Dermatomyositis: All about the rare inflammatory disease

The sudden death of actor Suhani Bhatnagar, a 19-year-old actor seen in popular Bollywood film Dangal, due to dermatomyositis, has put the spotlight on this rare inflammatory disease. An autoimmune condition, it causes muscle weakness and skin rash. There is no cure for dermatomyositis, but the symptoms can be alleviated with medication, physical therapy and exercise. Let us tell you what dermatomyositis is and its symptoms.

What is dermatomyositis?

Dermatomyositis is a rare inflammatory disease that affects the muscles and the skin, says rheumatologist Dr Priyanka Kharbanda. It is classified as a type of autoimmune myositis, meaning the body’s immune system mistakenly attacks its own muscle and skin tissues. Going by a 2010 study published in JAMA Dermatology, it seems to be more common in women than in men.

What are the symptoms of dermatomyositis?

The symptoms of dermatomyositis can vary widely from person to person, but common signs and symptoms may include –

1. Distinctive skin rash

This skin rash can be seen on the eyelids, elbows, knuckles, chest, knees, and back. It may be either reddish or purple in colour.

2. Muscle weakness

Dermatomyositis typically affects the muscles closest to the trunk of the body, such as those in the hips, thighs, shoulders and upper arms. Due to weakness, it may be difficult to perform even simple activities like climbing stairs or lifting objects.

3. Fatigue

People with dermatomyositis may experience profound fatigue that is not relieved by rest. This can have a major impact on daily functioning as well as quality of life.

4. Swelling

Joint pain and swelling may occur in some people with dermatomyositis. The wrists, fingers, and knees may be particularly affected.

5. Fever

The onset or flare-ups of dermatomyositis may be accompanied by a fever. It will usually be a low-grade fever.

6. Dropped head syndrome

People with dermatomyositis may also experience weakness in the muscles of the neck. It can involuntarily make the head to drop forward, which is a condition known as “dropped head syndrome.”

7. Lung disease

Some people may develop interstitial lung disease, says Dr Kharbanda. It can cause shortness of breath, coughing, and decreased exercise tolerance.

Some may even experience dysphagia, or difficulty swallowing, which can lead to choking.

What are the causes of dermatomyositis?

While the exact cause is unknown, several factors may increase the risk of developing dermatomyositis:

• There appears to be a genetic predisposition to dermatomyositis, as it can run in families.
• Dermatomyositis can occur at any age, but it most commonly affects adults in their late 40s to early 60s, and teens and children as young as five-year-old.
• Some environmental factors such as exposure to ultraviolet light, may trigger or exacerbate dermatomyositis in people.
• Dermatomyositis can sometimes be associated with other autoimmune diseases, such as lupus or rheumatoid arthritis. Having one autoimmune disease may increase the risk of developing another.

A 2022 study published in the Medeniyet Medical Journal also found a link between Covid-19 and dermatomyositis. Muscular weakness, rashes and interstitial lung disease were some of the symptoms of Covid-19-induced dermatomyositis.

How is dermatomyositis diagnosed?

The diagnostic process may involve the following:

1. Medical history and physical examination

The doctor will typically begin by taking a detailed medical history and conducting a physical examination. They will inquire about symptoms such as muscle weakness, skin rashes, difficulty swallowing, and other relevant signs.

2. Tests

Several tests and scans may be ordered to help diagnose dermatomyositis and rule out other conditions, says Dr Kharbanda. These may include:

• Muscle Enzyme Tests: Muscle enzymes like aldolase may be measured.
• Electromyography (EMG): It measures the muscles’ electrical activity. It can help identify abnormal electrical patterns characteristic of muscle diseases.
• Muscle biopsy: A small sample of muscle tissue may be taken for examination under a microscope. This can help confirm inflammation and damage to the muscle tissue characteristic of dermatomyositis.
• Skin biopsy: If skin changes are present, a biopsy of the affected skin may be performed to examine it under a microscope. This can help confirm the diagnosis of dermatomyositis and rule out other skin conditions.
• Imaging Studies: MRI (Magnetic Resonance Imaging) or CT (Computed Tomography) scans may be ordered to assess the extent of muscle involvement and detect inflammation.

Can a person live a full life with dermatomyositis?

While dermatomyositis can pose challenges, many people with the condition can live full and meaningful lives with appropriate management and support, says the expert. They need to work closely with their healthcare team to develop a comprehensive treatment plan tailored to their specific needs and goals.
There are medications, such as corticosteroids and immunosuppressants,
that help to suppress the immune system’s abnormal activity. Exercise and physical therapy are also suggested, so that muscle strength and function are maintained.

Early diagnosis followed by treatment are important in managing dermatomyositis.