G Systemic lupus erythematosus
Definition
Systemic lupus erythematosus (SLE) is a chronic inflammatory disorder of connective tissues that affects multiple organ systems with periods of remissions and exacerbations.
Incidence and prevalence
Systemic lupus erythematosus occurs eight to 15 times more often in women than in men and affects approximately 75 in 1,000,000 persons every year. It occurs most often in Asians and in African Americans. Exacerbations are more common in spring and summer and during stresses such as infection, pregnancy, and surgery.
Pathophysiology
The origin of SLE is unknown. One theory is that it is an antibody–antigen autoimmune response. Another theory deals with predisposing factors that promote susceptibility to SLE. These factors include stressors such as infection, exposure to ultraviolet light, immunizations, and pregnancy. A third theory suggests that drugs such as procainamide, hydralazine, penicillin, anticonvulsants, oral contraceptives, and sulfa drugs may trigger SLE.
Clinical manifestations
Clinical manifestations of SLE include arthritis of the upper and lower extremities as well as avascular necrosis of the femur. Systemically, SLE affects major organ systems (heart, lungs, kidneys, liver, neuromuscular system, skin). Pericarditis, myocarditis, tachycardia, arrhythmias, and congestive heart failure may develop. Left ventricular dysfunction and endocarditis have also been associated with SLE. About 50% of patients with SLE develop such cardiopulmonary abnormalities. Pneumonia, pleural effusions, cough, dyspnea, and hypoxemia are common. Glomerulonephritis and oliguric renal failure may result. Some patients develop lupoid hepatitis, which may be fatal. They may also incur intestinal ischemia. The neuromuscular system may be affected by myopathies. Psychological changes include schizophrenia and deterioration of the intellect. The skin may exhibit the typical lesion associated with SLE; this “butterfly rash” appears over the nose and is erythematous. Alopecia may also be seen clinically.