polymyostitis / dermatomyostitis

Question 1

What is polymyositis/dermatomyositis? (2)

Answer 1

Inflammation + necrosis of skeletal muscle
Where skin is involved it is called dermatomyositis

can affect lungs - paraneoplastic syndrome

Question 2

Treatment for polymyositis/dermatomyositis? (2)

Answer 2

Bed rest + prednisolone (1 month then taper dose down)

=> Steroids and then immunosuppressive drugs (azathioprine)

Question 3

Symptoms of polymyositis/dermatomyositis? (6)

Answer 3

Symmetrical wasting of muscles of shoulders + pelvic girdle
- Hard to stand from sitting, to squat
- Hard to put hands on top of head

Dermatomyositis = + skin changes
- Gottron papules- scales on knuckles
- Heliotrope - purple eyelid

Question 4

Risk factors for polymyositis/dermatomyositis? (2)

Answer 4

-Females
-HLA B8/DR3 genetic link

Question 5

Investigations to diagnose polymyositis/dermatomyositis? (4)

Answer 5

• Muscle enzymes (Creatine Kinase over 1000 U/l) - will be high because released during necrosis
• Muscle fibre biopsy, necrosis = diagnostic
• LDH raised
• Anti Jo1 + Anti Mi2 Ab’s –> (Mi2 is dermatomyositis only)

Question 6

autoantibodies

Answer 6

• Anti Jo1 + Anti Mi2 Ab’s –> (Mi2 is dermatomyositis only)

Question 7

which muscles are involved

Answer 7

symmetrical muscle wasting of shoulders and pelvic girdle