AchR-positive myasthenia gravis with MRI evidence of early muscle atrophy.

Muscle atrophy, when it occurs in myasthenia gravis (MG), is usually associated with long-standing disease or with chronic corticosteroid treatment. Early muscle atrophy in a steroid-naive patient has been reported previously only in muscle-specific tyrosine kinase (MuSK)-MG. We report a 63-year-old male patient with acetylcholine receptor (AchR)-positive MG with a short duration of disease, no steroid treatment and MRI evidence of muscle atrophy.