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|Lupus erythematosus |
Classification and external resources
|Typical "butterfly"-like rash over the cheeks in lupus. (Artist's interpretation.)|
Systemic lupus erythematosus (SLE or lupus, pronounced sɪˈstɛmɪk ˈluːpəs ˌɛrəˌθiməˈtoʊsəs (help·info)) is a chronic autoimmune connective tissue disease that can affect any part of the body. As occurs in other autoimmune diseases, the immune system attacks the body’s cells and tissue, resulting in inflammation and tissue damage.
SLE most often harms the heart, joints, skin, lungs, blood vessels, liver, kidneys, and nervous system. The course of the disease is unpredictable, with periods of illness (called flares) alternating with remissions. The disease occurs nine times more often in women than in men, especially between the ages of 15 and 50, and is more common in those of non-European descent.
SLE is treatable through addressing its symptoms, mainly with corticosteroids and immunosuppressants; there is currently no cure. SLE can be fatal, although with recent medical advances, fatalities are becoming increasingly rare. Survival for people with SLE in the United States, Canada, and Europe is approximately 95% at five years, 90% at 10 years, and 78% at 20 years.
- Chronic cutaneous lupus erythematosus
- Discoid lupus erythematosus, a skin disorder that causes a red, raised rash on the face and scalp. Discoid lupus occasionally (1–5%) develops into SLE.
- Chilblain lupus erythematosus (Hutchinson)
- Lupus erythematosus-lichen planus overlap syndrome
- Lupus erythematosus panniculitis (Lupus erythematosus profundus)
- Subacute cutaneous lupus erythematosus, which causes nonscarring skin lesions on patches of skin exposed to sunlight.
- Tumid lupus erythematosus
- Verrucous lupus erythematosus (Hypertrophic lupus erythematosus)
- Neonatal lupus erythematosus, a rare disease affecting babies born to women with SLE, Sjögren's syndrome, or sometimes no autoimmune disorder. It is theorized that maternal antibodies attack the fetus, causing skin rash; liver problems; low blood counts, which gradually fade; and heart block, leading to bradycardia.
- Childhood systemic lupus erythematosus, the pediatric variant of systemic lupus erythematosus.
- Drug-induced lupus erythematosus, a drug-induced form of SLE; this type of lupus can occur equally in either sex.
- Lupus nephritis, an inflammation of the kidneys caused by SLE.
- Complement deficiency syndromes
 Signs and symptoms
SLE is one of several diseases known as "the great imitators" because it often mimics or is mistaken for other illnesses. SLE is a classical item in differential diagnosis, because SLE symptoms vary widely and come and go unpredictably. Diagnosis can thus be elusive, with some people suffering unexplained symptoms of untreated SLE for years.
Common initial and chronic complaints are fever, malaise, joint pains, myalgias, fatigue, and temporary loss of cognitive abilities. Because they are so often seen with other diseases, these signs and symptoms are not part of the diagnostic criteria for SLE. When occurring in conjunction with other signs and symptoms (see below), however, they are considered suggestive.
- Dermatological manifestations
As many as 30% of sufferers have some dermatological symptoms (and 65% suffer such symptoms at some point), with 30% to 50% suffering from the classic malar rash (or butterfly rash) associated with the disease. Some may exhibit thick, red scaly patches on the skin (referred to as discoid lupus). Alopecia; mouth, nasal, and vaginal ulcers; and lesions on the skin are also possible manifestations.
- Musculoskeletal manifestations
The most commonly sought medical attention is for joint pain, with the small joints of the hand and wrist usually affected, although all joints are at risk. The Lupus Foundation of America estimates that more than 90 percent will experience joint and/or muscle pain at some time during the course of their illness. Unlike rheumatoid arthritis, lupus arthritis is less disabling and usually does not cause severe destruction of the joints. Fewer than ten percent of people with lupus arthritis will develop deformities of the hands and feet. SLE patients are at particular risk of developing osteoarticular tuberculosis.
It is suggested that there might be an association between rheumatoid arthritis and SLE. and that it is associated with high prevalence of vertebral fractures in the relatively young patients.
- Hematological manifestations
Anemia and iron deficiency may develop in up to 50% of cases. Low platelet and white blood cell counts may be due to the disease or a side-effect of pharmacological treatment. People with SLE may have an association with antiphospholipid antibody syndrome (a thrombotic disorder), wherein autoantibodies to phospholipids are present in their serum. Abnormalities associated with antiphospholipid antibody syndrome include a paradoxical prolonged PTT (which usually occurs in hemorrhagic disorders) and a positive test for antiphospholipid antibodies; the combination of such findings have earned the term lupus anticoagulant-positive. Another autoantibody finding in SLE is the anticardiolipin antibody, which can cause a false positive test for syphilis.
- Cardiac manifestations
A person with SLE may have inflammation of various parts of the heart, such as pericarditis, myocarditis, and endocarditis. The endocarditis of SLE is characteristically noninfective (Libman-Sacks endocarditis) and involves either the mitral valve or the tricuspid valve. Atherosclerosis also tends to occur more often and advances more rapidly than in the general population.
