People with polymyositis often do not experience symptoms at the onset of immune-mediated muscle cell damage. Weakness occurs when at least 50% of muscle cells become damaged, so the patient experiences progressive muscle weakness spanning three to six months. In polymyositis, the muscle weakness is always symmetrical and the areas of involvement may fluctuate from time to time. Unlike in dermatomyositis, skin rash is rare in polymyositis.

A patient with polymyositis may be unable to perform motor functions due to muscle weakness. Things like getting up from a chair, climbing stairs or lifting become difficult. The patient may also complain difficulty on swallowing and lifting the head as the flexor muscles of the neck becomes affected. Some cases of polymyositis have manifestations of muscle weakness in the orbital muscles. Rare cases also have weaknesses in facial and bulbar muscles.

Aside from muscle weakness, a person with polymyositis may or may not experience myalgia. Polymyositis patients may also experience other symptoms such as morning stiffness, fatigue and anorexia, fever and weight loss. In addition, people with polymyositis may also have arthralgia and arthritis [6].
Polymyositis can also manifest symptoms like nasal regurgitation, reflux esophagitis, bloating and constipation and odynophagia.

Rarely, kidney problem is present in polymyositis. In some cases, polymyositis can affect the muscles of the heart. The patient may suffer from arrhythmias, conduction defects and myocarditis and pericarditis. People with polymyositis may suffer from serious heart problems like pulmonary hypertension and congestive heart failure. Dyspnea is also seen in rare cases of polymyositis, which is caused by weakening of muscles involved in breathing.
The patient may be unable to execute fine motor movements in later stages of the disease. Symptoms of dysphagia and dysphonia are often signs of poor prognosis.

Patients with polymyositis may also have chronic connective tissue disorders such as Sjögren syndrome, rheumatoid arthritis, lupus, mixed-connective tissue disease and scleroderma.

• Fever

  Familial Mediterranean fever (FMF) is an autosomal recessive disease affecting populations surrounding the Mediterranean area. In this case report, we report a Japanese female patient with polymyositis (PM) who presented with periodic fever. [ncbi.nlm.nih.gov]

• Fatigue

  Muscle weakness versus fatigue It may be easy to confuse muscle weakness with the general feeling of tiredness and weariness caused by fatigue. Both symptoms can occur as a result of polymyositis. Muscle weakness is a loss of strength. [dmpmandyou.com]

  Related Reading: Myasthenia gravis, a neuromuscular disease, causes voluntary muscle weakness and fatigue Myasthenia gravis, a neuromuscular disease, causes voluntary muscle weakness and fatigue. [belmarrahealth.com]

  Primary symptoms may include muscle pain and soreness, fatigue, trouble swallowing, and difficulty breathing. In the United States, there are an estimated 1,600 to 3,200 new cases per year and 50,000 to 75,000 people living with myositis. [healthline.com]

  Disabling Symptoms of Polymyositis and Dermtomyositis Symptoms of polymyositis and dermtomyositis can include: muscle weakness, usually close to the trunk of the body fatigue, and shortness of breath. [disabilitysecrets.com]

  Fatigue Difficulty swallowing or speaking Shortness of breath As the symptoms of polymyositis worsen, it may become difficult to raise your head when lying down, or to stand up from a seated position. [muirortho.com]

• Weight Loss

  […] rashes on connective skin (Gottron’s papules/sign) Roughened, dry skin on palms and fingers (mechanic’s hands) Polymyositis Gradual onset of proximal muscle weakness Fatigue, general discomfort, weight loss, low-grade fever Acthar is an FDA-approved [actharrheumatology.com]

  In addition to progressive muscle weakness, swelling and tenderness, people with polymyositis may have shortness of breath, fatigue, joint pain, fever, difficulty swallowing or speaking, loss of appetite, and weight loss. [kidshealth.org]

  Myositis types: Dermatomyositis and polymyositis Dermatomyositis and polymyositis share many symptoms, including: Weak and tired muscles Inflamed muscles Generally feeling unwell Weight loss Night sweats What sets the two apart is that in dermatomyositis [belmarrahealth.com]

  Weight loss and poor nutrition may become a problem if muscle weakness leads to trouble eating and swallowing. How is polymyositis diagnosed? The process starts with a health history and a physical exam. [uchealth.com]

