Polymyositis: Symptoms, Pathogenesis, Diagnosis & Treatments
Symptoms
Polymyositis is one of the idiopathic inflammatory myopathies characterized by proximal muscle weakness and muscle inflammation. Polymyositis is caused by cell mediated immunity due to endomysial infiltration of T cells, and thus an immune response is produced by CD8 + T cells. Clinical manifestations may vary depending on which autoantibody is involved in the disease and in which environment. The most common symptom is proximal muscle weakness or associated myalgia and muscle tenderness, as well as interstitial pulmonary disease (more frequently when anti-synthetase Ab is present), dysphagia due to esophageal muscle weakness, polyarthritis, Raynaud phenomenon symptoms May appear. Sometimes systemic sclerosis or systemic rheumatic disease features such as systemic lupus erythematosus are combined. Polymyositis is less common than dermatomyositis, but it also increases the risk of malignancy. When combined with anti-synthetase syndrome, a palmar of the finger, a mechanical hand with hyperkeratotic and fissured skin on the lateral part is characteristic. Concomitant cardiac disease is also reported.
Pathogenesis
Anti-synthetase antibodies such as anti Jo-1, anti-SRP, and anti-Mi-2 are among the autoantibodies involved in polymyositis. Anti-synthetase antibody is the most common autoantibody in myositis. Anti-Jo-1 targets histidyl tRNA synthetase and causes major clinical manifestations in anti-synthetase syndrome. Anti-SRP is involved in the mechanism of transferring newly produced proteins to the endoplasmic reticulum, which is mainly found in patients with Polymyositis. Muscle fiber necrosis and endomysial fibrosis appear similar to other patients with the same disease but no inflammatory cell infiltration occurs in muscle biopsy of the patient. Anti-Mi-2 is involved in helicase 2, which induces transcriptional activation, but is known to be more associated with dermatomyositis than polymyositis. In addition, autoantibodies such as anti hPMS-1, anti MDA-5, and anti p140 can cause polymyositis.
Diagnosis
First, the diagnosis of polymyositis is made by history taking of clinical symptoms of muscle weakness, dyspnea due to dysphagia and dyspnea due to ILD, and physical examination of joint, skin and muscle for accurate diagnosis. Lab testing confirms the elevation of muscle enzymes such as CK, aldolase, and lactate dehydrogenase, and identifies serum levels of autoantibodies, such as anti Jo-1, that are readily identified in ANA titer and polymyositis. Imaging is performed by using chest X-ray or CT to detect interstitial lung disease associated with polymyositis, and NCV / EMG test to confirm Muscle origin weakness. MRI may be considered to confirm atrophy and inflammatory findings of Muscle. The final diagnosis is made by confirming histologic findings of typical polymyositis through muscle biopsy.
Treatments
Treatment of polymyositis is aimed at resolving muscle recovery and extramuscular complications. For this, systemic glucocorticoids, azathioprine, and metotrexate may be used. If this is not effective, intravenous immunoglobulin, rituximab, mycophenolate motefil, cyclosporine, tacrolimus, cyclophosphamide, etc. may be tried.
Polymyositis is one of the idiopathic inflammatory myopathies characterized by proximal muscle weakness and muscle inflammation. Polymyositis is caused by cell mediated immunity due to endomysial infiltration of T cells, and thus an immune response is produced by CD8 + T cells. Clinical manifestations may vary depending on which autoantibody is involved in the disease and in which environment. The most common symptom is proximal muscle weakness or associated myalgia and muscle tenderness, as well as interstitial pulmonary disease (more frequently when anti-synthetase Ab is present), dysphagia due to esophageal muscle weakness, polyarthritis, Raynaud phenomenon symptoms May appear. Sometimes systemic sclerosis or systemic rheumatic disease features such as systemic lupus erythematosus are combined. Polymyositis is less common than dermatomyositis, but it also increases the risk of malignancy. When combined with anti-synthetase syndrome, a palmar of the finger, a mechanical hand with hyperkeratotic and fissured skin on the lateral part is characteristic. Concomitant cardiac disease is also reported.
Pathogenesis
Anti-synthetase antibodies such as anti Jo-1, anti-SRP, and anti-Mi-2 are among the autoantibodies involved in polymyositis. Anti-synthetase antibody is the most common autoantibody in myositis. Anti-Jo-1 targets histidyl tRNA synthetase and causes major clinical manifestations in anti-synthetase syndrome. Anti-SRP is involved in the mechanism of transferring newly produced proteins to the endoplasmic reticulum, which is mainly found in patients with Polymyositis. Muscle fiber necrosis and endomysial fibrosis appear similar to other patients with the same disease but no inflammatory cell infiltration occurs in muscle biopsy of the patient. Anti-Mi-2 is involved in helicase 2, which induces transcriptional activation, but is known to be more associated with dermatomyositis than polymyositis. In addition, autoantibodies such as anti hPMS-1, anti MDA-5, and anti p140 can cause polymyositis.
Diagnosis
First, the diagnosis of polymyositis is made by history taking of clinical symptoms of muscle weakness, dyspnea due to dysphagia and dyspnea due to ILD, and physical examination of joint, skin and muscle for accurate diagnosis. Lab testing confirms the elevation of muscle enzymes such as CK, aldolase, and lactate dehydrogenase, and identifies serum levels of autoantibodies, such as anti Jo-1, that are readily identified in ANA titer and polymyositis. Imaging is performed by using chest X-ray or CT to detect interstitial lung disease associated with polymyositis, and NCV / EMG test to confirm Muscle origin weakness. MRI may be considered to confirm atrophy and inflammatory findings of Muscle. The final diagnosis is made by confirming histologic findings of typical polymyositis through muscle biopsy.
Treatments
Treatment of polymyositis is aimed at resolving muscle recovery and extramuscular complications. For this, systemic glucocorticoids, azathioprine, and metotrexate may be used. If this is not effective, intravenous immunoglobulin, rituximab, mycophenolate motefil, cyclosporine, tacrolimus, cyclophosphamide, etc. may be tried.