- Pulmonary manifestations
Lung and pleura inflammation can cause pleuritis, pleural effusion, lupus pneumonitis, chronic diffuse interstitial lung disease, pulmonary hypertension, pulmonary emboli, pulmonary hemorrhage, and shrinking lung syndrome.
- Renal involvement
Painless hematuria or proteinuria may often be the only presenting renal symptom. Acute or chronic renal impairment may develop with lupus nephritis, leading to acute or end-stage renal failure. Because of early recognition and management of SLE, end-stage renal failure occurs in less than 5% of cases.
A histological hallmark of SLE is membranous glomerulonephritis with "wire loop" abnormalities. This finding is due to immune complex deposition along the glomerular basement membrane, leading to a typical granular appearance in immunofluorescence testing.
- Neuropsychiatric manifestations
Neuropsychiatric syndromes can result when SLE affects the central or peripheral nervous system. The American College of Rheumatology defines 19 neuropsychiatric syndromes in systemic lupus erythematosus. The most common neuropsychiatric disorder people with SLE have is headache, although the existence of a specific lupus headache and the optimal approach to headache in SLE cases remains controversial. Other common neuropsychiatric manifestation of SLE include cognitive dysfunction, mood disorder, cerebrovascular disease, seizures, polyneuropathy, anxiety disorder, and psychosis. It can rarely present with intracranial hypertension syndrome, characterized by an elevated intracranial pressure, papilledema, and headache with occasional abducens nerve paresis, absence of a space-occupying lesion or ventricular enlargement, and normal cerebrospinal fluid chemical and hematological constituents.
More rare manifestations are acute confusional state, Guillain-Barré syndrome, aseptic meningitis, autonomic disorder, demyelinating syndrome, mononeuropathy (which might manifest as mononeuritis multiplex), movement disorder (more specifically, chorea), myasthenia gravis, myelopathy, cranial neuropathy and plexopathy.
- Systemic manifestations
Fatigue in SLE is probably multifactorial and has been related not only to disease activity or complications such as anemia or hypothyroidism but also to pain, depression, poor sleep quality, poor physical fitness and perceived lack of social support.
- Other rarer manifestations
Lupus gastroenteritis, menstrual disturbances, lupus pancreatitis, lupus cystitis, autoimmune inner ear disease, parasympathetic dysfunction, retinal vasculitis, hemophagocytic syndrome, systemic vasculitis, and like many autoimmune diseases can be complicated by myeloid malignancies.
The first mechanism may arise genetically. Research indicates that SLE may have a genetic link. SLE does run in families, but no single, causal, gene has been identified. Instead, multiple genes appear to influence a person's chance of developing lupus when triggered by environmental factors. The most important genes are located in the HLA region on chromosome 6, where mutations may occur randomly (de novo) or may be inherited. HLA class I, class II, and class III are associated with SLE, but only class I and class II contribute independently to increased risk of SLE. Other genes which contain risk variants for SLE are IRF5, PTPN22, STAT4, CDKN1A, ITGAM, BLK, TNFSF4 and BANK1. some of the susceptibility genes may be population specific.
 Environmental triggers
The second mechanism may be due to environmental factors. These factors may not only exacerbate existing SLE conditions but also trigger the initial onset. They include certain medications (such as some antidepressants and antibiotics), extreme stress, exposure to sunlight, hormones, and infections. UV radiation has been shown to trigger the photosensitive lupus rash and some evidence suggests that UV light might be capable of altering the structure of the DNA, leading to the creation of autoantibodies. Sex hormones such as estrogen play an important role in the occurrence of SLE and it is observed that during reproductive years, the frequency of SLE is 10 times greater in females than in males. Researchers have sought to find a connection between certain infectious agents (viruses and bacteria), but no pathogen can be consistently linked to the disease. Some researchers have found that women with silicone gel-filled breast implants have produced antibodies to their own collagen, but it is not known how often these antibodies occur in the general population, and there are no data that show that these antibodies cause connective tissue diseases such as SLE. There is also a small but growing body of evidence linking SLE to lipstick usage, although lipstick manufacturers do not appear to be concerned about it.
 Drug reactions
Drug-induced lupus erythematosus is a (generally) reversible condition that usually occurs in people being treated for a long-term illness. Drug-induced lupus mimics SLE. However, symptoms of drug-induced lupus generally disappear once the medication that triggered the episode is stopped. There are about 400 medications that can cause this condition, the most common of which are procainamide, hydralazine, quinidine, and phenytoin.
 Non-SLE forms of lupus
Other forms of lupus can predispose to SLE. About 1–5% of cases of discoid lupus eventually develop into SLE. Discoid (cutaneous) lupus is limited to skin symptoms and is diagnosed by biopsy of skin rash on the face, neck, or scalp. Often an antinuclear antibody (ANA) test for discoid lupus is negative or a low-titer positive.