Chapter 43 - Dermatomyositis

Question 1

What infectious agents have been implicated in the pathogenesis of DM?

Answer 1

Picornavirus, E. coli, echovirus, coxsackievirus, AIDS

Question 2

What medications have been implicated in the pathogenesis of DM?

Answer 2

D-penicillamine, hydroxyurea, NSAIDs, statins, phenytoin, lenercept, alfuzosin

Question 3

What is the most diagnostic feature of skin eruption of DM?

Answer 3

Poikiloderma. Next is photodistribution and nail fold changes

Question 4

For patients with no underlying malignancy, what is a major prognostic factor for death in patients with DM?

Answer 4

Cardiac involvement (rhythm disturbances, conduction defects)

Question 5

What type of internal malignancies are associated with adult DM?

Answer 5

GU (ovarian, colon), breast, lung, gastric, pancreatic, lymphomas (including non-Hodgkin) and other female genital cancers. The frequency is anywhere from 10% to over 50%

Question 6

After DM is confirmed on skin biopsy, what other tests should be done to evaluate muscle involvement?

Answer 6

) Strength testing, 2) serum muscle enzymes, 3) EMG, 4) tricep muscle biopsy, 5) U/S or MRI of proximal muscles, 6) +/- investigations for systemic symptoms (eg. CXR, PFT’s, ECG) and to rule out malignancy

Question 7

What is the 1st line treatment for the myopathy in DM?

Answer 7

Prednisone 1 mg/kg, taper 50% over 6mths, taper to 0 over 2–3yrs. There is discordance between skin and muscle disease

Question 8

Dermatomyositis is associated with an increased risk of lymphoma, as well as a variety of carcinomas. Which two carcinomas are most commonly associated?

Answer 8

Ovarian cancer and colon cancer

Question 9

True or false: the risk of malignancy associated with dermatomyositis may return to normal 2-3 years after the diagnosis.

Answer 9

True

Question 10

The reported frequency of internal malignancy associated with adult dermatomyositis varies between 10% and 50%. What is the reported frequency of malignancy seen in patients with polymyositis?

Answer 10

There is no association with internal malignancy

Question 11

List the three connective tissue disorders that most commonly overlap with dermatomyositis.

Answer 11

Systemic lupus erythematosus, rheumatoid arthritis, and scleroderma
*Every patient with dermatomyositis should be asked about, or investigated for, arthritis, renal disease, GI disease, neuropathy, and Raynaud’s

Question 12

Can patients with dermatomyositis have cardiac involvement?

Answer 12

Yes, and it’s usually asymptomatic. When symptoms do occur, it’s usually related to a rhythm disturbance

Question 13

Does the pulmonary involvement of dermatomyositis respond to steroids?

Answer 13

No; it’s resistant to steroids and follows an independent course from the muscle disease of dermatomyositis