• Hodgkin Lymphoma

  We report a 30-year-old man with Hodgkin's lymphoma who developed acute polymyositis following treatment by DLI 4 months post-allogeneic HSCT. The patient developed fever and generalized myalgia 22 days after a single dose of DLI. [ncbi.nlm.nih.gov]

  Other less frequently reported neoplasms include colorectal cancer, and non-Hodgkin lymphoma, pancreatic, gastric, and bladder cancer (see these terms). [orpha.net]

  The specific malignancies associated with polymyositis are lung cancer, nasopharyngeal cancer and non-Hodgkins lymphoma. Treatment and prognosis Polymyositis has no cure. However, there are several available treatment options for the symptoms. [news-medical.net]

  Frequency of specific cancer types in dermatomyositis and polymyositis: a population-based study. conclude that dermatomyositis and polymyositis are associated with specific cancer types, most notably ovarian, lung, pancreatic, and non-Hodgkin lymphoma [thelancet.com]

• Difficulty Climbing Stairs

  Progressive muscle weakness starts in the proximal muscles (muscles closest to the trunk of the body) which eventually leads to difficulties climbing stairs, rising from a seated position, lifting objects, or reaching overhead. [ninds.nih.gov]

  As the disease progresses and muscle power is lost, patients may experience a range of symptoms, including: Muscle weakness, usually in those that are closest to the body's trunk Loss of strength, difficulty climbing stairs, getting up from a chair, or [tuh.templehealth.org]

  You’ll have difficulty climbing stairs, getting up from a chair, or lifting objects with your arms. Fatigue, on the other hand, is more or less feeling like you simply cannot get out of bed all day. Both of these symptoms can be troublesome. [dmpmandyou.com]

• Respiratory Insufficiency

  Respiratory insufficiency as a result of respiratory muscle involvement could also be observed. Here we report a fortyone-year-old man who attended to the hospital with the complaints of shortness of breath and chest pain that have suddenly started. [dergipark.org.tr]

  It is likely that complication with respiratory infection further accelerates the progression of respiratory insufficiency in a patient with PM/DM-ILD requiring intensive immunosuppressive therapies, resulting in a fatal event. [arthritis-research.biomedcentral.com]

• Dysphagia

  Dysphagia and myositis Dysphagia is difficulty swallowing and it can be a complication of myositis. In order to swallow the body goes through three phases: oral, pharyngeal and esophageal. [belmarrahealth.com]

  In her history, she had upper and lower limbs weakness accompanied by dysphagia which was further complicated by right bronchial aspiration 9 months ago. [ncbi.nlm.nih.gov]

  […] biopsies Prognostic factors Response to therapy is variable - older patients at diagnosis do worse In one study, the 10 year survival rate was 50%; the main cause of death was circulatory followed by "musculoskeletal" ( Clin Rheumatol 2006;25:234 ) Dysphagia [pathologyoutlines.com]

  Other nonspecific symptoms include fatigue, weight loss, myalgia, arthralgia, dyspepsia, and dysphagia. PM can manifest in a variety of organ systems. [visualdx.com]

• Loss of Appetite

  In addition to progressive muscle weakness, swelling and tenderness, people with polymyositis may have shortness of breath, fatigue, joint pain, fever, difficulty swallowing or speaking, loss of appetite, and weight loss. [kidshealth.org]

  You may also have: Fatigue Fever Joint pain Loss of appetite Morning stiffness Weight loss Treatment The main treatment is the use of corticosteroid medicines. The dose of medicine is slowly tapered off as muscle strength improves. [account.allinahealth.org]

  You may also have: Fatigue Fever Joint pain Loss of appetite Morning stiffness Weight loss Skin rash on the back of the fingers, on the eyelids, or on the face Exams and Tests Tests may include: Autoimmune antibodies and inflammation tests CPK Serum aldolase [m.ufhealth.org]

• Heart Disease

  Keep in Mind Polymyositis is a serious disease than can result in life-threatening complications such as heart disease, lung disease, and pneumonia. With treatment, however, most people see improvement in their condition. [kidshealth.org]

  Should polymyositis be present, other conditions often are as well, including: Cancer Heart disease, particularly congestive heart failure or heart arrhythmia Lung disorders and diseases that result in scarring of lung tissue Lupus Rheumatoid arthritis [templehealth.org]

  Thirty‐seven patients (46.3%) died as a direct result of heart disease. Conclusions: Heart abnormalities are frequent in patients with PM/DM, most of which were subclinical. The efficacy of glucocorticoids and immunosuppressants is uncertain. [doi.org]

