SCLERODERMA: PATHOGENESIS, CLINICAL FEATURES AND TREATMENT
Author: Sanketh DS, MDS
Scleroderma is a generalised condition characterised by excessive deposition of collagen in the skin and multiple internal organs, alterations in the vasculature and immunologic abnormalities. The pathogenesis is unclear and is still only a hypothesis.
It is hypothesised that, an unknown etiological agent may trigger the disease in a genetically predisposed individual, which may lead to molecular and cellular alterations.
Etiological agents could be viruses (Cytomegalo virus, Retro virus), chemicals (silica, organic solvents), presence of HLA-B8, DR5, DR3 and DR52, unknown agent through a materno-fetal transfer or a phenotypic change in the cells. The cells altered are the fibroblasts, endothelial cells and the immune cells. Altered fibroblasts produce excessive collagen in the skin and multiple organs, altered endothelial cells may cause obliteration of arteries and arterioles and altered immune cells may have a dysregulated production of cytokines and abnormal production of auto-antibodies. These auto-antibodies may combine with self-antigens, forming immune complexes and along with cytokines may further damage blood vessels and induce fibroblasts to produce collagen.
This condition presents mostly in adults of age 30-50 and has a female predilection of 3-6:1. Scleroderma usually begins with symptoms on the skin of the face, hands and trunk.
One of the first signs of the disease, although not specific for scleroderma, is the Raynaud’s phenomenon. In Raynaud’s phenomenon, there is narrowing or vasoconstriction of the small arteries supplying the skin of the extremities. When the affected person is exposed to cold temperatures or has an emotional distress, there is a vasospasm and lesser blood supply to the extremities leading to the skin becoming pale yellow or white and cold and numb.
The skin develops a hard texture, cannot be wrinkled or picked up, because it becomes indurated or fixed to the underlying connective tissue. When the skin of the face is involved, the face becomes taut, expressionless and is mask-like. Fibrosis of fingers may cause tightness and stiffness of skin on the digits leading to claw like fingers. There may be ulceration under the finger tips, due to vascular obliteration and ischemia.
Other organs may slowly get involved with fibrosis manifesting in the kidneys, lungs and the gastrointestinal tract. Progressive fibrosis, may lead to organ failure.
A milder form of systemic sclerosis is called localised scleroderma or morphea. There may be one or many, well defined areas of elevated linear patches on the skin of the face, and trunk which may look like scars. They are hence called, coup de sabre which means “strike of a sword” since they look like scars due to a blow of a sword! This localised condition is however, not life threatening unlike its systemic counterpart.
Peri-oral tissues become hard as a result of collagen deposition and this may result in microstomia, limitation of the opening of the mouth. Furrows radiate from the mouth to produce a “purse-string” appearance. Intra-orally, the tongue becomes stiff, hypomobile and board like, leading to difficulty in eating and speaking. Also, the oesophagus looses elasticity and becomes firm, leading to difficulty in swallowing. Multiple areas of gingival recession are found and the patient also develops xerostomia due to fibrosis of salivary glands.
Dental radiographs may reveal a diffuse widening of the periodontal ligament space. This has been confirmed by many studies, and is in fact enough to establish a tentative diagnosis of scleroderma, although prudence is to be practised as there are other conditions like osteosarcoma and periodontal disease which may have this feature. 10-20 % of the patients may show, resorption of the posterior ramus, coronoid process and condyle.
The primary feature under the microscope, is the vast and diffuse deposition of collagen in the stroma of the organ involved.
Unfortunately, there is no specific satisfactory treatment for scleroderma. Sometimes, the disease may stabilize on its own or patients may succumb to multiple organ failure due to fibrosis. Drugs like pencillamine have been administered to reduce collage deposition and cortico-steroids are of little benefit. Most of the management strategies have been to give symptomatic relief. Overall, the prognosis for the systemic condition is poor, although it is better for patients with the localised cutaneous form.
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