Rheumatology: Polymyositis and Dermatomyositis

Question 1

Whats the difference between polymyositis (PM) and Dermatomyositis (DM)?

Answer 1

PM-inflammation invades all the way through

DM- inflammation doesn’t invade the fascicle

Question 2

what skin diseases occur in PM/DM?

Answer 2

• gottron’s papules- red rash on hand joints
• Heliotrope rash- blue purple rash on upper eyelids
• V-sign and shawl-sign rash- red V shape rash on chest and shoulders
• Mechanics hands
• periungal erythema- crusties around cuticle

Question 3

Myositis specific antibodies (MSAs) are:

Answer 3

• Anti-synthetase antibodies (oftentimes Anti-Jo-1 is present, an anti histadyl tRNA synthetase)
• Anti-Mi-2 antibody
• Anti-signal-recognition particle (SRP) antibodies

Question 4

Myositis-associated antibodies (MAAs) are:

Answer 4

antinuclear antibodies (+ANA)

Question 5

What is important to remember when doing an EMG?

Answer 5

always obtain an EMG on one side and the muscle biopsy on the other side so the biopsy interpretations don’t get complicated.

Question 6

What sort of muscle weakness accompanies PM/DM?

Answer 6

symmetric proximal

Question 7

ESR is used to detect _______

Answer 7

inflammation

Question 8

How can someone have a urinalysis with + blood but no cells?

Answer 8

Myoglobinuria

Question 9

What are expected EMG and muscle biopsy results?

Answer 9

decreased amplitude, increased insertional activity

Question 10

What is anti-synthetase syndrome?

Answer 10

inflammatory arthritis, Interstitial Lung disease, Raynauds, mechanics hands, fever, anti-alphaJo-1

Question 11

What abnormalities in cellular immunity, humoral immunity, and nonimmune mechanisms support DM?

Answer 11

cellular- Increased #s of activated T lymphocytes, IL-1, TNF, INFgamma.
humoral- See B cells in tissues and Abs and immune complexes in the tissue.
nonimmune- damage to vessels and tissues

Question 12

muscle biopsy in PM reveals what?

Answer 12

CD8+ cells throughout fascicle

Question 13

muscle biopsy in DM reveals what?

Answer 13

CD4+ cells in perifascicular and perivascular layers

Question 14

What evidence supports that viruses may be an initiating factor in DM/PM?

Answer 14

alot of INF in the muscle. This controls viruses as well as CD8+ T cells so going to be more susceptible to viruses. Viruses can cause muscle problems.

Question 15

Treatment of PM/DM is what?

Answer 15

direct at suppressing autoimmune inflammatory response.

Question 16

In PM/DM we find elevated levels of _______ and EMGs reveal _______

Answer 16

serum muscle enzymes (CPK)

myopathic findings

Question 17

myositis-specific antibodies are found in ________

Answer 17

anti-synthetase syndrome