• Muscle Weakness

  Weakness occurs when at least 50% of muscle cells become damaged, so the patient experiences progressive muscle weakness spanning three to six months. [symptoma.com]

  Abstract Polymyositis is an idiopathic inflammatory myopathy of unknown aetiology that affect skeletal muscles causing symmetrical, proximal muscle weakness, and also other internal organs. [ncbi.nlm.nih.gov]

  From Wikidata Jump to navigation Jump to search rare idiopathic inflammatory myopathy characterized by symmetric proximal muscle weakness and elevated muscle enzymes edit English polymyositis rare idiopathic inflammatory myopathy characterized by symmetric [wikidata.org]

• Myopathy

  Drug interactions increase the risk of statin-associated toxic myopathy, but no risk factors for statin-associated inflammatory myopathies have been established. [ncbi.nlm.nih.gov]

  Although classified as an inflammatory myopathy, inclusion body myositis shows minimal evidence of inflammation. This is the most common inflammatory myopathy in patients older than age 50 years. [emedicine.medscape.com]

• Proximal Muscle Weakness

  Polymyositis-like syndrome in hypothyroidism is a rare condition characterised by proximal muscle weakness and elevated muscle enzymes. [ncbi.nlm.nih.gov]

  From Wikidata Jump to navigation Jump to search rare idiopathic inflammatory myopathy characterized by symmetric proximal muscle weakness and elevated muscle enzymes edit English polymyositis rare idiopathic inflammatory myopathy characterized by symmetric [wikidata.org]

  DEFINITION Polymyositis is an idiopathic inflamatory myopathy that causes symmetrical proximal muscle weakness, elevated skeletal muscle enzyme levels,characteristic electromyograhic pattern and muscle biopsy findings. 4. [de.slideshare.net]

• Myalgia

  The evolution was slowly favorable for the respiratory impairment, but the patient developed exacerbated myalgia, muscle weakness, reaching even the impossibility of maintaining orthostatism, and also joint pain. [ncbi.nlm.nih.gov]

  Myalgia means muscle pain or aching. An example of a myalgia would be the ailment fibromyalgia. [belmarrahealth.com]

• Muscle Tenderness

  Myalgia and muscle tenderness may occur in a small number of patients, usually early in the disease, and particularly in DM associated with connective tissue disorders. [accessmedicine.mhmedical.com]

  The result of this attack on the muscles is inflammation, with muscle tenderness as an occasional complaint. The onset of symptoms may be acute, but the condition usually progresses slowly. [bcm.edu]

  People with polymyositis often complain of joint and muscle tenderness. Conventional Treatment There is no cure for polymyositis. Corticosteroids are used to suppress the immune system as well as other drugs classified as immunosuppressants. [livestrong.com]

  Muscle Symptoms Weakness develops subacutely, over weeks to months, is symmetric and primarily involves the proximal muscles of the neck, shoulders, and pelvic girdle. Myalgias are also often present with involved muscles tender to palpation. [pathwaymedicine.org]

• Limb Weakness

  In her history, she had upper and lower limbs weakness accompanied by dysphagia which was further complicated by right bronchial aspiration 9 months ago. [ncbi.nlm.nih.gov]

  Many people with significant limb weakness also find activities such as swimming helpful in maintaining muscle function. Exercise will also help avoid weight gain. [musculardystrophyuk.org]

  After 1 month, he developed weakness of the left upper limb. One month later, he developed swallowing difficulty, neck drop and facial weakness without extraocular muscle weakness. [annalsofian.org]

  Patients Patients with clinical evidence of polymyositis based on symmetric proximal limb weakness, raised serum skeletal muscle enzyme levels, and abnormal findings on electromyography were referred for whole-body scanning. [ajronline.org]

• Asthenia

  CASE REPORT A male patient, 37 years old, was admitted with signs of anasarca, progressive muscle weakness, dysphagia to solids, and development of asthenia for 45 days. The patient reported a weight gain of 15 kg during this period. [scielo.br]

There is no single test that can prove diagnosis of polymyositis. Polymyositis is regarded as a diagnosis of exclusion because it affects several organ systems and has different symptoms. A person with polymyositis may also have other myopathy and connective tissue disorders.

Diagnosis of polymyositis is further complicated because its symptoms tend to resemble other myopathies or conditions such as lupus, Cushing syndrome or multiple sclerosis, causing it to become frequently misdiagnosed.

