Dermatomyositis

Question 1

Dermatomyositis is an autoimmune mediated connective tissue disease that causes inflammatory disease that causes muscle weakness and characteristic skin lesions. What is the incidence of dermatomyositis?

1 - 1 : 100
2 - 1 : 1000
3 - 1 : 10,000
4 - 1 : 100,000

Answer 1

4 - 1 : 100,000

Question 2

Dermatomyositis is an autoimmune mediated connective tissue disease that causes inflammatory disease that causes muscle weakness. Does it affect men or women more?

Answer 2

• women

Question 3

Dermatomyositis is an autoimmune mediated connective tissue disease that causes inflammatory disease that causes muscle weakness. What age is the peak incidence?

1 - 20-30 years
2 - 30-40 years
3 - 40-50 years
4 - 50-60 years

Answer 3

4 - 50-60 years

Question 4

Although the exact cause of dermatomyositis is unknown, it is though that it is caused by an abnormal immune response. normally do host cells present MHC-1 or MHC-II to cytotoxic T cells?

Answer 4

• MHC-1
• check is the antigen presented on the MHC-1 is a self antigen
• however, if the cell is infected or damaged the cytotoxic T cell will induce cell apoptosis

Question 5

In dermatomyositis, it has been suggested that cytotoxic T cells bind to MHC-1 on skeletal muscle, but react as though the antigen is foreign. What is the term used when host antigens resemble foreign antigens?

1 - mirroring
2 - molecular mimicry
3 - cross reactivity
4 - molecular camouflage

Answer 5

2 - molecular mimicry

When T cells react to host antigens, this is called autoantigens

Question 6

If a CD8 (cytotoxic) T cell binds to a host antigen on skeletal muscle cells but recognises it as foreign then the T cell will induce apoptosis. Which other cell can also begin producing antibodies against the skeletal muscle?

1 - CD4 T helper cells
2 - neutrophils
3 - macrophages
4 - B cells

Answer 6

4 - B cells

Question 7

B cells can produce antibodies that target skeletal muscle in dermatomyositis. Which antibodies are produced that are specific to muscle aspect of dermatomyositis?

1 - anti-Ro
2 - anti-La
3 - anti-tRNA synthetases (Jo-1)
4 - anti-Mi-2 nuclear protein (Mi-2)

Answer 7

3 - anti-tRNA synthetases (Jo-1)
4 - anti-Mi-2 nuclear protein (Mi-2)

• ANA are present, but non specific
• this is typically how patients are diagnosed
• muscle biopsy can also be used

Question 8

Once skeletal muscles begin being damaged by cytotoxic T cells, there is inflammation in the surrounding tissues. The damage muscle also leak which enzymes into the blood that can be measured and help with diagnosis?

1 - creatine kinase,
2 - aldolase
3 - lactate dehydrogenase
4 - all of the above

Answer 8

4 - all of the above

Question 9

Although the exact cause of dermatomyositis is unknown, there are some genetic risk factors. Which of the following HLA are associated with an increased risk of dermatomyositis?

1 - HLA-B27
2 - HLA-DR3
3 - HLA-DR5
4 - HLA-A

Answer 9

2 - HLA-DR3
3 - HLA-DR5

Question 10

Although the exact cause of dermatomyositis is unknown, there are some genetic risk factors. Which 2 of the following are associated with an increased risk of dermatomyositis?

1 - coxsackie virus
2 - type 2 diabetes
3 - malignant antigens
4 - COPD

Answer 10

1 - coxsackie virus

3 - malignant antigens
- specifically ovarian, lung and breast

Question 11

All of the following are common presenting clinical features associated with skeletal muscle in dermatomyositis. Which of the following is the most common feature?

1 - muscle weakness
2 - muscle tenderness
3 - raynaud’s
4 - respiratory muscle weakness
5 - interstitial lung disease
6 - dysphagia
7 - dysphonia (vocal changes)

Answer 11

1 - muscle weakness

• this is often bilateral

Question 12

Progressive muscle weakness and pain are common clinical features of dermatomyositis. Which 2 of the following are most commonly affected?

1 - shoulder muscles
2 - pelvic girdle muscles
3 - arm muscles
4 - leg muscles

Answer 12

1 - shoulder muscles
2 - pelvic girdle muscles

• flexors of the neck may also be affected

Question 13

Which of the following can be used to diagnose dermatomyositis in the muscles?

1 - grip strength
2 - sit to stand
3 - electromyography
4 - MRI

Answer 13

3 - electromyography

• able to identify dead or weak muscles

Question 14

In dermatomyositis the skin and muscle is affected. One of the skin features is a purplish rash in the periorbital region. What is this called?

1 - heliotrope rash
2 - erythema
3 - bullous pemphigoid
4 - malar rash

Answer 14

1 - heliotrope rash

• malar rash can occur, but this is on the cheeks, and is less common

Question 15

In dermatomyositis the skin and muscle is affected. One of the skin features is a red, often scaly, bumps overlying the knuckles of the fingers. What is this called?

1 - heliotrope rash
2 - gottron’s papules
3 - bullous pemphigoid
4 - malar rash

Answer 15

2 - gottron’s papules

May also see the following on the hands:
- purple erythematous flat or raised lesions on the knuckles
- mechanic’s Hands: there is cracking and fissuring of the skin of the finger pads

Question 16

Of all the rashes associated with dermatomyositis, which of the following is NOT correct?

1 - itchy
2 - painless
3 - bleed
4 - photosensitive

Answer 16

2 - painless
- typically painful

Question 17

Once diagnosed, what is the 1st line treatment for dermatomyositis?

1 - Corticosteroids
2 - Immunosuppressives
3 - Intravenous Immunoglobulins (IVIG)
4 - Muscle stimulation

Answer 17

1 - Corticosteroids
- prednisolone is 1st choice
- aim is to suppress the immune response

Question 18

Once diagnosed, the 1st line treatment for dermatomyositis is corticosteroids. If this fails immunosuppressives can be tried. Which of the following is NOT an immunosuppressive?

1 - Methotrexate
2 - Anastrozole
3 - Azathioprine
4 - Cyclophoshamide

Answer 18

2 - Anastrozole
- hormone medication