Dermatomyositis: Definition, Causes, Symptoms, Diagnosis, and Treatment

Author: Thomas C. Weiss
Published: 2009/05/21 - Updated: 2018/03/16
Peer-Reviewed: N/A
Contents: Summary - Main - Related Publications

Synopsis: Dermatomyositis is an acquired myopathy disease which affects muscles and is characterized by a distinctive skin rash and inflammation.

While the disease is rare, it can happen to persons of any age, although it commonly affects adults who are between the ages of forty and sixty, or children between the ages of five and fifteen years. Women tend to experience dermatomyositis more often than men.

Main Digest

While the disease is rare, it can happen to persons of any age, although it commonly affects adults who are between the ages of forty and sixty, or children between the ages of five and fifteen years. Women tend to experience dermatomyositis more often than men.

Dermatomyositis is an acquired myopathy disease which affects a person's muscles that is characterized by both a distinctive skin rash and inflammation. While the disease is rare, it can happen to persons of any age, although it commonly affects adults who are between the ages of forty and sixty, or children between the ages of five and fifteen years. Women tend to experience dermatomyositis more often than men.

Dermatomyositis develops over a period of weeks or months. Persons with the disease can experience periods of remission when their symptoms spontaneously improve. There are treatments available that can improve not only the person's muscle function and strength, but their skin as well.

Causes of Dermatomyositis

Medical science does not know what causes dermatomyositis, although it believes that the disease is caused by a viral infection of the person's muscles, or perhaps an issue with the body's immune system. The disease is considered by medical science to be one of the connective tissue diseases in the same category as lupus erythematosus or systemic sclerosis. Research into dermatomyositis involves factors that may be involved, such as an autoimmune defect, an underlying cancer, genetic predisposition, the potential that the disease may be drug-induced, or that it may be triggered by either a toxic or an infectious agent.

Many doctors believe that inflammatory myopathies such as dermatomyositis can be caused by an infection via bacteria, viruses, or parasites. With dermatomyositis, doctors are unable to connect an infection with the disease in the majority of cases. There are some doctors who believe that some persons have a genetic predisposition to dermatomyositis.

A person's immune system usually works in order to protect their body from being attacked by foreign substances like viruses and bacteria. Persons with dermatomyositis experience an unknown cause which appears to trigger their immune system, initiating production of autoimmune antibodies which then attack their own tissues. The person's small blood vessels in their muscular tissues seem to be affected in particular. Inflammatory cells surround the person's blood vessels, eventually leading to degeneration of their muscle fibers. A number of person's with the disease present detectable levels of autoimmune antibodies in their bloodstream.

Symptoms of Dermatomyositis

Dermatomyositis can involve a number of different symptoms. People with the disease experience symptoms that may affect their muscles, or their skin through tell-tale rashes. Muscle weakness can involve the person's shoulders and hips, leading to difficulty in performing activities of daily living such as brushing their hair or working with their arms over their head. The person affected may experience difficulty holding their head up. Climbing stairs or getting up out of a chair may become difficult. Muscle weakness can show up suddenly, or it may develop slowly over a period of weeks or months.

Muscle weakness and the skin rash associated with dermatomyositis commonly appear at the same time, although the muscle weakness may occur first by a few weeks. At other times just the opposite is true, with the skin rash appearing before the muscle weakness. There are some persons, particularly children and teenagers, who develop either white or yellow lumps underneath their skin referred to as, 'Calcinosis,' that show up most often on their fingers or joints. These calcinosis may protrude through their skin and could potentially become infected as well.

