Dermatomyositis

Question 1

Forms of dermatomyositis

Answer 1

• Classic dermatomyositis (autoimmune disease affecting both muscle and skin)
• Amyopathic dermatomyositis (autoimmune disease affecting just skin)

Question 2

Muscle involvement in dermatomyositis

Answer 2

• Symmetric weakness in proximal limb muscles

Question 3

Complications of dermatomyositis

Answer 3

• Malignancy
• Systemic involvement (esp. lungs)
• Diaphragm atrophy
• Calcinosis cutis (calcium deposits in skin)

Question 4

Classic presentation for dermatomyositis

Answer 4

• Skin-wide poikiloderma and pink-violaceous rash often with heliotropic distribution (periocular) and scalp distribution
• Rashes worsen substantially with sunlight, and esp. prominent in neck area due to sun exposure (V-neck sign, shawl sign)
• Muscle weakness in brachium and thigh
• High creatine kinase levels (from muscle degradation)
• Streaks of red in nailfolds
• Flares triggered by stress
• Grotton’s papules in MCPs, PIPs, and/pr DIPs

Question 5

Patients with dermatomyositis often first present to clinic with chronic mild symptoms that are acutely worsening during ____

Answer 5

Patients with dermatomyositis often first present to clinic with chronic mild symptoms that are acutely worsening during a period of social stress

Question 6

Poikiloderma

Answer 6

• Pink-violet rash consisting of areas of hyperpigmentation, hypopigmentation, telangiectasis (widening of blood vessels), and atrophy

Question 7

Onset of dermatomyositis is associated with . . .

Answer 7

. . . an external trigger that interacts with the immune system. Usually a drug or infection.

Question 8

Emerging evidence implicates ___ as the source of pathology in dermatomyositis. This also implicates ___ as the source of ___.

Answer 8

Emerging evidence implicates IFNβ as the source of pathology in dermatomyositis. This also implicates plasmacytoid dendritic cells (pDCs) as the source of IFNβ.

Question 9

Pathognomonic features of dermatomyositis

Answer 9

• Heliotrope eruption
• Grotton’s papules

Question 10

Grotton’s papules are often confused for. . .

Answer 10

. . . psoriasis

Question 11

Cutis cacinosis is often confused for. . .

Answer 11

. . . tophi

Question 12

Answer 12

Grotton’s papules

Question 13

Answer 13

Heliotrope sign

Question 14

Answer 14

Heliotrope sign

Question 15

Lab findings of dermatomyositis

Answer 15

• Elevated creatine kinase
• Elevated lactate dehydrogenase
• Elevated aldolase
• Elevated liver enzymes (ALT AST)
• Imaging studies of muscle to establish atrophy (EMG, MRI, biopsy)

Question 16

Systemic symptoms of dermatomyositis

Answer 16

• Interstitial lung disease (15-30%, antisynthetase syndrome)
• Liver disease
• Muscle degradation
• Increased risk of malignancy
• Fever

Question 17

Antisynthetase syndrome

Answer 17

• Associated with antisynthetase autoantibodies, esp. Jo-1
• Fever
• Erosive polyarthritis
• “Mechanic’s hands” -> hyperkeratosis, fissuring of lateral and palmar aspects of hand
• Reynaud’s phenomenon
• Interstitial lung disease (70% of patients with anti-Jo-1 go on to develop)

Question 18

When dermatomyositis and a malignancy are diagnosed in a close time fashion, the dermatomyositis may be thought of as ____

Answer 18

When dermatomyositis and a malignancy are diagnosed in a close time fashion, the dermatomyositis may be thought of as a paraneoplastic phenomenon

Question 19

Treatment for dermatomyositis

Answer 19

• Corticosteroids
• Methotrexate
• IVIG