Different and several laboratory tests are used to determine if the patient has polymyositis. Complete blood counts can reveal leukocytosis or thrombocytosis. 50% of polymyositis patients have leukocytosis, positive Rh factor and elevated erythrocyte sedimentation rate (ESR). Myoglobinuria is often present.

Electromyography findings are often used as one of the confirmatory tests for polymyositis. It is used to determine extent of muscle damage in patients with polymyositis. Findings are almost always abnormal, with evidence of membrane irritability, fibrillation potentials, myopathic changes of motor unit action potential, increased polyphasic potentials and bizarre high-frequency repetitive discharges, and evidence of denervation-reinnervation.

Muscle biopsy findings often supports diagnosis of polymyositis, and it helps determine it from other muscle diseases. Electromyography is often first used to determine best sites for muscle biopsies for diagnosis because polymyositis tends to involve patches of muscles. Muscle biopsy findings consistent with polymyositis include presence of inflammation, necrosis and regeneration of muscle fibers, plus focal endomysial infiltration by mononuclear cells; CD8 T lymphocytes and macrophages. Capillary obliteration, endothelial cell damage and increased presence of connective tissue may also be present. In late stage polymyositis, muscle biopsy findings consist of degeneration of muscle cells, fibrosis and presence of regeneration. These findings, along with elevated creatine kinase, confirm the diagnosis of polymyositis.

Patients with polymyositis tend to have elevated serum creatine kinase (CK), usually 5-50 times the reference range. CSK levels greater than 100 times the normal levels are indicative of other conditions. Polymyositis patients may also have elevated lactic dehydrogenase, aspartate aminotransferase and alanine aminotransferase.

Polymyositis patients may exhibit specific antibody findings. Myositis-specific antibodies are often present in patients with polymyositis. Antinuclear antibody assay is also present in one-third of polymyositis cases. Other antibodies that may be present in polymyositis patients include antisynthetase antibodies such as anti-Jo-1 antibodies and Signal-recognition particle (SRP) antibodies.

Imaging studies like magnetic resonance imaging (MRI), chest radiography and high-resolution computerized tomography (CT) is used to determine extent of muscle involvement in patients with polymyositis. MRI is especially useful in scanning muscle inflammation, edema and scarring, and is also used to guide muscle biopsy procedures and monitor disease progression. Chest x-rays and CT scans are used to assess presence of lung disease and possible malignancies.

Patients with diagnosed or suspected polymyositis must be assessed for malignancy. Mammography, pelvic ultrasonography and upper- and lower-endoscopy procedures are used to screen for any associated malignancies.

• Antinuclear Autoantibodies

  Auto-antibodies A variety of auto-antibodies are associated with the disease and include Antinuclear Autoantibodies (ANA), Rheumatoid Factor (RF), and more specific myositis-associated antibodies (e.g. anti-Jo-1, anti-Mi-2, anti-SRP). [pathwaymedicine.org]

• Muscle Biopsy Abnormal

  A diagnosis of classic or definite polymyositis or dermatomyositis (Critieria A and B plus at least one of the three other criteria): Symmetrical proximal muscle weakness; Muscle biopsy abnormalities at some time during their disease: i. degeneration [clinicaltrials.gov]

  Characteristic muscle biopsy abnormalities and the absence of histopathologic signs of other myopathies According to the Bohan and Peter diagnostic criteria for a definite diagnosis of DM it requires four criteria (including rash) and for a definite [e-ijd.org]

There is no exact cure for polymyositis. Cases of polymyositis tend to have different presentations, so the mainstay of treatment is to address the symptoms.

Another reason why treatment is empirical is because only few randomized clinical trials have been conducted to determine best treatment courses for polymyositis.

Since polymyositis is caused by a faulty immune system, drugs that can suppress the activity of the immune system are used for treatment. Corticosteroids like prednisone are used to suppress inflammation to help damaged muscle cells recuperate. High dose is usually maintained for 4 to 8 weeks until creatinine kinase levels go down. Then the dose of prednisone is tapered gradually to minimum therapeutic levels. If effective, the patient may need to take corticosteroids for years. Corticosteroids may not work for everyone, and may cause undesirable adverse effects like changes in personality, swellings of the extremities, acne, cataracts, osteoporosis, diabetes and hypertension.

