What are the clinical manifestations of myositis?
- Slowly progressive, fixed proximal muscle weakness
- ↑ CPK
- post-exertional pain
What are Dx criteria for polymoysitis?
- Symmetrical weakness of limb-girdle muscles and anterior neck flexors.
- Biopsy ==> inflammation in center of muscle fascicle, CD8, no B cells, No vasculopathy
- ↑ CPK and serum enzymes (they are variable)
- Electromyographic triad: short, small, polyphasia motor units, fibrillations and sharp waves; and bizarre, repetitive discharges. (Variable)
What are clinical manifestations of dermatomyosistis?
- polymyositis + rash
- Lilac HELIOTROPE around eyelids
- Periorbital edema
- Scaly erythema on MCP and PIP (GOTTRON’S SIGN)
- Rash ==> neck and V-SIGN on torso (rash can be elsewhere, too)
- Capillary nail fold changes and PERIIUNUAL ERYTHEMA
What are the differences in biopsy features between Polymyositis and Dermatomyositis?
Polymyositis • inflammation in center of muscle fascicle • CD8, no B cells • No vasculopathy Dermatomyositis • inflammation perifascicular muscle • CD4, B cells • Vasculopathy and complement deposition
(detail) What are autoantibodies in polymyositis and dermatomyositis?
- ANA 90% ==> non-specific
- Ro, La, RNP 20% ==> secondary to other autoimmune
- Jo-1 20% ==> PM/DM and myositis specific + LG dz, and raynauds (anti-synthetase syndrome)
- SRP 5% ==> specific to PM ==> prognosis bad
- Mi-2 10% ==> specific to DM
What pulmonary dz are associated with myositis?
- interstitial pneumonitis, alveolitis, fiborisis
* LGs are most common secondary organ
What are the features of juvenile dermatomyositis?
- Adult +
- Vasculitis
- Lipodystrophy
- Calcinosis
What is Tx of PM/DM?
- steroids
- MTX azathioprine
- Skin is difficult to Tx
What are the features of Inclusion Body Myositis?
- Rare
- Elderly males
- Weakness pattern»_space; Proximal, symmetric or Distal, Assymmetric
- Intractable to Tx
- Gradual
What are the histological features of Inclusion Body Myositis?
• infiltrate, rimmed vacuoles, inclusions, amyloid, mt abnormalities
What are examples of myopathies?
Rhabdomyolysis
Drug-induced myopathy (steroids)
Metabolic myopathies
DDx with Polymyalgia Rheumatica and myositis
What are differences between statin and steroid myopathies?
Statin Myopathies • MYALGIA, WEAKNESS • anytime, usually when Tx is started • CPK = 1000 • Rare aggressive, requires immunosuppression
Steroid Myopathies (sep predinisone) • WEAKNESS • Type 2 muscle atrophy • Prolonged treatments • Dx: stop steroids, symptoms improve
General Clinical Presentations of Metabolic Myopathies?
• dynamic weakness • exercise intolerance • myoglobemia • CV and neuro involvements There are primary and secondary metabolic myopathies. See my notes for details
What are the manifestations of Polymyalgia Rheumatica?
- > 50 y/o
- Rapid onset hip/shoulder pain
- Inability to walk due to pain
- Inflammation, but not of muscles ↑ ESR or ↑ CRP
- Tenderness to palpation
- CPK normal, no autoantibodies, strength fine
- Tx steroids with rapid improvement
