Myositis – Grade 2

Management escalation pathway

  • Stop ICPI
  • Start corticoids 1mg/kg after discussion with internist/rhumatologist/neuromuscular specialist, continue for at least 1 month even if clinical imporvement after 1 week. If needed add other immunsuppressants so corticoids can be tapered after one month
  • If no improvement after 48h (pain or CK): increase to 2 mg/kg; if still no improvement 48h later, other immunosuppressants should be discussed with experienced organ specialist
  • Consider IVIG (no reimbursment in Belgium) or bolus steroids if severe life threatening weakness, less evidence for plasma exchange

Assessment and Investigations

  • In addition to analysis for grade I:
    • Perform EMG to evaluate myopathic features
    • Assesment of diaphragm motion: X ray and perform respiratory tests both in upright and horizontal position.
  • Perform MRI of affected muscle
  • Consider muscle biopsy before start steroids (should be done by experienced specialist)
  • Analyze serology before start of steroids (ANF (+further subanalysis), myositis specific antibodies / myositis associated antibodies: according to local practice)
  • Perform spirometry in order to assess restrictive syndrom (due to paralysis of intercostal muscles)


ACPA: Anti Citrullinated Antibody
ANF: Anti Nuclear Factor
C3/C4: Complement Factor 3 or 4
CK: Creatine Kinase
CK MB: Creatine Kinase Muscle
ECG: ElectroCardioGram
EMG: ElectroMyoGram
ICPi: Immune Checkpoint Blockade Inhibition
MRI: Magnetic Resonance Imaging
PD: Per Day
PO: Per Os
Pro-BNP: Pro-Brain Natriuretic Peptide
RF: Rheuma Factor
ULN: Upper Limit of Normal