83. Systemic Lupus Erythematosus
Definition
Systemic lupus erythematosus (SLE) is a chronic, generalized, multifaceted inflammatory disorder that can affect every organ. SLE is categorized as an autoimmune disease characterized by autoantibody formation, producing multisystem microvascular inflammation.
Incidence
In the United States the average incidence of SLE is about 1:10,000. The incidence varies with ethnicity. The female:male ratio ranges from 8:1 to 10:1. Internationally the incidence is variable by country and ethnicity (see the table below).
Etiology
The specific cause of SLE has not yet been elucidated. There are suspected causes, including immune system dysregulation as well as immune complex tissue damage—particularly in the skin and kidneys. Development of SLE may result from multiple immune disturbances. In addition, 10 gene loci have been implicated in increased risk of development of SLE.
American College of Rheumatology Systemic Lupus Erythematosus Diagnosis Criteria
This is called the SOAP BRAIN MD mnemonic:
| Serositosis | Pleurisy, pericarditis |
| Oral ulcers | Oral or nasopharyngeal, usually painless; the palate is most specific |
| Arthritis | Nonerosive, Jaccoud-type |
| Photosensitivity | Unusual skin reaction to light exposure |
| Blood disorders | Leukopenia, lymphopenia, thrombocytopenia, positive result of Coombs-test for anemia |
| Renal involvement | Proteinuria (>0.5 g/day) |
| Antinuclear antibodies (ANAs) | Higher titers generally more specific (>1:160) |
| Immunologic phenomena | Lupus erythematosus (LE) cells; anti–double-stranded DNA (dsDNA); anti-Smith (Sm) antibodies; antiphospholipid antibodies; lupus; anticoagulants |
| Neurologic disorder | Seizures or psychosis |
| Malar rash | Fixed erythema over the cheeks and nasal bridge |
| Discoid rash | Raised rimmed lesions that have keratotic scaling and follicular plugging |
Signs and Symptoms
• Alopecia
• Anasarca
• Aseptic meningitis
• Bullous lesions
• Crackles
• Diffuse intrapulmonary hemorrhage
• Dysrhythmias
• Effusions
• Fever
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