Updated: 11/21/2020

Dermatomyositis / Polymyositis

0%
Topic
Review Topic
0
0
N/A
N/A
Questions
7 7
0
0
0%
0%
Evidence
3 3
0
0
Snapshot
  • A 49-year-old woman with polymyositis presents to her physician’s office for weakness. She reports that she feels unusually tired and weak. She works as a makeup artist and in the past few weeks has experienced difficulty applying makeup on her clients. She finds it difficult to work while she has her arms raised. She denies any fevers, weight gain or loss, or any other motor deficits. Physical exam reveals decreased strength in her shoulders. No rash is appreciated. Laboratory evaluation reveals increased creatinine phosphokinase, positive antinuclear antibody, and positive anti-signal recognition particle. She is started on high-dose corticosteroids. (Polymyositis)
Introduction
  • Clinical definition
    • dermatomyositis is an autoimmune myopathy characterized by
      • symmetric proximal muscle weakness and rash
        • the clinical variant includes amyopathic dermatomyositis (dermatomyositis without myositis)
    • polymyositis is an autoimmune myopathy characterized by
      • symmetric proximal muscle weakness and no rash
  • Epidemiology
    • demographics
      • female > male
      • typically in adults 30-50 years of age
      • if in children, considered juvenile dermatomyositis
    • risk factors
      • drugs
      • physical exertion
  • Pathogenesis
    • dermatomyositis
      • an antibody-driven autoimmune disease characterized by perimysial inflammation and atrophy, resulting in muscle tissue damage
        • perimysium is closer to the skin and therefore has cutaneous manifestations – “dermato”
      • associated with CD4+ lymphocytes and complement activation
    • polymyositis
      • T-cell driven autoimmune disease characterized by endomysial inflammation
        • endomysium is farther from the skin and therefore has no cutaneous manifestations
      • associated with CD8+ lymphocytes
  • Associated conditions
    • interstitial lung disease
    • malignancy including
      • breast or ovarian cancer
      • prostate cancer
      • lung cancer
    • other connective tissue diseases
  • Prognosis
    • dermatomyositis
      • ↑ risk of malignancy (typically develops within 5 years of diagnosis)
Presentation
  • Symptoms
    • progressive weakness in hips and shoulders
    • dysphagia
    • dysphonia
      • laryngeal muscle weakness
  • Physical exam
    • dermatomyositis
      • characteristic cutaneous findings
        • a photosensitive pink rash of the neck and trunk
          • shawl or V-sign, as it often appears as sunburn with V-neck t-shirt
        • purple/lilac or red rash around eyes and on eyelids (heliotrope rash)  
          • can resemble a malar rash
        • raised violaceous, slightly scaly plaques, on bony prominences of the hands and elbows (Gottron papules) 
          • “mechanic’s hands” 
    • polymyositis and dermatomyositis
      • proximal muscle weakness in the shoulders and hips
        • difficulty combing hair
        • difficulty raising arms
        • difficulty rising from a chair
Studies
  • Labs
    • ↑ creatinine phosphokinase (CPK or CK)
    • ↑ creatine kinase-MB (CK-MB)
    • ↑ aldolase
    • ↑ lactate dehydrogenase (LDH)
    • autoantibodies 
      • + antinuclear antibody (ANA)
      • + anti-Jo-1 (~20% of patients)
      • + anti-signal recognition particle (SRP) (~5% of patients)
        • usually associated with polymyositis
      • + anti-Mi-2 (<10% of adults)
        • usually associated with dermatomyositis
  • Muscle biopsy   
    • indication
      • diagnostic gold standard to differentiate between inflammatory and non-inflammatory myopathies
    • findings
      • degenerating muscle fibers and inflammatory infiltrates
      • dermatomyositis
        • perimysial inflammation
      • polymyositis
        • endomysial inflammation 
  • Making the diagnosis
    • based on clinical presentation and laboratory studies
Differential
  • Systemic lupus erythematosus
  • Localized scleroderma
  • Infectious myopathy
  • Myasthenia gravis
  • Inclusion body myositis 
    • presents with weakness and elevated CRP/CK
    • biopsy demonstrates endomysial inflammation with basophilic-rimmed vacuoles
Treatment
  • Management approach
    • both diseases are often treated initially with a course of steroids, followed by long-term immunosuppression
  • Conservative
    • sun protection
      • indication
        • for all patients with dermatomyositis
  • Medical
    • systemic steroids (high-dose) 
      • indications
        • for all patients with myositis as first-line therapy 
        • 2-4 weeks with subsequent taper
    • antimalarial
      • indications
        • for patients with primarily skin manifestations of dermatomyositis
        • drugs
          • hydroxychloroquine
    • non-steroidal immunosuppression
      • indications
        • for refractory disease
        • for prevention of recurrence after steroid taper
        • drugs
          • methotrexate
          • azathioprine
Complications
  • Cardiomyopathy
  • Macrophage activation syndrome
 

Please rate topic.

