Myositis Overlap Diseases: Scleroderma
June is Scleroderma Awareness Month and an opportunity to highlight another frequently-seen overlap with Myositis. The word “scleroderma” means “hard skin” and is believed to be caused by an overproduction of collagen. Like most forms of Myositis, it is considered a chronic autoimmune disease primarily affecting the connective tissue, which is tissue that supports organs and other parts of the body.
Approximately 300,000 people in the US have Scleroderma as compared to an estimated 50,000 to 75,000 people with Myositis.
There are two primary categories of Scleroderma: Localized and Systemic.
LOCALIZED SCLERODERMA typically affects the skin and/or muscles but rarely anything else. The two types within this category which are most often seen are Morphea and Linear.
Morphea is characterized by waxy, and often thick patches on the skin, which can be any color, shape or size.
Linear is usually a waxy line or streak appearing on the arm, leg or forehead and usually starts in childhood. The linear form can involve deeper layers of the skin, which can cause constriction of the joints, and approximately 10-20% of people with Linear Scleroderma will develop joint pain.
SYSTEMIC SCLERODERMA: The term “systemic” means that the hardening is occurring internally in addition to the skin. Nearly everyone with Systemic Scleroderma, also referred to as Systemic Sclerosis, tests positive to the ANA (Anti-nuclear Antibodies). The two primary categories which fall under the systemic type are Diffuse and Limited. Hardening can occur in various parts of the body affecting blood vessels, kidneys, heart, lungs, digestive system, muscles, joints and more.
Diffuse Scleroderma is the more serious form of Scleroderma because internal organs are generally affected such as the gastrointestinal tract, heart, lungs or kidneys. Of particular concern are Pulmonary Fibrosis and Pulmonary Hypertension. The degree of organ involvement varies significantly from patient to patient.
Also in Diffuse, the skin of the arms, legs and trunk are more likely to be involved. The tightened skin can make it difficult to bend fingers, hands, and other joints, and inflammation of the joints, tendons and muscles can also occur. Tight skin on the face can reduce the size of a person’s mouth necessitating good dental care.
Limited Scleroderma is often referred to as CREST because the individual letters in C-R-E-S-T represent the first initial of the following conditions:
- Calcinosis is the formation of calcium deposits on soft tissue which can appear as small white lumps which form under the skin. The lumps may appear anywhere but most commonly occur on the hands, especially the fingers, or near joints such as elbows or knees. These lumps may break through the skin and leak white liquid. Calcinosis may range from a small lump to large clusters, which can be very painful, a symptom also seen in Dermatomyositis, especially Juvenile Dermatomyositis.
- Raynaud’s is a condition which causes some areas of the body, most often fingers and toes, to feel numb and cold in response to cold temperatures or stress. Small arteries that supply blood to the skin become narrow, which limits blood circulation to affected areas. The areas impacted can turn white, blue and/or red. Raynaud’s is also commonly seen in people with Myositis.
- Esophageal Dysfunction is caused when the sphincter of the esophagus does not close as it should which results in backwash of stomach acid causing heartburn and possible damage to the lining of the esophagus.
- Sclerodactyly involves tightening of the skin and is the most classic symptom of Scleroderma. Typically the initial manifestation of this condition is swelling of the fingers, but as it progresses, the skin of the fingers and toes becomes hard and shiny. The fingers can become difficult to bend and can form contractures (shortening of the muscle or joint) due to severe tightening of the skin.
- Telangiectasias are small, dilated blood vessels close to the surface of the skin, which are usually considered harmless.
However, additional conditions have been found in Limited Scleroderma such as dilated capillary loops at the base of the fingernails, skin ulcerations and skin hypo- and hyperpigmentation. While internal organs may be affected in Limited Scleroderma, they are less frequent than in the Diffuse form.
As in many autoimmune diseases, Scleroderma is a complicated condition that is often misdiagnosed because it can mimic other autoimmune diseases, and no accurate diagnostic test currently exists. Symptoms vary from person to person and can range from mild to life- threatening depending upon what part of the body is most affected.
Currently, there is no cure for Scleroderma, however, most of the individual symptoms can be controlled or minimized with medications. For instance, heartburn can be controlled by medications called proton pump inhibitors (PPIs). Sometimes, just as with Myositis, immunosuppressant drugs are used to suppress the immune system. Some people with mild disease may not need medication at all and occasionally people can go off treatment when their Scleroderma is no longer active.
It is recommended that prompt diagnosis and treatment by a rheumatologist, dermatologist or another physician trained in skin, systemic and autoimmune diseases can potentially reduce the seriousness of the disease or help prevent irreversible damage.