Table 1 Main differential diagnosis of idiopathic myositis
From: Muscle biopsy features of idiopathic inflammatory myopathies and differential diagnosis
Muscular dystrophies | Metabolic myopathies |
Facioscapulohumeral dystrophy (FSHD) | Myophosphorylase deficiency |
Dysferlinopathies (LGMD2B, Miyoshi type) | Adult-onset acid maltase deficiency |
Congenital dystrophies (merosin deficiency) | Lipid storage myopathies |
Dystrophinopathies (Becker) | Carnitine deficiency |
Mitochondrial myopathies | |
Endocrine myopathies | Toxic/drug-induced myopathies |
Hypercorticosurrenalism | Statin-induced myopathies |
Hyper/hypothyroidism | Antiretroviral drug myopathy |
Hyper/hypoparathyroidism | Steroid myopathy |
Others: antibiotics, chinidine, D-penicillamine, procainamide, FANS, TNF and H+ pump inhibitors | |
Non-muscular diseases | Systemic disorder-associated myopathies |
Guillain–Barrè syndrome | Nutritional deficits associated myopathy (alcoholism, malabsorption) |
Transverse myelitis | Electrolyte imbalance myopathies (hypophosphatemia, hypomagnesemia, hypokalemia) |
Neuromuscular junction pathology (myasthenia gravis, Lambert–Eaton syndrome) | Critical illness myopathy (CIM) |
Rheumatic diseases, fibromyalgia | Cancer-associated myopathies (disuse, cachexia, drug-induced, paraneoplastic neuromyopathy) |
Periodic paralysis |