What is Sjögren syndrome?
Sjögren syndrome (SS) is an autoimmune disease that mainly affects secretory glands of the eyes and mouth, stopping them from producing tears and saliva properly (sicca symptoms). SS results in dry eyes (called keratoconjunctivitis sicca), dry mouth (xerostomia) and sometimes arthritis. It develops slowly. When tested, most people with the condition have a positive blood test for anti-Ro antibodies.
Many patients with SS have some features of other autoimmune diseases, such as systemic sclerosis, systemic lupus erythematosus or rheumatoid arthritis. In this case, they are said to have an overlap syndrome or the SS is said to be secondary to the other autoimmune condition. The patient is said to have primary SS if other conditions are not present.
Who gets primary Sjögren syndrome and how often does it develop?
Primary SS is 9 times more common in females than males. It is especially common in older females. However, anyone can develop it. Up to 2% of older females have been found to have primary SS.
What is the cause of Sjögren syndrome?
The cause of SS is not known. One theory is that viruses (such as Epstein-Barr virus) may play a role in triggering SS in people whose genetic background predisposes them to SS. However, once the condition has been triggered there is an infiltrate of lymphocytes into the secretary glands. This is a slow, low-grade inflammatory process that can cause damage to the cells of the glands and thus impairs the function of the glands.
What are the clinical features of Sjögren syndrome?
Eye problems in SS
Patients usually describe dry or gritty eyes. They may also feel a burning discomfort, notice decreased tear production, increased eye fatigue and sometimes intolerance of bright lights (photophobia). These symptoms may develop because of increased dryness of the eyes causing damage to the lining of the cornea at the front of the eyes.
This may develop very gradually over a number of years. When first noticed it may only be the sensation of dryness of the mouth. As it progresses patients may notice difficulty swallowing dry food, difficulty speaking for long lengths of time, problems with dentures and sometimes increased tooth decay. Oral thrush is also more likely to develop.
The most common skin manifestation is dry or rough skin (xerosis), which is noted by more than half of patients. This may result in itch. Patients with SS also sweat less than people without the disease. Although these symptoms are common, most patients with SS are more bothered by the dry mouth and dry eyes. Vaginal dryness may also occur.
Vasculitis (inflammation of blood vessels) is potentially more serious. This develops in about 10% of patients with primary SS and affects the skin in half of them (cutaneous small-vessel vasculitis). Skin lesions usually present as multiple purple or reddish-brown spots. The colour is due to bleeding from small inflamed vessels. Vasculitic skin lesions are most common and prominent on the legs but can develop anywhere. They may present as red flat patches, raised lumps, blisters, ulcers or a raised urticaria-like weals.
Other skin changes that have been reported in Primary SS include:
- Annular erythema (ring-shaped red patches) has been noted in Japanese patients
- Livedo reticularis
- Erythema nodosum
- Diffuse hair loss
- Raynaud phenomenon
Involvement of other organs in Sjögren syndrome
Rarely the gastrointestinal system may be affected in SS. The resulting dryness may inflame the lining of the oesophagus (oesophagitis) and the stomach (atrophic gastritis).
Although SS may affect the lungs and is rarely serious. The most common manifestation is a dry cough, due to dryness of the small airways.
Up to 60% of people with SS will at some stage develop at least one episode of arthralgia (ache in joints) or arthritis (inflammation within the joint). Arthritis does not usually result in erosion of joint structures or in joint deformity.
Involvement of the kidneys is more common if SS is present as part of overlap syndrome with systemic lupus erythematosus. It can affect the kidneys in various ways including interstitial nephritis, kidney stones or glomerulonephritis.
Primary SS vasculitis can damage kidneys, lungs, nerves and joints. Fevers and anaemia may also be present. Involvement of internal organs is more likely if the vasculitis is associated with cryoglobulins (a special form of protein that precipitates at cold temperatures). Some patients with Primary SS and vasculitis have an underlying B-cell lymphoma (cancer of the lymphatic system).
Information Source: DermNet NZ: https://dermnetnz.org/topics/sjoegren-syndrome/