Scleroderma is an autoimmune disease of the connective tissue.
Scleroderma is a rare, chronic disease characterized by excessive deposits of collagen in the skin or other organs. The localized type of the disease, while disabling, tends not to be fatal. Diffuse scleroderma or systemic sclerosis, the generalized type of the disease, can be fatal as a result of heart, kidney, lung or intestinal damage.
Scleroderma affects approximately 300,000 people in the United States. It is four times as common in women than in men. Incidence rates are estimated at 2-20 per million per year in the United States.
Juvenile scleroderma affects approximately 7000 children in the United States. Most common form of Juvenile Scleroderma is Localized Scleroderma - Morphea and/or Linear.
SIGNS AND SYMPTOMS
Scleroderma affects the skin, and in more serious cases it can affect the blood vessels and internal organs. The most evident symptom is the hardening of the skin and associated scarring. Typically, the skin appears reddish or scaly. Blood vessels may also be more visible. Where large areas are affected, fat and muscle wastage will weaken limbs and affect appearance.
The seriousness of the disease varies hugely between cases. The two most important factors to consider are the level of internal involvement (beneath the skin) and the total area covered by the disease. For example, there have been cases where the patient has no more than one or two lesions, perhaps covering a few inches. Less serious cases tend not to involve the internal bodily functions.
There is discoloration of the hands and feet in response to cold. Most patients (over 80%) have Raynaud's phenomenon, a vascular symptom that can affect the fingers and toes.
Systemic scleroderma and Raynaud's can cause painful ulcers on the fingers or toes which are known as digital ulcers.
Calcinosis is also common in systemic scleroderma, and is often seen near the elbows, knees or other joints.
Histology of scleroderma and normal skin biopsies
Hematoxylin-eosin stained tissue sections from 4 systemic sclerosis (SSc1-4) patients with diffuse scleroderma from involved forearm skin (A-D) and one normal control (Nor4, E). Dermal collagen bundles are compacted and hyalinized with extention below the eccrine sweat glands into the reticular dermis. The eccrine sweat glands are reduced in size and the surrounding subcutaneous fat is decreased. Significant inflammatory infiltrates are not present. (X40)
Diffuse scleroderma can cause musculoskeletal, pulmonary, gastrointestinal, renal and other complications. Patients with larger amounts of cutaneous involvement are more likely to have involvement of the internal tissues and organs.
The first joint symptoms that patients with scleroderma have are typically non specific joint pains, which can lead to arthritis, or cause discomfort in tendons or muscles. Joint mobility, especially of the small joints of the hand, may be restricted by calcinosis or skin thickening. Patients who have progressed later in their disease may develop muscle weakness, or myopathy, either from the disease, or its treatments.
Some impairment in lung function is almost universally seen in patients with diffuse scleroderma on pulmonary function testing; however, it does not necessarily cause symptoms, such as shortness of breath. Some patients can develop pulmonary hypertension, or elevation in the pressures of the pulmonary arteries. This can be progressive, and lead to right sided heart failure. The earliest manifestation of this may be a decreased diffusion capacity on pulmonary function testing.
Other pulmonary complications in more advanced disease include aspiration pneumonia, pulmonary hemorrhage and pneumothorax.
Diffuse scleroderma can affect any part of the gastrointestinal tract. The most common manifestation in the esophagus is reflux esophagitis, which may be complicated by peptic stricturing, or benign narrowing of the esophagus. This is best initially treated with proton pump inhibitors for acid suppression, but may require bougie dilatation in the case of stricture.
Scleroderma can decrease motility anywhere in the gastrointestinal tract. The most common source of decreased motility involvement is the esophagus and the lower esophageal sphincter, leading to dysphagia and chest pain. As Scleroderma progresses, esophageal involvement from abnormalities in decreased motility may worsen due to progressive fibrosis (scarring). If this is left untreated, acid from the stomach can back up into the esophagus causing esophagitis, and GERD. Further scarring from acid damage to the lower esophagus many times leads to the development of fibrotic narrowing, also known as strictures which can be treated by dilitation, and Barrett's esophagus. The small intestine can also become involved, leading to bacterial overgrowth and malabsorption, of bile salts, fats, carbohydrates, proteins, and vitamins. The colon can be involved, and can cause pseudo-obstruction or ischemic colitis.
Rarer complications include pneumatosis cystoides intestinalis, or gas pockets in the bowel wall, wide mouthed diverticula in the colon and esophagus, and liver fibrosis. Patients with severe gastrointestinal involvement can become profoundly malnourished.
Scleroderma may also be associated with gastric antral vascular ectasia (GAVE), also known as watermelon stomach. This is a condition where atypical blood vessels proliferate usually in a radially symmetric pattern around the pylorus of the stomach. GAVE can be a cause of upper gastrointestinal bleeding or iron deficiency anemia in patients with scleroderma.
Renal involvement, in scleroderma, is considered a poor prognostic factor and not infrequently a cause of death in patients with scleroderma.