Average 5.0 of 5 Ratings

Questions (7)
Question locked
Sorry, this question is for
PEAK Premium Subscribers only
Upgrade to PEAK
Question locked
Sorry, this question is for
PEAK Premium Subscribers only
Upgrade to PEAK
Question locked
Sorry, this question is for
PEAK Premium Subscribers only
Upgrade to PEAK

(M2.RH.17.4727) A 48-year-old Caucasian female presents to her primary care physician for evaluation of progressive weakness and shortness of breath. She has had progressive shortness of breath over the last year with an intermittent non-productive cough. In addition, she complains of difficulty raising her arms to brush her hair. Her temperature is 99.6°F (37.6°C), pulse is 80/min, blood pressure is 130/85 mmHg, respirations are 18/min, and oxygen saturation is 95% on room air. Neurologic exam shows 4/5 strength in the deltoid muscles bilaterally. Diffuse dry crackles are heard on lung auscultation. A faint erythematous rash is noted on the malar cheeks, periorbital areas, lateral proximal thighs, and the elbows. Which of the following tests is most likely to confirm the diagnosis? Tested Concept

QID: 108589
1

Muscle biopsy

81%

(17/21)

2

CT scan

0%

(0/21)

3

Pulmonary function tests

0%

(0/21)

4

Serum ANA titer

5%

(1/21)

5

Skin biopsy

14%

(3/21)

M 6 D

Select Answer to see Preferred Response

(M3.RH.16.12) A 39-year-old woman comes into your office with multiple complaints of recent onset. She has been feeling fatigued and has started having leg and thigh pain bilaterally, along with weakness. In addition, she states that she recently started noticing some redness around her eyes along with a rash on her shoulders as shown in Figure A. Of note, she takes simvastatin for her hyperlipidemia, and took a short course of steroids recently for an allergic reaction. Her vitals are within normal limits. Her CK is 400 U/L, ESR is 70 mm/hr, and ferritin is 500 mcg/L. What is the most likely diagnosis? Tested Concept

QID: 102766
FIGURES:
1

Inclusion body myositis

0%

(0/2)

2

Corticosteroid induced myopathy

0%

(0/2)

3

Statin induced myopathy

0%

(0/2)

4

Dermatomyositis

100%

(2/2)

5

Polymyositis

0%

(0/2)

M 10 C

Select Answer to see Preferred Response

(M3.RH.15.70) A 40-year-old woman presents to her primary care physician with complaints of worsening muscle aches and diffuse weakness over the past several months. She states that she now has difficulty climbing stairs and extending her neck. Ultimately, she became more concerned when she began having trouble swallowing and experienced shortness of breath last night which has resolved. Her temperature is 98.5°F (36.9°C), blood pressure is 120/84 mmHg, pulse is 70/min, respirations are 12/min, and oxygen saturation is 98% on room air. Physical exam is notable for 2/5 strength of the proximal muscles of the upper and lower extremities. Dermatologic, cardiac, and pulmonary exam are unremarkable. The patient is tolerating oral secretions and has no difficulty swallowing or protecting her airway currently. Laboratory studies are notable for an elevated CRP and aldolase. Which of the following is the most appropriate treatment for this patient? Tested Concept

QID: 103011
1

Intravenous immunoglobulin

0%

(0/3)

2

Methotrexate

0%

(0/3)

3

Naproxen

100%

(3/3)

4

Neostigmine

0%

(0/3)

5

Prednisone

0%

(0/3)

M 11 E

Select Answer to see Preferred Response

Question locked
Sorry, this question is for
PEAK Premium Subscribers only
Upgrade to PEAK
Evidence (3)
Topic COMMENTS (17)
Private Note