Rheumatology

Question 1

Dermatomyositis

1. what are the skin features
2. other features?
3. investigations

-autoimmune
-common in women 50-70
-can also be paraneoplastic disease (ovarian, breast and lung tumors)
-causes symmetrical proximal muscle weakness + skin lesions
-may be ideopathic or associated with CTD or underlying malignancy
-polymyositis is variant where skin manisfestations are not prominent

Answer 1

1. 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
2. Other features
   -proximal muscle weakness +/- tenderness
   -Raynaud’s
   -respiratory muscle weakness
   -interstitial lung disease: e.g. Fibrosing alveolitis or organising pneumonia
   dysphagia, dysphonia
3. Investigations
   the majority of patients (around 80%) are 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