Systemic lupus erythematosus

What is lupus?

Lupus is an autoimmune disease. This means that the immune system, which normally protects us from infections, begins to react against different components of the body itself.

A person is born with a genetic predisposition to develop lupus, but a trigger is generally needed for the disease to appear. Possible triggers include infections, sunlight or ultraviolet exposure, and stress.

Who does it affect?

Lupus is much more common in women.

It often begins during adolescence or in young women. It may appear at other ages, but late onset is less common and requires careful assessment of the diagnosis.

Age, sex and how the disease begins are important epidemiological details. They do not make the diagnosis by themselves, but they form part of the clinical suspicion.

It is a multisystem disease

Lupus does not affect only one joint or one specific part of the body. It is a multisystem disease and can involve different organs.

• The skin.
• The joints.
• The kidneys.
• The lungs.
• The heart.
• The nervous system.

Not everyone has the same manifestations. Some people mainly have skin and joint symptoms, while others may develop kidney, lung, heart or neuropsychiatric involvement.

Skin manifestations

Photosensitivity is a characteristic manifestation. Exposure to sunlight or ultraviolet light may cause or worsen skin lesions and can also trigger disease activity.

One of the best-known lesions is the malar rash, also called a butterfly rash. It appears mainly over the cheekbones and crosses the bridge of the nose.

Lesions may also occur on other sun-exposed areas, such as the upper chest.

Arthritis and overlapping diseases

Lupus can cause arthritis.

In some patients, joint manifestations may be confused with rheumatoid arthritis. A true overlap between both diseases can also exist.

Therefore, not every episode of arthritis in a person with lupus should be assumed to behave in exactly the same way. It is necessary to determine whether it belongs to lupus, another disease or a combination of both.

Kidney and neuropsychiatric involvement

Nephritis is traditionally reported as an important and relatively frequent manifestation of lupus. My clinical experience, however, is different.

In private practice, I diagnose approximately ten episodes of neuropsychiatric activity for every case of nephritis.

This may be explained, at least in part, by how the two manifestations are investigated.

Kidney involvement can be detected relatively easily with a urinalysis, a simple and accessible study that is commonly requested.

Recognizing brain activity, by contrast, may require MRI. This is more complex, more expensive and requested less often. I therefore consider it possible that many neuropsychiatric manifestations of lupus go undiagnosed and are underestimated in some series.

Diagnosis begins with clinical suspicion

Lupus is not diagnosed with one test.

There must first be a clinical suspicion based on symptoms, affected organs and the person's epidemiological characteristics. The appropriate studies are then requested.

One of the first tests is the antinuclear antibody test, known as ANA.

If the result and clinical picture justify it, more specific antibodies are investigated, including:

• Anti-double-stranded DNA antibodies.
• Anti-Smith antibodies.

Results must be interpreted within the medical history. An isolated antibody does not replace assessment of the patient.

Classification criteria do not equal diagnosis

Lists of criteria are often discussed as though they were diagnostic criteria. They are actually classification criteria.

They were developed mainly to classify groups of patients, especially in research. They can help organize information, but they do not replace clinical judgment.

A person may have lupus before meeting every classification criterion. Another person may meet numerous criteria yet have a different disease that better explains the manifestations.

The diagnosis should therefore neither be established nor excluded by mechanically counting a list of criteria.

The lupus band

Among the studies I use is the lupus band test.

A biopsy and special staining may reveal the characteristic deposit, which appears apple green.

I consider the lupus band to have very high sensitivity and specificity when performed and interpreted correctly. It can provide important information when the history, clinical manifestations and other studies suggest lupus.

Treatment must be individualized

There is no single identical treatment for everyone with lupus.

Management depends on:

• Disease activity.
• The presence of a flare.
• The organs involved.
• The severity of each manifestation.

The objective is not simply to treat an abnormal test. We must determine which part of the disease is active, which organ is involved and how severe that activity is.

A person with mainly skin or joint manifestations does not necessarily need the same treatment as someone with kidney, lung, heart or neuropsychiatric involvement.

The goal is to control activity, protect organs and adapt treatment to each patient's particular situation.