Inclusion myositis (or IBM for Inclusion body myositis) belongs to the group of inflammatory myopathies of autoimmune origin. US researchers from the Mayo Clinic compiled data from 357 patients diagnosed with IBM between 2015 and 2022 :
- 14% of patients had clinically atypical forms of the disease,
- These included isolated swallowing disorders (50%), isolated and chronic elevation of CPK levels (24%), deficit of one or more foot elevators (12%), proximal upper extremity deficit (6%), or facial diplegia (4%),
- 56% of patients had positive autoantibodies to cytosolic nucleotidase-1A,
- only one patient had a partial response to immunosuppressive therapy.
A greater awareness of these atypical presentations may reduce diagnostic error.
