inflammatory myopathy Flashcards
what are the three inflammatory myopathies ?
dermatomyositis
polymyositis
inclusion body myositis
what is the clinical picture of inflammatory myopathies ?
- insidious onset
- fever and weight loss
- non-erosive inflammatory polyarthritis
- Raynaud’s phenomenon
which muscles are mostly affected inn polymyositis and dermatomyositis ?
- proximal muscles of the limb (symmetrical)
upper and lower limb
along with affection of the pharyngeal and respiratory muscles
- pharyngeal and respiratory muscle weakness
what type of movements would these patients have difficulties performing ?
difficulty getting up from the chair
difficulty combing hair
difficulty climbing stairs
what are the skin manifestations in dermatomyositis ?
- heliotrope rash on eyelids
- rash on the face neck and chest ( V sign )
- Rash on back and shoulders ( shawl sign)
- Gottrons papules
- gottrons rash
- mechanics hand
- dilated nail bed capillary loops
- subcut calcifications
- holster sign
what are the features of heliotrope rash ?
purple discoloration on the eyelids specific to deermatomyositis
what are gottorns papules ?
papules on the MCP that are diagnostic of dermatomyositis
what does mechanic hand look like ?
rough and cracked skin on the lateral aspect of index fingers and thumb
what type of patients are more likely to have calcinosis ?
juvenile dermatomyositis
what is the onset of polymyositis ?
subacute onset
what is the clinical presentation of polymyositis?
weakness affecting proximal muscles no rash dysphagia AV conduction defects- arrhythmia ILD
what lab investigations would we order for a diagnosis of DM or PM ?
turn you muscles into CLAA (clay)
CK
LDH
Aldolase
AST
ALT
when can we find CK levels to be normal ?
active dermatomyositis and inclusion body myositis
what would we find on EMG ?
increased spontaneous activity and fibrillations
what are the differences in PM and DM in muscle biopsy ?
DM: layers of atrophic muscle fibres at the periphery of fascicles is diagnostic
PM: CD8 lymphocytic infiltration ( directed against MHC-1)
what is the treatment for inflammatory myopathy ?
1- predinsolone ( very responsive to steroids)
muscle strength usually lags behind improvement in muscle enzymes
2- hydroxychloroquine for dermatomyositis
what is the dose for predinsolone given ?
0.5-1.5 mg per kg per day then reduce by 5mg per week then reduce by 2.5 mg every 2 weeks
what can we give alongside the predinsolone ?
biphosphonate
what are the immunosuppressive drugs taken in `pm and Dm
cyclophosphamide azathioprine mycophenolate mofitil cyclosporine methotrexate
what are the feature of inclusion body myositis ?
affection of males more
only above 50
affection is bilateral but not symmetrical
affection of both distal and proximal muscle affection
non responsive to steroids
what does the holster sign show ?
poikiloderma in sun protected areas
what is poikiloderma ?
triad of :
tenelgectasia
mottled hypo-hyperpigmentation
atrophy
what is the association of dermatomyositis and malignancies ?
lung
breast
colon
ovary
what type of respiratory failure would be associated with PM and DM ?
type 2
low oxygen
high co2
if the oesophageal muscles or pharyngeal muscles are affected what would the presentation be ?
dysphonia
dysphagia
what are the differential diagnosis of proximal symmetrical muscle weakness ?
other than PM and DM
acquired myopathies ( steroid induced , statin induced and with thyroid disease )
to obtain a definitive diagnosis of PM orr DM ?
muscle biopsy
how would you differentiate between polymyositis and polymyalgia ?
both present with proximal muscle weakness
polymyositis is associated with pain
polymyalgia is associated with stiffness
