They are dermatomyositis (DM) and polymyositis (PM) and all three illnesses were called idiopathic (of unknown origin) myositis or inflammatory myopathies.It appears that sIBM and polymyositis share some features, especially the initial sequence of immune system activation, however, polymyositis comes on over weeks or months, does not display the subsequent muscle degeneration and protein abnormalities as seen in IBM, and as well, polymyositis tends to respond well to treatments, IBM does not. IBM is often confused with (misdiagnosed as) polymyositis. Polymyositis that does not respond to treatment is likely IBM.Dermatomyositis shares a number of similar physical symptoms and histopathological traits as polymyositis, but exhibits a skin rash not seen in polymyositis or sIBM. It may have different root causes unrelated to either polymyositis or sIBM.Mutations in valosin-containing protein (VCP) cause multisystem proteinopathy (MSP), which can present (among others) as a rare form of inclusion body myopathy. Epidemiology
Prevalence of disease in a rigorous meta-analysis in 2017 was 46 patients per million. The earliest published prevalence was in 2000 and put at 5 per million. A 2017 study in Ireland reported 112 per million. It is not believed that the disease prevalence is increasing with time, but rather diagnostics and reporting are improving.Estimates of the mean age of onset range from 61 to 68 years old. Society and culture
In the biographical drama film Father Stu, the protagonist, a boxer-turned-Catholic priest, has sIBM. See also
Inflammatory myopathies

References
External links
GeneReview/NIH/UW entry on Inclusion Body Myopathy 2
Complications
Potential complications include:
obstruction of the epididymis
impairment of spermatogenesis
impairmentment of sperm function
induction of sperm auto-antibodies
dysfunctions of the male accessory glandsThese complications can result in
sexual dysfunction and male subfertility. References


== External links ==