Polymyositis and Dermatomyositis

Question 1

What is Polymyositis and Dermatomyositis?

Answer 1

Idiopathic inflammatory myopathies
Symmetrical, proximal muscle weakness

Other types
Myositits syndromes
Assoc with CA and seen in pts > 50 y/o

Question 2

What is associated with Polymyositis and Dermatomyositis?

Answer 2

Myositits syndromes

• Associated with cancer
• Pts > 50 y/o

Question 3

What is the epidemiology of Polymyositis and Dermatomyositis?

Answer 3

Peak:

• 7-15 yrs (Dermatomyositis)
• 30-50 yrs

3:1 F:M

Higher risk in african americans

Question 4

What is the pathophysiology of Polymyositis and Dermatomyositis?

Answer 4

Chronic immune activation after exposure to trigger
- Environmental

Focal collection of mononuclear cells -> muscle necrosis

Polymyositis

• Cytotoxic T lymphocyte- mediated process
• CD8+ T cells

Dermatomyositis

• B lymphocytes
• Dendritic cells
• CD4+ helper T cells

Autoantibodies are also found

Question 5

What are the environmental triggers of Polymyositis and Dermatomyositis?

Answer 5

Viral and bacterial infections
Drugs
Cytokines
Dietary supplements
Medical implants
Occupations exposures

Question 6

What is the clinical presentation of Polymyositis and Dermatomyositis?

Answer 6

Symmetrical, proximal muscle weakness
Difficulty raising from sitting or getting out of car
Reaching overhead or combing hair
Generalize fatigue or muscle pain

Question 7

What is the presentation of Dermatomyositis?

Answer 7

+/- photosensitivity over face, chest and hands
Gottron’s papules
Gottron’s sign
Rash in V neck distribution

Question 8

What are Gottron’s Papules?

Answer 8

Raised, scaly palpable lesions on extensor surfaces

• MCP joints
• PIP joints
• Elbows

Question 9

What is Gottron’s Sign?

Answer 9

Macules in similar distribution as papules add purplish rash on upper eyelids

Question 10

What are the extramuscular manifestations of Polymyositis and Dermatomyositis?

Answer 10

• Arthralgias
• Arthritis
• Skin disorders
• Fatigue
• Wt loss
• Fever
• Raynaud’s phenomenon

Can affect
- GI
Pulmonary system
Cardiac system

Question 11

What labs are included in Polymyositis and Dermatomyositis?

Answer 11

CBC

• Leukocytosis
• Thrombocytosis

ESR- elevated

CPK- elevated

ANA

Question 12

What diagnostic studies are included in Polymyositis and Dermatomyositis?

Answer 12

MRI to evaluate for amount of muscle involvement

EMG will be abnormal

• ***MUSCLE BIOPSY
• inflammation
• necrosis
• regeneration

Question 13

What medications are used in Polymyositis and Dermatomyositis?

Answer 13

Corticosteroids

• Prednisone 1 mg/kg/day x 4-8 weeks
• Discontinue when CK level in normal range

Immunosuppressants

• Azathioprine
• Cyclophosphamide
• Chlorambucil
• Cyclosporine

Question 14

What are the NON-Medication options for Polymyositis and Dermatomyositis?

Answer 14

Diet- high protein diet

Daily exercise

Rheumatology consult

Question 15

What is the prognosis of Polymyositis and Dermatomyositis?

Answer 15

Majority responds to treatment

Poorer prognosis:

• Age
• AA
• Female
• Interstitial lung disease
• Delayed or inadequate treatment

Question 16

What is included in the DDX of Polymyositis and Dermatomyositis?

Answer 16

***MUSCLE PAIN + WEAKNESS

Drug and toxins
Endocrine diseases
Neurologic disorders
Other Autoimmune Diseases
Metabolic abnormalities
Infectious myopathies