Dermatomyositis

Specific underlying cause is unknown

Possible environmental factors including viruses (seasonal pattern of incidence)

Bimodal age distribution

10-15 years-old; 40-60 years-old

Occurs in 1 per 100,000 cases

Possible links to HLA alleles

Genetic component may be less than in other autoimmune disorders

Inflammatory myopathy

Antigen specific antibodies

Attack against muscle capillaries and endothelium

Perivascular and perimysial infiltration

Elevated CK, aldolase, AST, ALT, LDH

Elevated ESR and CRP

Myositis-specific autoantibodies

Anti-jo-1

Anti-Mi-2

Anti-SRP

Gottron papules

Gottron sign

Heliotrope eruption

Facial erythema

Poikilodermatous eruption

Holster sign

Nailfold abnormalities

Psoriasiform changes in scalp

Mechanic's hands

Calcinosis cutis

Periungual telangiectasia

Reduced proximal muscle strength

Muscle atrophy

Myalgias and muscle tenderness

Joint pain and swelling

Muscle weakness

Insidious onset

Symmetrical proximal muscle weakness

Difficulty rising from a low chair

Difficulty walking upstairs

Difficulty washing hair

Difficulty getting out of a car

Difficulty reaching overhead

Difficulty combing hair

Systemic glucocorticoids (prednisone)

Glucocorticoid sparing immunosuppressive agents

Mycophenolate mofetil

Rituximab

Vitamin D and calcium supplementation

If taking 5mg/day or more of steroids for more than 3 months

Physical therapy

Daily exercise to maintain and restore normal function

Smoking cessation

Healthy diet

Fruits, vegetables, whole grains, lean protein

Muscle biopsy

Confirms diagnosis

MRI

Detects muscle inflammation and damage

Electromyography