Editing Inclusion body myositis (section)

==Other related disorders==
When sIBM was originally described, the major feature noted was muscle inflammation. Two other disorders were also known to display muscle inflammation, and sIBM was classified along with them. They are [[dermatomyositis]] (DM) and [[polymyositis]] (PM) and all three illnesses were called [[idiopathic]] (of unknown origin) myositis or inflammatory myopathies.<ref>{{cite web |url=https://www.lecturio.com/concepts/dermatomyositis-dm/| title=Dermatomyositis (DM)
|website=The Lecturio Medical Concept Library |access-date= 11 July 2021}}</ref>

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.<ref>[http://www.myositis.org/your-myositis-community/live-discussions/406-when-myositis-doesnt-respond-to-treatment When myositis doesn't respond to treatment] Retrieved 20 April 2015.</ref>

[[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.<ref>{{Cite journal |last1=Malik |first1=Asma |last2=Hayat |first2=Ghazala |last3=Kalia |first3=Junaid S. |last4=Guzman |first4=Miguel A. |date=2016-05-20 |title=Idiopathic Inflammatory Myopathies: Clinical Approach and Management |journal=Frontiers in Neurology |language=en |volume=7 |page=64 |doi=10.3389/fneur.2016.00064 |pmid=27242652 |pmc=4873503 |issn=1664-2295|doi-access=free }}</ref>

Mutations in [[valosin-containing protein]] (VCP) cause [[multisystem proteinopathy]] (MSP), which can present (among others) as a rare form of inclusion body myopathy.<ref>{{cite journal |vauthors=Harrison AF, Shorter J |title=RNA-binding proteins with prion-like domains in health and disease |journal=Biochem. J. |volume=474 |issue=8 |pages=1417–1438 |date=April 2017 |pmid=28389532 |pmc=5639257 |doi=10.1042/BCJ20160499 }}</ref>