun-exposed areas. Ultraviolet rays often provoke or aggravate skin eruptions. (See Discoid lupus erythematosus, page 502.) Vasculitis can develop (especially in the digits), possibly leading to infarctive lesions, necrotic leg ulcers, or digital gangrene. Raynaud’s phenomenon appears in about 20% of patients. Patchy alopecia and painless ulcers of the mucous membranes are common.
Cardiopulmonary effects
About 50% of patients with SLE develop signs of pulmonary abnormalities, such as pleurisy, pleural effusions, pneumonitis, pulmonary hypertension and, rarely, pulmonary hemorrhage. Cardiac involvement may include pericardial effusion, pericarditis, myocarditis,
endocarditis, and early coronary atherosclerosis.
endocarditis, and early coronary atherosclerosis.
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