21 September marks World Myositis Day

Also known as ‘inflammatory myopathies’, myositis is linked to inflammationRéaction non spécifique suscitée par un agent pathogène. of an autoimmune origin: it results from a malfunction of the immune system that leads to the production of pathological antibodies (autoantibodies), causing damage to tissues (muscles, skin, lungs, heart, etc.).

Myositis can affect both adults and children. It causes weakness, muscle wasting, fatigue and, in some cases, damage to the skin, heart and lungs. There are various forms (dermatomyositis, inclusion body myositis, etc.), which differ in their underlying mechanisms and symptoms. A wide range of medicines is already available to treat these conditions, but research continues with the aim of advancing our understanding and further improving patient care.

Under the current classification, five main forms of inflammatory myopathy are currently associated with myositis-specific autoantibodies (MSA):

• dermatomyositis, which can also affect children (juvenile dermatomyositis) and is additionally characterised by skin involvement,
• inclusion body myositis,
• antisynthetase syndrome,
• immune-mediated necrotising myopathy,
• myositis overlapping with other autoimmune diseases,

The existence of polymyositis is a matter of debate, with most patients being reclassified into one of the five categories above).

This classification and the criteria used to diagnose each type of myositis have evolved over the years, in line with advances in our understanding.