Other persons experience swollen joints and, 'Raynaud's,' phenomenon - something that refers to fingers which become both white and stiff under cold conditions, then become purple again as they warm up. Children with dermatomyositis can experience skin that becomes thick and hard; when this occurs it is referred to as, 'Sclerodermatomyositis.' The rash associated with dermatomyositis can appear on a person's back, knuckles, chest, shoulders, neck, and face. Symptoms of dermatomyositis can include:

Diagnosing Dermatomyositis

A doctor has several means of diagnosing dermatomyositis, although the rash associated with the disease is often enough to establish a diagnosis. The doctor will ask the person about their family and personal medical history, as well as perform a physical examination. A number of additional tests, including blood testing, may be involved in the diagnostic process. Persons who are over the age of sixty may have a full-body examination in order to look for any forms of underlying cancer as well. Evaluation of the person's muscle strength is something else a doctor will pursue. The tests that may be involved in diagnosing dermatomyositis can include:


Electromyography involves insertion of a thin needle electrode through the person's skin into the muscle that is being tested. Electrical activity is measured as the person relaxes or tightens their muscle. Changes in the pattern of electrical activity may confirm a muscle disease. The doctor can then determine the distribution of the disease by testing different muscles.

Blood analysis:

Blood analysis will let your doctor know if the person being tested has elevated levels of muscle enzymes, such as creatine kinase and aldolase. Increased creatine and aldolase levels may indicate muscle damage. Blood testing may also help to determine whether the person has autoimmune antibodies in their bloodstream. In some persons, certain types of autoimmune antibodies have been associated with symptoms or signs of dermatomyositis; lung or skin involvement, for example. The information gained from blood testing can assist a doctor in development of an appropriate treatment plan.

Muscle Biopsy:

A Muscle Biopsy involves the surgical removal of a small amount of muscle tissue for laboratory analysis. The tissue can show a doctor abnormalities that may be present in the person's muscles, such as damage, infection, or inflammation. The sample can also be examined for enzyme deficiencies and any abnormal proteins that may be present.

Skin Biopsy:

A Skin Biopsy involves removal of a small piece of skin for analysis. A skin sample can assist in confirmation of a diagnosis of dermatomyositis, ruling out other disorders. Should the skin sample confirm a diagnosis of dermatomyositis, a muscle biopsy would not be required.

Magnetic Resonance Imaging (MRI):

An MRI scanner creates cross-sectional images of the person's muscles from information which is generated through magnetic fields and radio waves. The images may be viewed from any direction or plane. The scans can assist in detection of inflammation in the person's muscles.

Treating Dermatomyositis

The main goals in treating dermatomyositis are to control the skin disease and the muscle disease associated with dermatomyositis. Most persons with the disease need treatment throughout their lifetime, although around twenty-percent of those affected experience complete resolution. Those who have dermatomyositis and experience affects related to their heart or lungs and also have an underlying cancer may ultimately die from the disease. If a person does have dermatomyositis that is associated with a tumor, the muscle weakness they experience, as well as the rash, may improve once the tumor is removed.

Medications used in treatment of dermatomyositis include intravenous immunoglobulin. Prednisone is a medication many people with dermatomyositis take regularly. There are some additional medications that can be used to treat symptoms of the disease. These medications are:

Persons with dermatomyositis can be at increased risk of infections such as digestive and respiratory infections. Because of these risks, a doctor might monitor their symptoms and signs for indications of infection so they may receive prompt and appropriate treatment for any infections that may arise. When a person's muscles become severely inflamed, bed rest is recommended. Physical therapy and activity can help to keep joints and muscles moving. Use of sunscreen and avoidance of excessive exposure to the sun can help to protect the skin of person's affected by this disease. Person's with dermatomyositis should avoid eating food prior to bedtime and raise the head of their bed if they have difficulty with swallowing.

Author Credentials:

Thomas C. Weiss is a researcher and editor for Disabled World. Thomas attended college and university courses earning a Masters, Bachelors and two Associate degrees, as well as pursing Disability Studies. As a Nursing Assistant Thomas has assisted people from a variety of racial, religious, gender, class, and age groups by providing care for people with all forms of disabilities from Multiple Sclerosis to Parkinson's; para and quadriplegia to Spina Bifida. Explore Thomas' complete biography for comprehensive insights into his background, expertise, and accomplishments.

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