The most important clinical complication of scleroderma involving the kidney is scleroderma renal crisis . Symptoms of scleroderma renal crisis are malignant hypertension (high blood pressure with evidence of acute organ damage), hyperreninemia (high renin levels), azotemia (kidney failure with accumulation of waste products in the blood) and microangiopathic hemolytic anemia (destruction of red blood cells). Apart from the high blood pressure, hematuria (blood in the urine) and proteinuria (protein loss in the urine) may be indicative.
In the past scleroderma renal crisis was almost uniformily fatal. While outcomes have improved significantly with the use of ACE inhibitors the prognosis is often guarded, as a significant number of patients are refractory to treatment and develop renal failure. Approximately 10% of all scleroderma patients develop renal crisis at some point in the course of their disease. Patients that have rapid skin involvement have the highest risk of renal complications.
Treatments for scleroderma renal crisis include ACE inhibitors, which are also used for prophylaxis, and renal transplantation. Transplanted kidneys are known to be affected by scleroderma and patients with early onset renal disease (within one year of the scleroderma diagnosis) are thought to have the highest risk for recurrence.
RISK FACTORS AND CAUSES
A risk factor is something that increases your likelihood of getting a disease or condition.
It is possible to develop scleroderma with or without the risk factors listed below. However, the more risk factors you have, the greater your likelihood of developing scleroderma. If you have a number of risk factors, ask your healthcare provider what you can do to reduce your risk.
Factors that can increase your risk of developing scleroderma include:
The morphea type of scleroderma usually strikes people around 20-40 years old. Systemic scleroderma—be it limited or diffuse—is more likely to occur in people 30-50 years old.
Overall, women are three times as likely as men to develop scleroderma. During the ages of 30-55, women develop the disease at a rate 7-12 times higher than men. Researchers suspect that women may be at higher risk because of prior pregnancies (fetal cells may trigger an immune reaction) or the effects of estrogen, but more studies are needed to see if there is a link.
People who have family members with autoimmune diseases have an increased likelihood of developing scleroderma.
Young African-American women have a particularly high rate of scleroderma and tend to have more severe forms of the disease. Choctaw Native Americans in Oklahoma have an extremely high rate of scleroderma.
A number of environmental exposures seem to increase the risk of scleroderma, including:
Aniline-contaminated rapeseed oil (used for cooking)
There is no clear obvious cause for scleroderma and systemic sclerosis. Genetic predisposition appears to be limited: genetic concordance is small; still, there often is a familial predisposition for autoimmune disease. Polymorphisms in COL1A2 and TGF-β1 may influence severity and development of the disease. There is limited evidence implicating cytomegalovirus as the original epitope of the immune reaction, and organic solvents and other chemical agents have been linked with scleroderma.
Cytomegalovirus-associated cutaneous vasculopathy (CMV) and scleroderma sans inclusion body change . Viruses have long been held to be of pathogenetic importance in the evolution of autoimmune connective tissue disease. The role of tumor necrosis factor alpha blockers in scleroderma cases temporally associated with CMV infection requires further evaluation.
One of the suspected mechanisms behind the autoimmune phenomenon is the existence of microchimerism, i.e. fetal cells circulating in maternal blood, triggering an immune reaction to what is perceived as "foreign" material.
A distinct form of scleroderma and systemic sclerosis may develop in patients with chronic renal failure. This entity, nephrogenic fibrosing dermopathy or nephrogenic systemic fibrosis, has been linked to the exposure to gadolinium-containing radiocontrast.
Bleomycin (a chemotherapeutic agent) and possibly taxane chemotherapy may cause scleroderma, and occupational exposure to solvents has been linked with an increased risk of systemic sclerosis.
The pathogenesis of systemic sclerosis (or scleroderma) is complex and as yet incompletely understood. Immune activation, vascular damage, and excessive synthesis of extracellular matrix with deposition of increased amounts of structurally normal collagen are all known to be important in the development of this illness. These mechanisms result from cell-cell, cell-cytokine, and cell-matrix interactions. The heterogeneity in the clinical features of patients with scleroderma is most likely to be a reflection of the variable contributions from each of these pathogenic factors.
Most current hypotheses of the pathogenesis of scleroderma focus on the interplay between early immunological events and vascular changes, resulting in the generation of a population of activated fibrogenic fibroblasts generally considered to be the effector cell in the disease (show figure)
A review of the many factors felt to be involved in the pathogenesis of scleroderma is discussed here:
VASCULAR AND ENDOTHELIAL CHANGES — Vascular and endothelial cell changes , primarily mediating vascular tone, appear to precede other features of scleroderma.
Vasoconstriction — The following mediators of vascular tone may be important in the pathogenesis of scleroderma :
Nitric oxide (NO, or endothelium derived relaxing factor)
Endothelium derived constricting factors (EDCF)
Vascular endothelial growth factor
Derangements of endothelins, nitric oxide, and superoxide anions (which are inflammatory mediators), are currently felt to be the most significant mediators of altered vascular tone in scleroderma.
