Idiopathic Inflammatory Myopathies Flashcards
1
Q
Define IIM
A
Idiopathic inflammatory myopathies constitute a heterogeneous group of sub-acute, chronic, and, rarely, acute diseases of skeletal muscle (polymyositis & dermatomyositis)
2
Q
Explain the aetiology / risk factors of idiopathic inflammatory myopathies
A
- Children (dermatomyositis)
- Age 40-60
- Female and/or black ethnicity
- UV radiation (dermatomyositis)
- HIV
3
Q
Recognise the presenting symptoms of idiopathic inflammatory myopathies (incl. polymyositis, dermatomyositis)
A
Both:
- PROGRESSIVE muscle weakness & DIFFICULTY WITH MOTOR TASKS: Trouble climbing stairs/getting up from chair/lifting objects (bilateral proximal myopathy)
- Myalgia
-
Systemic Sx:
- Fever
- Malaise
- Weight Loss
DERMATOMYOSITIS:
- Blue-lilac (Heliotrope) rash on sun-exposed areas & eyelid oedema
- Gottron’s papules: red-rash over knuckles & knees
4
Q
Recognise the signs of idiopathic inflammatory myopathies (incl. polymyositis, dermatomyositis) on physical examination
A
- Proximal myopathy: Ask pt to stand from sitting position with their arms crossed
- Muscle atrophy
- Heliotrope rash (may go over eyelids)
- Shawl’s sign: rash over neck
- Gottron’s nodules
5
Q
Identify appropriate investigations for idiopathic inflammatory myopathies (incl. polymyositis, dermatomyositis) and interpret the results
A
- Muscle biopsy (DIAGNOSTIC): PM –> endomysial infiltrate and DM –> perimysial infiltrate
- CT CAP in dermatomyositis as it is associated with malignancy
- Serum CK: Elevated
- Serum LDH: Elevated
- Serum aldolase: Elevated
- Myoglobin: Elevated
- Serum ALT: Elevated
- ESR: Elevated
- ANA, Anti-Mi2, Anti-Jo1: ANA elevated, Mi2 in DM, Jo1 in PM
6
Q
Management
A
- High dose prednisolone (40-60mg) for active inflammation
- this should be tapered according to clinical response
- DMARDs to reduce inflammation and maintain remission (MTX, AZT, MMF)
- IVIG for severe/refractory inflammation
