DERMATOMYOSITIS

Question 1

what is it?

Answer 1

an inflammatory disorder causing symmetrical, proximal muscle weakness and characteristic skin lesions

Question 2

causes

Answer 2

idiopathic

CTD

malignancy - ovarian, breast, lung

Question 3

what is polymyositis

Answer 3

variant of the disease where skin manifestations

Question 4

what skin features are there?

Answer 4

photosensitive

macular rash over back and shoulder

heliotrope rash in the periorbital region

Gottron’s papules - roughened red papules over extensor surfaces of fingers

‘mechanic’s hands’: extremely dry and scaly hands with linear ‘cracks’ on the palmar and lateral aspects of the fingers

nail fold capillary dilatation

Question 5

other features

Answer 5

proximal muscle weakness +/- tenderness

Raynaud’s

respiratory muscle weakness

interstitial lung disease: e.g. Fibrosing alveolitis or organising
pneumonia

dysphagia, dysphonia

Question 6

Ix

Answer 6

majority of patients ANA positive

around 30% of patients have antibodies to aminoacyl-tRNA synthetases (anti-synthetase antibodies), including:
antibodies against histidine-tRNA ligase (also called Jo-1)
antibodies to signal recognition particle (SRP)
anti-Mi-2 antibodies