Dermatomyositis

Question 1

what is it?

Answer 1

clinically similar to polymyositis other than the addition of typical cutaneous features

Question 2

what are the typical cutaneous features?

Answer 2

Gottron’s papules Heliotrope rash V-shaped rash over the chest

Question 3

what are the investigations?

Answer 3

as for polymyositisraised inflammatory markers CK raised often 10x normal Immunology - ANA, anti-RNP: shared with other AI diseases - Anti-Jo-I, anti-SRP: unique to myositis MRI - localize extent of muscle involvement - show signal intensity abnormalities of muscle due to inflammation, oedema, scarring EMG- abnormal muscle biopsy - crucial - excluding other rare muscle diseases - muscle fibres in varying stages of inflammation, necrosis, regeneration

Question 4

what does dermatomyositis have an associated risk of?

Answer 4

malignancy - 25% of patients - greatest in the 5 years following diagnosis - common cancers: breast, ovarian, lung, colon, oesophagus, bladder - should screen for malignancy at diagnosis