polymyositis and dermatomyositis

Question 1

what is polymyositis?

Answer 1

an autoimmune idiopathic, chronic condition causing inflammation of the muscles

Question 2

what is dermatomyositis?

Answer 2

-an idiopathic, autoimmune, connective tissue disorder where there is chronic inflammation of the skin and muscles

Question 3

what can cause dermatomyositis/polymyositis?

Answer 3

underlying malignancy

most commonly:

• lung
• breast
• ovarian
• gastric

Question 4

what is a paraneoplastic syndrome?

Answer 4

-a group of disorders that are triggered by an abnormal immune response to a cancerous tumour

Question 5

what is an example of paraneoplastic syndrome?

Answer 5

polymyositis and dermatomyositis

Question 6

how does polymyosytosis present?

Answer 6

-gradual onset of muscle weakness, usually affecting proximal muscles (hip and shoulder) and is typically symmetrical

Question 7

how does dermatomyositosis present?

Answer 7

• Gottron’s sign (red/purple colour behind PIP joint)
• Heliotrope rash (red/purple rash around eyes)
• Shawl sign (red/purple rash on back of shoulder area/chest)
• muscle weakness

Question 8

what investigations are done for polymyositis and dermatomyositis?

Answer 8

• Bloods (raised CREATINE KINASE, CRP, PTH/TSH)
• muscle biopsy
• EMG

antibody test:

• anti-jo-1 antibodies (polymyositis)
• anti-mi-2 antibodies (dermatomyositis)
• ANA antibodies

Question 9

what is the treatment for polymyositis and dermatomyositis?

Answer 9

prednisolone (40mg)

combined with methotrexate or azathioprine