Myalgia, weakness, long rash, beware of this disease!

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Fatigue, long red rash

What happened to them?

Ms. Wang (pseudonym), 63 years old, noticed a purple-red rash around her orbit two months ago, swelling was obvious, and the muscles in her arms and thighs also began to ache and weaken.

At the beginning of the disease, Ms. Wang did not pay attention to it, but later the weakness of the limb muscles became more and more serious, it was difficult to lift her arms, it was difficult to squat and stand up, and even normal life could not take care of herself.

Went to the local hospital for infusion treatment, the symptoms did not alleviate, and the purple-red rash began to grow to the front of the neck. A panicked Ms. Wang came to the Rheumatology and Immunology Department of Zhejiang University Shaw Hospital for help.

Mr. Li (pseudonym), 25, began to have fever 2 weeks ago and developed symptoms of fatigue.

At the same time, Mr. Li strangely found that his hands began to become rough, and a dark red rash appeared on the side of his hands and elbows behind his hands. He also began to have a dry cough, chest tightness and shortness of breath after activity, and after several twists and turns, Mr. Li also came to the Rheumatology and Immunology Department.

After examination and evaluation, both patients were eventually diagnosed with dermatomyositis.

What is dermatomyositis

Dermatomyositis is a subtype of idiopathic inflammatory myopathy (a systemic autoimmune disease) that involves primarily the skin and muscles.

The incidence is unknown, but it is more common in women, with a male-to-female incidence ratio of about 1: (2 to 3).

Dermatomyositis can occur at any age, but there are two peaks, 5 to 15 years and 45 to 65 years.

What are the symptoms of dermatomyositis?

Dermatomyositis usually has a subtle onset and progresses slowly.

Very few cases of illness are acute, with severe muscle weakness, chest tightness, dysphagia, and even respiratory failure within a few days. The details are as follows:

No.1

Muscle weakness

Predominantly symmetrical proximal muscle weakness, particularly in the neck, pelvis, thigh, and shoulder muscles, about half of patients have myalgia or muscle tenderness.

For example, scapular girdle muscle involvement will have difficulty raising the arm, and it is impossible to comb the hair and dress;

Cervical flexor involvement may cause difficulty in lying flat and looking up, and weakness in sitting on the back;

Laryngeal muscle involvement may cause dysphagia, hoarseness, and dysphonia;

Respiratory muscle involvement may cause chest tightness, dyspnea, and in severe cases require ventilator assistance;

Pelvic girdle muscle involvement may cause difficulty going up and down stairs, limited squatting, and difficulty walking.

No.2

rash

About half of patients have a rash that precedes muscle weakness, which may be different in different patients or at different times, and the rash and muscle weakness are not necessarily parallel. Typical rashes are as follows:

Gottron rash/sign

Raised purple-red papules or ulcerative rashes of the metacarpophalanges, interphalanges, elbows, and knee extensions are called Gottron rashes.

Positive rash

Bilateral edematous mauve spots around the orbit.

Shawl sign and V sign

Erythema diffuse on the back of the shoulders, neck, and front of the chest neckline.

Mechanic

Hyperkeratosis, desquamation, rough cracking of the skin of the fingers, especially on the radial side of the index finger.

Abnormal nail folds

Telangiectasia of the nail bed, peridothrychial erythema, nail epithelium overgrowth, etc.

No.3

Interstitial lung disease

More than 60% of patients develop interstitial lung disease, which presents with progressive dyspnea, and some patients have no lung symptoms. Because the onset is insidious, its symptoms are easily masked by the symptoms of muscle involvement.

No.4

other

There may also be nonspecific manifestations such as morning stiffness, fatigue, loss of appetite, weight loss, fever (moderate to low degree of fever, or even high fever), joint pain, and Raynaud's phenomenon. At the same time, some studies have confirmed that malignancy is associated with inflammatory myopathy, in which dermatomyositis has a higher incidence of malignancy.

Why do I get dermatomyositis?

The cause of dermatomyositis is currently unknown and may be related to the following factors:

Genetic factors

Dermatomyositis is associated with immune response genes and there is some familial clustering.

Infectious factors

Viral infection can induce autoimmunity, such as enteroviruses (influenza virus, coxsackie virus, Echo virus) and retroviruses (human T lymphocyte virus). Among them, enteroviral myositis is common in children, but is mostly self-limited.

In addition, staphylococcus, Clostridium, and Mycobacteria can also infect skeletal muscle and cause acute muscle inflammation. Parasites such as Toxoplasma gondii, Cruzepanosoma, and Spirochetes may initiate dermatomyositis.

environmental factors

The incidence of dermatomyositis varies greatly geographically and ethnically. Epidemiological studies have found that the closer you are to the equator, the higher the incidence of dermatomyositis, suggesting that UV exposure may be one of the environmental risk factors to promote dermatomyositis progression.

Other environmental factors, such as smoking and occupational factors (dust, gas, and smoke inhalation), are also risk factors for dermatomyositis and can increase the incidence of interstitial lung disease.

Malignancy may be another risk factor for dermatomyositis. Patients with dermatomyositis have been found to have an increased risk of malignancy within 10 years of diagnosis.

A recent study found an association between dermatomyositis and hypertension, diabetes mellitus, and ischemic heart disease, so a comprehensive vascular disease risk factor assessment in patients with dermatomyositis is necessary.

Autoimmune response

It has been associated with abnormal antibodies in the patient's body attacking their own tissues.

How is dermatomyositis diagnosed?

Clinical manifestations

Skin manifestations: gottron papules located in the interphalangeal joints, metacarpophalanges, elbow joints, knees and ankles, positive rashes located around the orbit, purple-red rashes located in the V-shaped area of the front of the neck and the back of the shoulders, purple-red rashes located on the outside of the thighs, thickening, roughness, keratinization, cracking, and scaling of the skin of the fingers and the palmar surface of the hands.

Muscle manifestations: symmetrical proximal muscle weakness.

Laboratory tests

Elevated serum creatine kinase;

Electromyography and muscle magnetic resonance can effectively identify muscle inflammation;

Muscle biopsy can confirm muscle inflammation;

Testing for myositis-specific autoantibodies is helpful in confirming the diagnosis.

With the deepening of research on dermatomyositis, the detection of myositis antibodies has also highlighted its unique value, which plays an important role in the classification of dermatomyositis, early diagnosis and evaluation of patient prognosis.

Prognosis of dermatomyositis

Dermatomyositis is a group of diseases with a poor prognosis and a higher mortality rate in hospitalization in rheumatism.

Interstitial lung disease is a common lung complication in patients with dermatomyositis and is one of the main factors contributing to poor prognosis and increased mortality in patients with dermatomyositis, with the presence of interstitial lung disease detected at the time of diagnosis in about 65% of patients with dermatomyositis. Some of these patients may present with rapidly progressive interstitial lung disease, which can progress rapidly over a period of days to weeks, develop respiratory failure, and have a very high mortality rate.

Therefore, early diagnosis and early treatment are important to improve the prognosis of dermatomyositis. The treatment of dermatomyositis involves many aspects, including drug and non-drug treatment, and the current treatment drugs for dermatomyositis patients mainly include hormones, immunosuppressants, biologics, plasma exchange, etc.

In short, the treatment of dermatomyositis is a repetitive and lengthy process, doctors and patients need to fully cooperate, patients need to use drugs under the guidance of doctors, monitor the condition, prevent and evaluate adverse drug reactions, etc.

Source: Department of Rheumatology and Immunology, Run Run Shaw Hospital

Original works, reprinted please indicate the source and source

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