Systemic Lupus Erythematosus
What is Systemic Lupus Erythematosus
Systemic lupus erythematosus (SLE) remains the classic example of a systemic autoimmune disease, given its capacity to encompass every organ system. The term "lupus," Latin for wolf, was initially used because facial lesions were thought to resemble animal bites. Kaposi recognized that cutaneous lupus could be associated with systemic disease including fever, neurologic symptoms, pleuropneumonia, and anemia. The breadth of systemic manifestations, including arthritis, pneumonia, central nervous system (CNS) disease, gastrointestinal crises, endocarditis, pericarditis, nephritis, and hemorrhage was described by Osler. Osler also described the natural history of recurrent exacerbations, or flares. Important clinical descriptions of lupus were compiled by Ropes and the Hopkins group.
CLASSIFICATION OF LUPUS
Systemic Lupus Erythematosus is one of several forms of lupus
). Other forms include chronic cutaneous (discoid) lupus (without other systemic features), drug-induced lupus (a self-limited form of lupus, predominantly arthritis and serositis, which resolves when the offending drug is discontinued), subacute cutaneous lupus, and neonatal lupus (a transient rash or permanent congenital heart block in a newborn exposed by placental transfer of maternal anti-Ro). Patients with some features of SLE that are not sufficient enough to warrant a diagnosis of SLE are usually diagnosed with undifferentiated connective tissue disease (UCTD).
Types of lupus erythematosus
|Systemic lupus erythematosus (SLE)
|Chronic cutaneous (discoid) lupus (CLE)
|Subacute cutaneous lupus erythematosus (SCLE)
|Drug-induced lupus erythematosus (DILE)
|Neonatal lupus erythematosus (NLE)
Subacute cutaneous lupus erythematosus (SCLE) can occur in patients with SLE, although it is quite rare (5%). Patients labeled with SCLE alone, without SLE, may have serologic or laboratory features suggestive of SLE, but do not meet classification criteria for SLE.
EPIDEMIOLOGY and Causes of Systemic Lupus Erythematosus
One of the most striking features of SLE is its female predominance. The importance of female hormones in the pathogenesis of SLE has been elegantly studied in murine models.
Age at Onset -
Systemic Lupus Erythematosus is usually a postpubertal disease, with onset of clinical symptoms usually in the 20s to 30s. Childhood and older-onset SLEs differ from the classic presentation, with less female predominance and different clinical presentations. In the HLC, younger-onset SLE (before age 20) has an increase in cutaneous and renal SLE and is more likely have low serum C4 than older-onset SLE.
Race affects both the presentation and the course of SLE. Blacks with SLE are more likely than whites to have discoid SLE
), lymphadenopathy, myositis, and pericarditis, but less likely to have malar rash and mouth ulcers.
Socioeconomic Factors -
Differences in Systemic Lupus Erythematosus presentation and course that are ascribed to socioeconomic status may actually be due to other factors. In a prospective study of predictors of poor renal outcome (renal insufficiency, renal failure, and chronic nephrotic syndrome), socioeconomic status and race were not found to be significant predictors. Instead, compliance (with visits and medication) and hypertension were the major explanatory variables for poor renal outcomes
CLINICAL MANIFESTATIONS OF SLE - Initial Versus Cumulative Symptoms/Signs of SLE
The most common initial symptoms/signs of Systemic Lupus Erythematosus are cutaneous, musculoskeletal, renal, and hematologic. Because of lupus "spread" to other organ systems over time, cumulative frequencies are higher than initial ones.