Immunosuppressants are used to reduce the activity of the nervous system, and they are indicated for cases of polymyositis unresponsive to corticosteroids and for late-stage cases with difficulty in swallowing or speaking. Some examples of immunosuppressants used for polymyositis include azathioprine, cyclophosphamide, methotrexate, chlorambucil, and cyclosporine. Because immunosuppressants can lower down the ability of the immune system to respond against disease-causing pathogens, the patient needs to be protected against infection. Many immunosuppressive drugs also have strong side effects.
Intravenous immunoglobulin and tumor necrosis factor (TNF) has demonstrated efficacy in treatment of refractory cases of polymyositis. Agents like rituximab (anti-CD20 monoclonal antibody) and interferon Alfa-2A are also considered for management of treatment-resistant polymyositis.

Both corticosteroids and immunosuppressants can exert undesirable adverse effects and complications. Therefore, doctors additionally recommend supplementary vitamins and minerals and order frequent lab tests to assess for problems caused by medications.

Plasmapheresis may be used in polymyositis to remove inflammation-causing antibodies in the blood.

Aside from medicines, physical therapy is used for treatment of polymyositis to counter muscle weakness. The goals of physical therapy are to gradually strengthen the muscles and prevent disability. A supervised exercise program may be instituted to improve muscle strength and improve range of motion.

Development of contractures due to muscle weakness may be countered with application of splints. There is a clear need to rehabilitate atrophied muscles after flares ended. Active range-of-motion exercises and isometric contractions can help bring back control on atrophied muscles, and when enough strength has returned, light resistance exercises are then instituted for continued improvement.

Polymyositis can have different prognosis on patients [8]. Some patients only experience brief episodes of muscle weakness followed by a remission that may not require further treatment. Others experience repeated alternating episodes of flares and remissions. But most patients with polymyositis respond to therapy.

Some patients with poor prognosis experience progressive muscle weakness, especially in crucial areas like the heart, chest and throat, causing heart failure, respiratory ammonia, or malnutrition and cachexia.

Polymyositis is caused by an abnormal immune system. In polymyositis, a type of white blood cell called cytotoxic T-cells attack skeletal muscles to cause symptoms. Experts are still unsure how and why T-cells turn and attack healthy and indigenous skeletal muscle cells. According to available evidence, this adverse immune response may be caused by or is associated with viral infections, possible malignancies, autoimmune or connective tissue disorders [4].

Some studies suggests that polymyositis occurs when the T-cells induce a cytotoxic response to some unidentified antigens found in muscle cells. There is also an evidence of autoimmune response to these antigens in muscle cells. It is postulated that these antigens may be a result of an unknown viral infection to the muscle cells, provoking the immune system to attack it. The presence of antibodies specific to these unknown antigens has also been found in some patients. There may be also a genetic link that makes some people predisposed to polymyositis.

Some medical conditions, such as hepatitis B, Coxsackievirus B1, influenza and adenovirus, may increase risk of having polymyositis. Drugs such as hydroxychloroquine and colchicine may also increase risk of metabolic myopathy, though they rarely induce immune-mediated myopathy [5].

Polymyositis is an incredibly rare medical condition. There are only few studies that examined the prevalence of polymyositis. Estimates show that there are only 50 cases of polymyositis for every million people in the United States [2]. In a Quebec-based study, hospital and billing records show that there are only estimated 21.5 polymyositis cases for every 100,000 people [3].
Both polymyositis and dermatomyositis are more commonly seen in females and in adults. Cases of polymyositis are very rare in patients below 18 years of age.

Polymyositis happens when the white blood cells invokes an abnormal immune response that targets skeletal muscle cells, causing progressive inflammation that causes to cellular damage. Normally, white blood cells attack foreign and disease-causing pathogens to protect us from disease. Due to some unknown reason, white blood cells attack the healthy skeletal muscle cells [6].

The resulting damage causes inflammation in the muscle cells that results to atrophy and loss of ability to contract. The patient then experiences symptoms of profound muscle weakness once enough numbers of muscle cells have been affected. Leucocytes affects more and more healthy muscle cells, so more muscle groups becomes weak over time.

Polymyositis always affects the muscles nearest to the trunk first, and then gradually progresses outward until remission occurs.

There are no guidelines for prevention of polymyositis.

