What causes Scleroderma?
It is difficult to say precisely what triggers this autoimmune disease.
Some contributing factors have been identified
(ref. Dr. France Joyal, About scleroderma in Quebec)
1) Genetic predisposition:
It is very rare to find another case of scleroderma within the same family. However, some family members may have Raynaud’s phenomenon or suffer from a collagenosis or a connective tissue disease. Rhumatoid arthritis, lupus erythematosus, mixed connective tissue disease, Sjögren’s syndrome and scleroderma all belong to the collagenosis group. There is for these families a genetic predisposition or susceptibility to the presence of those diseases.
2) Abnormal immune activity:
The activation of a group of cells, called fibroblasts, results in collagen deposits associated with a surrounding inflammatory reaction (our immune response) that transforms into fibrosis. This transformation, which is abnormal because it is directed against our own cells, may vary from organ to organ and person to a person. It is unclear whether this transformation is the result of damage to small vessels that supply blood to the organs of our body or if it is the blood vessels’ disease which subsequently induced a fibrosis reaction around the affected organs; these two damage mechanisms are not necessarily at work in the same organ. Is the activation related to a virus, a chemical substance or a physical attack? Environment may contribute to triggering a cascade reaction resulting in scleroderma; however, currently, we do not know the cause for the majority of SSc patients.
Autoimmune reaction primarily affects three types of cells:
- Fibroblasts whose activity is increased resulting in excessive collagen production in the skin and internal organs;
- Endothelial cells of small blood vessels called capillaries whose obliteration leads to progressive ischemia and dysfunction of affected organs.
- Lymphocytes, which by producing disease-specific autoantibodies contribute to the development and complications of SSc.
The diagnosis of SSc is primarily based on clinical examination. In the absence of skin fibrosis, the diagnosis can be long to make since the first symptoms that prompt a person to seek medical attention are usually common problems, such as Raynaud’s phenomenon or gastro-esophageal reflux.
Raynaud’s phenomenon, which is indicative of arterial microvascular abnormalities, is the first clinical sign and precedes by several years the occurrence of other manifestations. It is recommended that anyone having this symptom be referred to a medical specialist who will make an assessment using a variety of tests, e.g. a nailfold capillaroscopy, blood work and a skin biopsy.
Nailfold capillaroscopy consists in examining the fingertips using a microscope. It can reveal typical abnormal dilation of the capillaries. As for the blood work, it reflects the functioning of organs and the presence of SSc-specific autoantibodies. These tests help diagnose or identify people with a high probability of suffering from this disease (Koenig, 2008).
A skin biopsy can also confirm the diagnosis by revealing, among other things, abnormal collagen deposits and thickening of the blood vessel walls.
Once the diagnosis of scleroderma is clearly established, further tests will help determine the degree of internal organ involvement. These include a chest scan, pulmonary function tests, an electrocardiogram, an echocardiogram, a radiograph of the hands and an esophago-gastro-duodenoscopy (ogd). More specifically, an esophageal manometry test or a barium swallow will assess the motility of the esophagus.