Myositis is a collection of several rare diseases that share the common elements of muscle weakness and/or pain along with an autoimmune component. In adults, these diseases include polymyositis (PM), dermatomyositis (DM), necrotizing myopathy (NM) and sporadic inclusion body myositis (sIBM). There is also a juvenile form of DM that affects children (JDM). Myositis signs and symptoms include: muscles weakness, sometimes with muscle pain; general tiredness and fatigue; trouble climbing stairs, standing from a seated position or reaching up; difficulty swallowing or breathing; rash on knuckles, chest, face, and back; persistent dry cough.
20% of CSI Pharmacy patients have a form of myositis.