The overproduction of collagen is thought to result from an autoimmune dysfunction, in which the immune system would start to attack the kinetochore of the chromosomes. This would lead to genetic malfunction of nearby genes. T cells accumulate in the skin; these are thought to secrete cytokines and other proteins that stimulate collagen deposition. Stimulation of the fibroblast, in particular, seems to be crucial to the disease process, and studies have converged on the potential factors that produce this effect.
A significant player in the process is transforming growth factor ( TGFβ ). This protein appears to be overproduced, and the fibroblast (possibly in response to other stimuli) also overexpresses the receptor for this mediator. An intracellular pathway (consisting of SMAD2/SMAD3, SMAD4 and the inhibitor SMAD7) is responsible for the secondary messenger system that induces transcription of the proteins and enzymes responsible for collagen deposition. Sp1 is a transcription factor most closely studied in this context. Apart from TGFβ, connective tissue growth factor ( CTGF ) has a possible role.
Damage to endothelium is an early abnormality in the development of scleroderma, and this too seems to be due to collagen accumulation by fibroblasts, although direct alterations by cytokines, platelet adhesion and a type II hypersensitivity reaction have similarly been implicated. Increased endothelin and decreased vasodilation has been documented.
Jimenez & Derk describe three theories about the development of scleroderma:
The abnormalities are primarily due to a physical agent, and all other changes are secondary or reactive to this direct insult.
The initial event is fetomaternal cell transfer causing microchimerism, with a second summative cause (e.g. environmental) leading to the actual development of the disease.
Physical causes lead to phenotypic alterations in susceptible cells (e.g. due to genetic makeup), which then effectuate DNA changes which alter the cell's behavior.
Is anemia commonly associated with scleroderma?
Several types of anemia can occur in scleroderma patients and the treatment of the anemia depends on which type is present. Iron-deficiency anemia, usually from gastrointestinal blood loss, is common, and a search for where the blood loss is coming from is essential before iron supplementation is given.
Both anemia of chronic disease and hemolytic anemia are seen in scleroderma patients who have had renal crisis.
Diagnosis is by clinical suspicion, presence of autoantibodies (specifically anti-centromere and anti-scl70/ anti-topoisomerase antibodies ) and occasionally by biopsy. Of the antibodies, 90% have a detectable anti-nuclear antibody. Anti-centromere antibody is more common in the limited form (80-90%) than in the systemic form (10%), and anti-scl70 is more common in the diffuse form (30-40%) and in African-American patients (who are more susceptible to the systemic form).
There are three major forms of scleroderma: diffuse, limited (CREST syndrome ) and morphea/linear. Diffuse and limited scleroderma are both a systemic disease, whereas the linear/morphea form is localized to the skin. (Some physicians consider CREST and limited scleroderma one and the same, others treat them as two separate forms of scleroderma.) There is also a subset of the systemic form known as "systemic scleroderma sine scleroderma", meaning the usual skin involvement is not present.
Diffuse scleroderma (progressive systemic sclerosis) is the most severe form - it has a rapid onset, involves more widespread skin hardening, will generally cause much internal organ damage (specifically the lungs and gastrointestinal tract), and is generally more life threatening.
Limited scleroderma/CREST syndrome
The limited form is much milder: it has a slow onset and progression, skin hardening is usually confined to the hands and face, internal organ involvement is less severe, and a much better prognosis is expected.
In typical cases of limited scleroderma, Raynaud's phenomenon may precede scleroderma by several years. Raynaud's phenomenon is due to vasoconstriction of the small arteries of exposed peripheries - particularly the hands and feet - in the cold. It is classically characterised by a triphasic colour change - first white, then blue and finally red on rewarming. The scleroderma may be limited to the fingers - known as sclerodactyly.
The limited form is often referred to as CREST syndrome."CREST" is an acronym for the five main features:
Morphea/linear scleroderma involves isolated patches of hardened skin - there generally is no internal organ involvement.
There is no cure for every patient with scleroderma, though there is treatment for some of the symptoms, including drugs that soften the skin and reduce inflammation. Some patients may benefit from exposure to heat.
A range of NSAIDs (nonsteroidal anti-inflammatory drugs) can be used to ease symptoms, such as naproxen. If there is esophageal dysmotility (in CREST or systemic sclerosis), care must be taken with NSAIDs as they are gastric irritants, and so a proton pump inhibitor (PPI) such as omeprazole can be given in conjunction.
Immunosuppressant drugs, such as mycophenolate mofetil (Cellcept®) or cyclophosphamide are sometimes used to slow the progress. Digital ulcerations and pulmonary hypertension can be helped by prostacyclin (iloprost) infusion. Iloprost being a drug which increases blood flow by relaxing the arterial wall.
While still experimental (given its high rate of complications), hematopoietic stem cell transplantation is being studied in patients with severe systemic sclerosis; improvement in life expectancy and severity of skin changes has been noted.