Polymyositis: Or something else? Differential Diagnosis

Endocrine, nutritional, and metabolic diseases (E00-E90).

Musculoskeletal system and connective tissue (M00-M99).

  • Inclusion body myositis – neuromuscular disease; weakness near the trunk, fewer atrophies.
  • Muscular dystrophies (muscle atrophy).
  • Myositides (muscle inflammation), infectious origin (Coxsackie viruses, trichinosis, HIV).
  • Polymyalgia rheumatica – inflammatory rheumatic disease belonging to the vasculitides (vascular inflammation); pain and stiffness sensation in the shoulder/pelvic girdle.
  • Sharp syndrome (“mixed connective tissue disease”, MCTD) – chronic inflammatory connective tissue disease that includes symptoms of several collagenoses such as lupus erythematosus, scleroderma, or polymyositis
  • Scleroderma – belongs to the group of autoimmune connective tissue diseases (collagenoses).
  • Systemic lupus erythematosus (SLE) – systemic disease affecting the skin and connective tissue of the vessels, leading to vascular inflammation (vasculitides) of numerous organs such as the heart, kidneys or brain.

Psyche – Nervous System (F00-F99; G00-G99).

  • Alcohol myopathy (alcohol-related muscle disease).
  • Amyotrophic lateral sclerosis (ALS) – progressive (progressive), irreversible degeneration of the motor nervous system (rare).
  • Lambert-Eaton syndrome – autoimmune disease leading to muscle weakness and reflex loss.
  • Myasthenia gravis – rare autoimmune disorder in which specific antibodies to acetylcholine receptors are present, resulting in load-dependent muscle weakness of voluntary motor function leading to recovery at rest; sometimes the symptomatology consists only of increased fatigability of ocular muscles (ocular myasthenia)

Medications

Inflammatory myopathies

  • Allopurinol (urostatic drug/for the treatment of elevated uric acid levels).
  • Antimalarials such as chloroquine
  • D-penicillamine (antibiotic)
  • Interferon alpha (antiviral and antitumor effects).
  • Cocaine
  • Levodopa
  • Procainamide (local anesthetic)
  • Simvastatin (statins; lipid-lowering drugs)
  • Sulfonamides
  • Zidovudine

Other myopathies

  • ACTH
  • Antiviral drugs
  • Carbimazole
  • Clofibrate
  • Cromoglicic acid
  • Cyclosporine
  • Enalapril
  • Ezetimibe
  • Hormones
    • ACTH
    • Corticosteroids
  • HMG-CoA reductase inhibitors (hydroxy-methyl-glutaryl-coenzyme A reductase inhibitors; Statins) – atorvastatin, cerivastatin, fluvastatin, lovastatin, mevastatin, pitavastatin, pravastatin, rosuvastatin, simvastatin) more commonly cause rhabdomyolysis (dissolution of striated muscle fibers/skeletal muscle as well as cardiac muscle) in combination with fibrates, ciclosporin (cyclosporin A), macrolides, or azole antifungals; Furthermore, statins lead to a decrease in endogenous coenzyme Q10 synthesis; frequency of myalgia in clinical practice is 10% to 20%The term statin myopathy is used when:
    • Symptoms occur within four weeks of starting statin use
    • They remit within four weeks after discontinuation of the drug, and
    • Recur upon re-exposure.
  • Metoprolol
  • Minoxidil
  • Proton pump inhibitors (PPI; acid blockers) – esomeprazole, lansoprazole, omeprazole, pantoprazole, rabeprazole.
  • Salbutamol

Myopathy and neuropathy

  • Amiodarone
  • Colchicine
  • Interferon
  • L-tryptophan
  • Vincristine