JDM

Question 1

Which HLA allele was found to be a major immunogenetic risk factor?

Answer 1

HLA DRB1*0301 allele

Question 2

Pathogenesis of JDM

Answer 2

PDCS circulate in the blood and upon activation by viral infection, upregulate CCR7 —> migrate to lymphoid tissues

• Cells recognize viruses through TLR9–> induce maturation of DCs—> activation of T cells
• pDCs also produce Type I IFN
• Can also see overexpression of MHC class I molecules
• Increased expression of CXCL9, CXCL10 and CXCL11
• Type I IFN also enhances auto antibody formation and B cell proliferation
• ENdothelial cells produce IL-1, VCAM-1 and other adhesion molecules

Question 3

Bohan and Peter criteria

Answer 3

Presence of pathognomonic rash (heliotrope and Gottron papule) and 3 of the following 4 features

• Proximal muscle weakness
• elevated inflammatory markers
• EMG changes of chronic inflammatory myositis
• Histo patty changes of inflammatory myositis

Question 4

Anti-p155/140

TIF-1 gamma

Answer 4

• Severe cutaneous disease
• Greater muscle weakness
• Lipodystrophy, skin ulceration, edema
• In adults, strong association with malignancy

Question 5

Anti-MJ

NXP2

Answer 5

• Younger onset at disease onset
• Calcinosis
• Greater degree of muscle weakness
  Predicts poor prognosis; frequent muscle cramps, atrophy, joint contractors, and dysphonia, GI ulcerations and bleeding

Question 6

Anti-MDA5

Answer 6

Rapidly progressive ILD
Higher IL 18, 1L-6 and ferritin;
Fever and milder muscle disease (low CK levels)
Amyopathic

Question 7

Anti-SAE

Answer 7

Initially Amyopathic disease in adult DM

Question 8

Anti-Jo1 (Anti-ARS)

Answer 8

Antisynthetase syndrome;
Fever, ILD, RP, mechanics hands, non erosive arthritis,
- Better prognosis compared to anti Jo negative

Question 9

Anti-SRP

Answer 9

Severe symmetrical muscle weakness, RP, very high CK levels, cardiac disease, dysphagia, ILD

• Older age, insidious onset
• Found more in JPM

Question 10

Anti Mi

Answer 10

Cutaneous features, better prognosis

- Milder muscle, decreased risk of ILD, malignancy, responds well to standard therapies

Question 11

EMG findings associated with JDM

Answer 11

• Increased spontaneous and insertional activity

- Low amp, short duration, polyphasic motor unit action potentials and early recruitment

Question 12

Muscle biopsy

Answer 12

Perifascicular atrophy 
Muscle fiber size variation 
Muscle degeneration and regeneration
centralization of the nuclei 
Vasculopathy
swelling of the capillary endothelium 
and perivascular infiltration of pdcs, B and T cells and macrophages 

Staining of MXA may correlate with disease activity

Question 13

Amyopathic Dermatomyositis

Answer 13

Patients with characteristic rash without evidence of muscle involvement

• Milder disease
• Less frequent myalgia, arthritis, contractors, calcinosis, dysphagia, abdominal pain and fatigue

Question 14

Juvenile Polymyositis

Answer 14

• Older age
• More severe muscle weakness
• higher CK level
• Frequent falls, RP, dyspnea, cardiac abnormalities
• Histo path shows mixed area of necrosis and regenerative muscle fibers, CD8T cells and macrophages
• Scattered as opposed to focal (JDM) as well as absence of vasculopathy

Question 15

Most common malignancies associated with IIM

Answer 15

leukemia
lymphoma
CNS tumors

Question 16

Histo path of skin with JDM

Answer 16

Vacuolar interface dermatitis with dermal mucin deposition

Question 17

When should IVIG be used in JDM

Answer 17

If patients haven’t responded well to steroid and MTX, esp if skin disease is very active.

Question 18

Predictors of longer time to remission

Answer 18

Abnormal nail fold capillaries

Continued presence of rash 3 months after diagnosis

Question 19

Muscle strength test

Answer 19

1. Trace or flicker of muscle movement
2. Able to move if gravity is removed
3. Only able to move against gravity, no resistance
4. Able to move some against resistance
5. full strength

Question 20

What is the most common autoimmune disease associated with lipodystrophy?

Answer 20

• JDM