Dermatomyositis
Background
- Inflammatory myopathy with skin manifestations
- Affects proximal muscles > distal
- Female:Male; 2:1
- Peak incidence 40-50s
- Juvenille dermatomyositis: 5-10 years of age
Clinical Features
Muscular
- Symmetric weakness
- Proximal greater than distal weakness
- Deltoid and hip flexors
- difficulty standing from a chair
- Onset over months
- Mild myalgias
- Dysphagia due to esophageal muscle dysfunction
- GERD due to smooth muscle inflammation, gastric ulcer disease
- Thoracic muscle weakness
Dermatologic
- Heliotrope rash on face scalp
- Periorbital edema
- Gottron's papules (rash on MCP, PIP, and DIP joints)
- Shawl sign (rash above shoulders)
- Pruritus
- Calcinosis
- Nodules over joints can lead to debilitating contractures, especially in children
Respiratory
- Respiratory manifestations associated with presence of anti-Jo1 antibody[1]
- Increased risk of aspiration, which is a leading cause of death in patients with restricted mobility[2]
- Poor prognosis
- Interstitial lung disease
- Thoracic muscle weakness
Cardiac
- Dilated cardiomyopathy
- Cardiac myositis
- Suspect in known dermatomyositis with mild rhythm disturbances, CHF or myocardial fibrosis
- Causes include reentry pathways, fibrosis, altered automaticity, conduction system injury or treatment side effects
Other
Differential Diagnosis
Myalgia
- Infection:
- Viral infection (e.g. Influenza)
- Bacterial infection
- Spirochete infection (E.g. Dengue fever; Trichinella)
- Drugs:
- Statins
- Bisphosphonates
- Corticosteroids
- Ciprofloxacin
- Clofibrate
- Colchicine
- Chloroquine
- Emetine
- Aminocaproic acid
- Zidovudine
- Bretylium
- Penicillamine
- Drugs causing hypokalemia
- Metabolic disorders:
- Vitamin D deficiency
- Mitochondrial myopathy
- Scurvy
- Osteomalacia
- Fibromyalgia
- Endocrine:
- Polymyalgia rheumatica
- Rhabdomyolysis
- Myositis
- Systemic lupus erythematosus
- Rheumatoid arthritis
- Inclusion body myositis
- Sarcoidosis
- Scleroderma
- Sjögren’s syndrome
- Psychiatric (e.g. somatic manifestations of depression)
- Domestic abuse
- Crush injury
- Lyme disease
- Ehlers-Danlos syndrome(hypermobility syndrome)
- HIV myopathy
- Hypophosphatemia
- Hypokalemia
- Hypothermia
- Prolonged immobility
- Strenuous exercise (overuse) or heat stroke
- Seizure
- Severe volume contraction
- Alcoholism
- Muscular dystrophy
- Duchenne
- Becker
- Limb-girdle
- Facioscapulohumeral
- Myotonic dystrophy
- Myotonia congenita
- Compartment syndrome; Muscle infarction
- Neuropathic
- Chronic fatigue syndrome
- Vasculitis
- Sarcocystosis
- Spinal stenosis
- Diabetic lumbosacral plexopathy
Weakness
- Neuromuscular weakness
- Upper motor neuron:
- CVA
- Hemorrhagic stroke
- Multiple sclerosis
- Amyotrophic Lateral Sclerosis (ALS) (upper and lower motor neuron)
- Lower motor neuron:
- Spinal and bulbar muscular atrophy (Kennedy's syndrome)
- Spinal cord disease:
- Infection (Epidural abscess)
- Infarction/ischemia
- Trauma (Spinal Cord Syndromes)
- Inflammation (Transverse Myelitis)
- Degenerative (Spinal muscular atrophy)
- Tumor
- Peripheral nerve disease:
- Neuromuscular junction disease:
- Muscle disease:
- Rhabdomyolysis
- Dermatomyositis
- Polymyositis
- Alcoholic myopathy
- Upper motor neuron:
- Non-neuromuscular weakness
- Can't miss diagnoses:
- ACS
- Arrhythmia/Syncope
- Severe infection/Sepsis
- Hypoglycemia
- Periodic paralysis (electrolyte disturbance, K, Mg, Ca)
- Respiratory failure
- Emergent Diagnoses:
- Symptomatic Anemia
- Severe dehydration
- Hypothyroidism
- Polypharmacy
- Malignancy
- Aortic disease - occlusion, stenosis, dissection
- Other causes of weakness and paralysis
- Acute intermittent porphyria (ascending weakness)
- Can't miss diagnoses:
Evaluation
Workup
- Evaluate for emergent complications (e.g. respiratory distress, cardiomyopathy, arrhythmia)
- BMP
- ECG, troponin to screen for myocardial involvement
- CK, Urinalysis for myoglobin
- Signs of systemic inflammation[3]
- ESR elevated in 50% of patients, does not correlate with disease activity
- Elevated CRP
Non-ED Evaluation
- ANA, Anti-Jo-1, myositis antibody panel
- Bedside PFTs (FEV1 and FVC)
- EMG or muscle biopsy showing myositis
- Malignancy screening/evaluation
- Increased risk of malignancy (~30%), especially:[4] ovarian, lung, pancreatic, stomach, colorectal, bladder, and non-hodgkin lymphoma
- Associated with increased age, male gender and elevated creatinine kinase levels
Management
Mild disease
- Prednisone 1mg/kg/day (up to 80mg/day)
- Taper after 6-8 weeks
Severe disease
- Interstitial fibrosis or weakness of respiratory muscles
- Methylprednisolone 1000mg/day x 3 days
- Methotrexate or azathioprine for cases refractory to steroids
Outpatient
- Sunscreen!
- Hydroxychloroquine
- Other immunosuppressive meds (e.g. methotrexate, rituximab, azathioprine)
- Calcium channel blockers for calcinosis
Disposition
- Admit for decompensated respiratory, cardiac, or other major disease
See Also
References
- ↑ Vymetal J, Skacelova M, Smrzova A, Klicova A, Schubertova M, Horak P, Zadrazil J. Emergency situations in rheumatology with a focus on systemic autoimmune diseases. Biomed Pap Med Fac Univ Palacky Olomouc Czech Repub. 2016 Mar;160(1):20-9. doi: 10.5507/bp.2016.002. Epub 2016 Feb 10. Review. PubMed PMID: 26868300.
- ↑ Fujisawa T, Hozumi H, Kono M, Enomoto N, Hashimoto D, Nakamura Y, Inui N, Yokomura K, Koshimizu N, Toyoshima M, Shirai T, Yasuda K, Hayakawa H, Suda T. Prognostic factors for myositis-associated interstitial lung disease. PLoS One [serial on the internet] 2014 Jun [cited 2014 Oct 20]; Available from: http://www.ncbi.nlm.nih.gov/ pmc/articles/PMC4048238/?report=classic
- ↑ Koler RA and Montemarano A. Dermatomyositis. Am Fam Physician. 2001 Nov 1;64(9):1565-1573.
- ↑ Hill CL et al. Frequency of specific cancer types in dermatomyositis and polymyositis: a population-based study. Lancet. 2001 Jan 13;357(9250):96-100.