The hallmark of polymyositis is weakness and/or loss of muscle mass in the proximal musculature, as well as flexion of the neck and torso.[1] These symptoms can be associated with marked pain in these areas as well. The hip extensors are often severely affected, leading to particular difficulty in climbing stairs and rising from a seated position. The skin involvement of dermatomyositis is absent in polymyositis. Dysphagia (difficulty swallowing) or other problems with esophagealmotility occur in as many as 1/3 of patients. Low grade fever and enlarged lymph nodes may be present. Foot drop in one or both feet can be a symptom of advanced polymyositis and inclusion body myositis. The systemic involvement of polymyositis includes interstitial lung disease (ILD) and heart disease, such as heart failure and conduction abnormalities.[2]
Polymyositis tends to become evident in adulthood, presenting with bilateral proximal muscle weakness often noted in the upper legs due to early fatigue while walking. Sometimes the weakness presents itself as an inability to rise from a seated position without help or an inability to raise one's arms above one's head. The weakness is generally progressive, accompanied by lymphocytic inflammation (mainly cytotoxic T cells).[citation needed]
Cardiac involvement manifests itself typically as heart failure and is present in up to 77% of patients.[2]
Interstitial lung disease is found in up to 65% of patients with polymyositis, as defined by HRCT or restrictive ventilatory defects compatible with interstitial lung disease.[5]
Polymyositis is an inflammatory myopathy mediated by cytotoxic T cells with an as yet unknown autoantigen, while dermatomyositis is a humorally mediated angiopathy resulting in myositis and a typical dermatitis.[6]
The cause of polymyositis is unknown and may involve viruses and autoimmune factors. Cancer may trigger polymyositis and dermatomyositis, possibly through an immune reaction against cancer that also attacks a component of muscles.[7] There is tentative evidence of an association with celiac disease.[8]
The hallmark clinical feature of polymyositis is proximal muscle weakness, with less important findings being muscle pain and dysphagia. Cardiac and pulmonary findings will be present in approximately 25% of cases of patients with polymyositis.[citation needed]
Sporadic inclusion body myositis (sIBM) is often misdiagnosed as polymyositis or dermatomyositis but it can be differentiated as myositis that does not respond to treatment is likely IBM. sIBM comes on over months to years; polymyositis comes on over weeks to months. Polymyositis tends to respond well to treatment, at least initially; IBM does not.[citation needed]
The discovery of several myositis-specific autoantibodies during the past decades has enabled the description of other discrete subsets of diagnosis, specifically the discovery of Antisynthetase syndrome in reducing the number of diagnoses of polymyositis.[12]
Robert Erickson, American composer and teacher who was a leading modernist exponent of "12-tone" composition. Died from the effects of polymyositis.[14]
Ana Estrada, the first person in Peru to die by euthanasia on 21 April 2024, at the age of 47.
^Leclair, Valérie; Notarnicola, Antonella; Vencovsky, Jiri; Lundberg, Ingrid E. (November 2021). "Polymyositis: does it really exist as a distinct clinical subset?". Current Opinion in Rheumatology. 33 (6): 537–543. doi:10.1097/BOR.0000000000000837. PMID34494607. S2CID237443416.
^Stevens, George Jr. (2006). Conversations with the Great Moviemakers of Hollywood's Golden Age at the American Film Institute. Knopf. p. 427. ISBN978-1-4000-4054-4.
