Dermatomyositis is an inflammatory condition of the skin and muscles. Regions of inflammation can calcify, especially when the disease strikes children and adolescents, and the condition can spread from skin and muscles to the esophagus, lungs, and sometimes the heart.
In dermatomyositis, there is usually "proximal" muscle weakness rather than the "distal" muscle weakness found in other conditions. The muscles in the arms and legs closest to the trunk of the body become weak first. The muscles around the esophagus can also be affected so swallowing becomes difficult. Inflammation of the intracostal muscles can make breathing difficult. The condition usually causes a characteristic purple rash over the upper eyelids. Muscles don't visibly atrophy until late in the disease, but weakness can be a major problem in just a matter of weeks.
Dermatomyositis an idiopathic condition, that is, nobody really knows why it happens. However, there are abnormal antigens associated with the tissue destruction caused by the disease, and an infection with Lyme disease, toxoplasmosis, parvovirus, or HIV can trigger the production of those antigens. Symptoms may be set off by some medications, including cholesterol-lowering statins, penicillamine or cyclophosphamide for cancer treatment, Bacillus Calmette-Guérin (BCG) vaccine, also used in cancer treatment, or the steroid phenylbutazone. Repeated exposure to these drugs results in worse symptoms and lower rates of survival. Clotting disorders of the sort that cause more clotting, not less, make the disease much worse in all age groups, but especially in the elderly. A MTHFR mutation (methylenetetrahydrofolate reductase), which affects the way the body can use the B vitamin folic acid, can make symptoms worse, unless the person who has the mutation takes methylfolate to compensate for the body's inability to make the enzyme to use folic acid.
Sometimes cancer is discovered after the appearance of nodules from dermatomyositis, but it's more likely that the dermatomyositis is due to the cancer, not the other way around.
Dermatomyositis tends to remit and relapse. Symptoms get better and worse without any obvious explanation.
How long do people survive after they are diagnosed with this condition?
While the symptoms usually are severe, death from "fulminant" dermatomyositis only results in about 5 percent of cases. Those who die of the disease are usually people who were 60 years of age or older when first diagnosed. People who have already had a heart attack, or who have chronic lung conditions like emphysema, are much more likely to be those who succumb to the disease. The immediate cause of death usually is a breathing difficulty.
Another 25 percent of people who are diagnosed with dermatomyositis are also eventually diagnosed with a malignancy. Women who have dermatomyositis have a significantly elevated risk of developing ovarian cancer. People in certain Asian groups who have dermatomyositis and who smoke are at much higher than normal risk of nose and throat cancers. Breast, colon, lung, prostate, and blood cancers have been noted in dermatomyositis patients.
The majority of people who develop this disease, however, will die of something else. Often survival is a matter of navigating the predictable problems of the disease:
- Men with dermatomyositis are more likely to have cancer than women who have the disease. Predictors of cancer are dysphagia (the inability to swallow) and a high value on a blood test of the sedimentation ("sed") rate.
- Calcinosis, the development of calcium deposits, is more common in children than in adults. It's especially important to detect calcinosis early in children so they can stay physically active. Children who are not able to move and play also tend to develop contractures, shortening and hardening of muscles and tendons that make the joints rigid.
- Osteoporosis is about three times more common in women who have osteoporosis than in women who do not. Early intervention can help preserve bone mass.
- Blood clots are a special problem during the first year of the disease. In older people who have atherosclerosis, especially in those who have both atherosclerosis and clotting disorder or a MTHFR mutation, cardiovascular care is essential.
Africans and African-Americans are usually diagnosed later than people in other groups because doctors don't notice skin symptoms. The sooner you are treated, no matter what your race, the better your long-term outlook.
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