Systemic lupus erythematosus in Adult
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Synopsis
The etiology of SLE is poorly understood, but there is a strong association with autoantibodies and SLE. For example, even though the autoantibodies are not organ specific, only certain organs in a given patient demonstrate end-organ damage. It is hypothesized that a complex interplay between genetic proclivity and environmental influences leads to a perpetuated autoimmune response. Autoantibodies play significant roles in the diagnosis, management, and prognosis of SLE. They are as follows:
- Anti-dsDNA – Highly specific for SLE. Rising levels correlate with increased SLE activity and an increased risk for SLE nephritis. Seen in approximately 55%-65% of SLE patients.
- Anti-Sm – Highly specific for SLE. Seen in approximately 25%-30% of SLE patients. Considerable diagnostic value, but levels do not correlate with disease activity.
- Anti-RNP – Highly specific for SLE. Seen in approximately 5% of SLE patients.
- Antinuclear antibody (ANA) – Highly sensitive for SLE. Seen in approximately 99% of SLE patients. In other words, it is very rare for an individual with SLE to have a negative ANA. Considerable screening value, but levels do not correlate with disease activity.
- Anti-histones – Highly specific for drug-induced SLE.
The organ systems most commonly affected in SLE are the joints, skin, renal, pulmonary, central nervous system (including ischemic stroke), cardiovascular, and hematologic. Patients may be anemic.
Arthritis is classically migratory, polyarticular, and symmetrical and a common early finding. Skin and mucous membrane abnormalities are also common with the classic "butterfly" malar rash (involving the cheeks and nose) developing after sun exposure. About half of SLE patients will have significant renal involvement that can take the form of several types of glomerulonephritis. Renal biopsy is useful to define the type and extent of involvement. Other complications include thromboembolic disease, particularly in the setting of antiphospholipid antibodies, vasculitis, and gastrointestinal (GI), pulmonary, and cardiac involvement.
Of note, SLE patients often require a multidisciplinary team and, hence, efforts should be made to clarify the level and location of involvement to assist the various disciplines.
SLE is a chronic disease with no known cure. However, there are several disease-modifying medications that are effective in decreasing the burden of disease. The mortality from SLE has decreased in the last several decades. Certain patient characteristics portend a worse prognosis in SLE: male sex, age (both young and old), low socioeconomic status, and black race. Disease phenotypes associated with a poor prognosis include hypertension, renal involvement, antiphospholipid antibody positivity, and antiphospholipid antibody syndrome.
Related topics: Neonatal lupus erythematosus, Discoid lupus erythematosus, Drug-induced lupus erythematosus, Oral lupus erythematosus, Subacute cutaneous lupus erythematosus, Tumid lupus erythematosus
Codes
ICD10CM:M32.9 – Systemic lupus erythematosus, unspecified
SNOMEDCT:
55464009 – Systemic lupus erythematosus
Look For
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Diagnostic Pearls
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Differential Diagnosis & Pitfalls
- Rheumatoid arthritis
- Mixed connective tissue disease – Check for anti-U1RNP antibody. Most patients are positive for this in mixed connective tissue disease.
- Scleroderma – Check for anticentromere antibodies and anti-Scl-70 antibodies. Typified by sclerotic changes in skin not seen in dermatomyositis.
- Systemic sclerosis
- Drug-induced SLE
- Dermatomyositis – Characteristic heliotrope rash (violaceous plaques surrounding eyes), photodistributed cutaneous eruption, and nail fold changes. Look for elevated serum creatinine kinase (CK) levels and proximal symmetric extremity weakness.
- Rosacea – ANA negative.
- Stevens-Johnson syndrome – Characteristic target lesions, prominent systemic symptoms, but ANA and direct immunofluorescence test (DIF) negative.
- Antiphospholipid antibody syndrome / lupus anticoagulant – Can overlap with SLE; associated with recurrent thromboses and spontaneous abortions, elevated prothrombin time (PT).
- Polymorphous light eruption (PMLE) – Most lesions resolve within several days; skin lesions are located primarily on sun-exposed areas (SLE can occur on sun-exposed and sun-protected areas). Note that previous studies have shown that up to 19% of patients with PMLE can be ANA positive. Hence, an ANA alone may not be sufficient in differentiating PMLE from SLE.
- Phototoxic / photoallergic drug eruptions
- CREST syndrome – Can have overlap with dermatomyositis. Refers to a subset of patients with limited scleroderma.
- Seborrheic dermatitis – No systemic findings. Erythema and scale in sebaceous distribution.
- Systemic amyloidosis
- Contact dermatitis
- Pityriasis rubra pilaris
- Sarcoidosis
- Graft-versus-host disease – Occurs after allogeneic stem-cell transplantation.
- Generalized morphea – Asymmetric induration, no Raynaud phenomenon, no systemic involvement.
- Polymyositis – Without cutaneous findings.
- Acute lesions of erythropoietic protoporphyria may have similar locations, especially on the dorsum of the hands, but usually there is no weakness.
- Tinea faciei – Check potassium hydroxide (KOH); will also be ANA negative.
- Chilblains (perniosis)
- Methotrexate-induced mucocutaneous toxicity
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References
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Last Reviewed:02/08/2019
Last Updated:12/03/2019
Last Updated:12/03/2019
Systemic lupus erythematosus in Adult
See also in: Nail and Distal Digit