Lupus

Alternative names

Disseminated lupus erythematosus; SLE; Systemic lupus erythematosus; Lupus erythematosus

Definition

Systemic lupus erythematosus (SLE) is a chronic, inflammatory autoimmune disorder. It may affect many organ systems including the skin, joints, and internal organs.

Causes, incidence, and risk factors

Normally, the immune system controls the body's defenses against infection. In SLE and other autoimmune diseases, these defenses are turned against the body and rogue immune cells attack tissues. Antibodies may be produced that can react against the body's blood cells, organs, and tissues. These lead immune cells to attack the affected systems, producing a chronic (long-term) disease.

The mechanism or cause of autoimmune diseases is not fully known, but many researchers suspect it occurs following infection with an organism that looks similar to particular proteins in the body, which are later mistaken for the organism and wrongly targeted for attack.

The disease affects 9 times as many women as men. It may occur at any age, but appears most often in people between the ages of 10 and 50 years. SLE may also be caused by certain drugs. When this occurs, it is known as drug-induced lupus erythematosus and it is usually reversible when the medication is stopped.

The course of the disease may vary from a mild episodic illness to a severe fatal disease. Symptoms also vary widely in a particular individual over time and are characterized by periods of remission and exacerbation. At its onset, only one organ system may be involved. Additional organs may become involved later. The following organ system manifestations may be seen, but other manifestations are possible.

MUSCLES AND BONES

Almost all people with SLE have joint pain and most develop arthritis. Frequently affected joints are the fingers, hands, wrists, and knees. Death of bone tissue can occur in the hips and shoulders and is frequently a cause of pain in those areas.

SKIN

A "butterfly" rash over the cheeks and bridge of the nose affects about half of those with SLE. The rash is usually worsened by sunlight. A more diffuse rash may appear on other body parts that are exposed to the sun. Other skin lesions or nodules can also occur.

KIDNEYS

Some people with SLE have deposits of antibodies within the cells (glomeruli) of the kidneys. However, less than 50% have lupus nephritis as defined by persistent inflammation (irritation and swelling) in the kidney. These patients may eventually develop kidney failure and require dialysis or kidney transplantation.