Polymyositis is a medical condition wherein the skeletal muscles experiences persistent inflammation that leads to muscular weakness. Polymyositis is somewhat similar to a condition called dermatomyositis, which affects both the skin and muscles. Both conditions are termed as idiopathic inflammatory myopathies [1].
In polymyositis, the leucocytes attacks skeletal muscle cells in the same way it attacks foreign pathogens, causing inflammation that causes the affected muscles to lose muscle tone and thus unable to contract.

Polymyositis tends to produce symmetrical weakness on muscles proximal to the trunk. People with polymyositis experience progressive muscle weakness (or flares), and only few cases experience periods of minimal symptoms (or remission).

Aside from the skeletal muscles, a person with polymyositis may experience other symptoms and have problems to other organs as well. In addition, polymyositis is linked to certain cancers in the ovaries, lung, pancreas, stomach and colon and lymph nodes.
Polymyositis exclusively affects adults, and has a tendency for females rather than males. Polymyositis is a chronic illness, and the bouts of severe muscle weakness can be debilitating at times.

Polymyositis is a medical condition wherein, for unknown reasons, the white blood cells that are supposed to defend the body from disease-causing pathogens attacks normal and healthy muscle cells in the body. Aside from muscle involvement, patients with polymyositis may have other problems in the organs.

Polymyositis belongs to a class of medical conditions called myopathies, and it shares many symptoms with other conditions such as dermatomyositis. And like most myopathies, polymyositis can last for a long period of time. Polymyositis is very rare, and tends to be confined to adults and more common in females.
The exact mechanism on how white blood cells attach normal muscle cells and cause polymyositis is not well understood.

Unknown viral infections, undetected malignancies, disorders in the immune system or connective tissues may make white blood cells turn against muscle cells that cause polymyositis. Regardless of the cause, the white blood cells attack the muscle cells and cause inflammation that results to muscle wasting

A lot of patients with polymyositis also have other conditions including lupus, multiple sclerosis, Cushing syndrome and chronic viral infections like hepatitis B. Polymyositis is also linked to cancers in the ovaries, lungs, colon and lymph nodes and other organs. Therefore, if you have polymyositis you must be regularly screened for presence of cancer.

The main symptom of polymyositis is progressive muscle weakness that spreads outward from the trunk, on both sides of the body. The patient may also experience other symptoms like muscle and joint pains, and kidney problems. The resulting muscle weakness may also make you unable to swallow, speak, move your head or even speak.

Because the symptoms of polymyositis are somewhat same with other conditions, and because it concurrently occurs with other medical conditions, diagnosing is somewhat a challenge. Several different lab tests and imaging studies are required in diagnosis of polymyositis.

The prognosis of polymyositis can vary among patients. Some may only experience brief muscle weakness followed by recovery with no need for more treatment, while others may experience prolonged and progressive muscle weakness plus complications.

1. Choy EHS, Isenberg DA. Treatment of dermatomyositis and polymyositis, Rheumatology. 2002· 41 (1): 7-13.
2. Hill CL, Zhang Y, Sigurgeirsson B, Pukkala E, Mellemkjaer L, Airio A, Evans SR, Felson DT. Frequency of specific cancer types in dermatomyositis and polymyositis: a population-based study, Lancet. 2001; Jan 13;357(9250):96-100.
3. Bernatsky S, Joseph L, Pineau CA, Bélisle P, Boivin JF, Banerjee D, Clarke AE. Estimating the prevalence of polymyositis and dermatomyositis from administrative data: age, sex and regional differences, Ann Rheum Dis; 2009 Jul;68(7):1192-6.
4. Hunter K, Lyon MG. Evaluation and management of polymyositis. Indian J Dermatol. 2012 Sep;57(5):371-4.
5. Aisa Y. et al. Polymyositis, pulmonary fibrosis and malignant lymphoma associated with hepatitis C virus infection. Intern Med. 2001 Nov;40(11):1109-12.
6. Dalakas MC, Hohlfeld R. Polymyositis and dermatomyositis, Lancet 2003; 362: 971-82.
7. Dorph C, Englund P, Nennesmo I, Lundberg IE. Signs of inflammation in both symptomatic and asymptomatic muscles from patients with polymyositis and dermatomyositis. Ann Rheum Dis. 2006 December; 65(12): 1565–1571.
8. Airio A, Kautiainen H, Hakala M. Prognosis and mortality of polymyositis and dermatomyositis patients. Clin Rheumatol. 2006 Mar;25(2):234-9