A study conducted by a hospital in Beijing (China) has refined our knowledge of the phenotype of immune-mediated necrotising myopathy in paediatrics:
- 55 of the 116 children and adolescents followed up for myositis by this centre between 2012 and 2024 had immune-mediated necrotising myopathy, a much higher proportion (47.4%) than expected, but one that would be specific to the Chinese population,
- the onset of the disease varied widely in age (between one and 17 years), but was more often chronic (lasting six months or more), with muscle weakness in the limbs or asymptomatic hyperCKaemia,
- anti-HMGCR autoantibodies are present in 61.8% of cases, and anti-SRP in 20%,
- The most frequent symptoms are proximal and cervical muscle damage,
- MRI of the thighs showed muscle oedema and fatty infiltration proportional to the duration of the disease.
A follow-up study involving 39 of the patients in this cohort highlighted the difficulties of treatment: an equal proportion (46.2%) of patients experienced relapses or remissions after high-dose corticosteroid therapy and multiple lines of immunosuppressants.
