Ddx: Idiopathic Inflammatory myopathies (Polymyositis/Dermatomyositis/IBM) Flashcards Preview

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Flashcards in Ddx: Idiopathic Inflammatory myopathies (Polymyositis/Dermatomyositis/IBM) Deck (11):
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Ddx: Idiopathic Inflammatory myopathies (Polymyositis/Dermatomyositis/IBM)

Idiopathic Inflammatory myopathies (Polymyositis/Dermatomyositis/IBM)

Inclusion body myositis

Hypothyroidism

Diabetes mellitus

Drug- and alcohol-induced muscle disease

Infections

SLE, systemic sclerosis, Sjögren syndrome, amyloidosis, vasculitis, rheumatoid arthritis

Critical illness neuromyopathy

Rhabdomyolysis

Still Disease

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Idiopathic Inflamatory myopathies (Polymyositis/Dermatomyositis/IBM)

Hx: Proximal muscle weakness

Physical exam: Heliotrope rash, shawl sign, grotons papules (hyperkeratotic red papules and plaques over bony prominences), rash (heliotrope rash on the upper eyelids and periorbital area, photosensitive rashes involving the shoulders, neck, and anterior chest)

Labs: elevated CK, EMG,Biopsy, Anti Mi/Jo

Dx: Muscle biopsy results from a patient with polymyositis characteristically show CD8-positive T-cell infiltration within the muscle fascicles, often with invasion of intact major histocompatibility complex–expressing muscle fibers.

Dermatomyositis: CD4-positive T cells around the muscle fascicles and in the perimysial areas.

Tx: Steroids

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Inclusion body myositis

Also an inflammatory muscle disease that causes asymmetric proximal and distal weakness; more common than polymyositis in older people; does not respond well to glucocorticoids and immunosuppressants. Biopsy showing evidence of filamentous inclusions is diagnostic.

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Hypothyroidism

Can cause weakness, stiffness, and elevated CK level. Screen with serum TSH measurement.

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Diabetes mellitus

Can cause fatigue and generalized muscle weakness. Diabetes may also cause neuropathies and plexopathies.

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Drug- and alcohol-induced muscle disease

Can cause weakness and possibly pain and elevated CK levels. Consider glucocorticoids, statins, fibric acid derivatives, and organophosphate poisoning.

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Infections

Viruses often cause pain and may cause frank myositis. Consider bacterial infection, trichinosis, and other parasitic infections.

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SLE, systemic sclerosis, Sjögren syndrome, amyloidosis, vasculitis, rheumatoid arthritis

May mimic myositis, have an element of myositis, or coexist independently of polymyositis.

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Critical illness neuromyopathy

Profound generalized weakness following prolonged therapeutic paralysis in an intensive care unit; caused by a combination of muscle and nerve dysfunction.

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Rhabdomyolysis

Acute muscle necrosis with myoglobinuria leading to acute kidney injury; caused by drugs, alcohol, trauma, seizures, and muscle disease. CK level usually is >10,000 U/L.

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Still Disease

Hx: Systemic inflammatory disorder characterized by quotidian (daily) fever, evanescent rash, arthritis, and multisystem involvement.

Dx: Based on the typical clinical presentation and exclusion of infection and malignancy, particularly leukemia and lymphoma.

Leukocytosis, anemia, thrombocytosis, elevated erythrocyte sedimentation rate, elevated serum ferritin level (≥1000 ng/mL [1000 µg/L]), and abnormal liver chemistry tests; antinuclear antibody titer and rheumatoid factor typically are negative.