Seminar G Dermatomyositis and Polymyositis Flashcards Preview

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Flashcards in Seminar G Dermatomyositis and Polymyositis Deck (17):
1

Definition

Polymyositis is an autoimmune disease characterised by inflammation of striated muscle.

2

Epi

2-10 per million/yr

3

Female:Male

2.5:1

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Peak mean ages

Childhood and 40-50 years

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Aetiology and Pathogenesis

Associations with HLA-DR3 and Drw52
First degree relatives

6

Environmental factors

More common in winter and spring
Influenxa
Coxsackie
Echo

7

Drug induced myositis

HMG-CoA reductase inhibitors (Statins)
D-penicillamine
Chloroquine

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Hallmark Feature

Painless proximal muscle weakness

9

More advanced disease

Pharyngeal musculature result difficulty in initiating swallowing, whilst exertional dyspnoea may result from respiratory muscle weakness.

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MRC motor scale

May be used to record muscle power

11

Blood tests

Acute phase response, with a raised ESR or plasma viscosity
Anaemia
Muscle enzymes will be grossly elevated, as they leak from damaged skeletal muscle.

12

Creatine Kinase (CK)

Most sensitive and best guide to muscle inflammation, but other enzymes such as lactate dehydrogenase, and the transaminases (ALT and AST) may

13

Autoimmune profile may show

Positive Antinuclear (ANA) and anti-Jo-1 antibodies may also be present.
An electromyogram

14

Treatment → Symptoms

Oral prednisolone

15

Treatment → Other Agents

Azathioprine
Methotrexate

16

Treatment → Prevent glucocorticoid-induced osteoporosis

Bisphosphonates

17

Association with Malignancy →
Underlying neoplastic lesions seen in 10-15% of cases in the first 6 months.
Examples:

1. Adenocarcinoma of the colon
2. Prostatic carcinoma
3. Ovarian tumours
4. Breast cancers

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