SM 246: Inflammatory Myopathies Flashcards

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1
Q

What is the most common cause of acquired myopathies?

A

Inflammatory/autoimmune myopathy - these are treatable

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2
Q

What is an inflammatory myopathy?

A

An inflammatory response against normal muscle, supporting stroma, or muscle as one of many target tissues

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3
Q

Is all inflammation in muscle an “autoimmune myopathy”?

A

No - just because you see inflammation on biopsy, doesn’t mean you have inflammation

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4
Q

Do you need inflammation for an “autoimmune myopathy”?

A

Also no, might not catch it on muscle biopsy

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5
Q

What are the 4 broad types of inflammatory myopathy?

A

Polymyositis, Deramtomyositis, Inclusion Body Myositis, and Necrotizing Autoimmune Myopathy

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6
Q

What are the two types of Dermatomyositis?

A

Adult with or without skin involvment, as well as Juvenile

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7
Q

How do all myopathies present in general?

A

Proximal muscle weakness, no sensory complaints, myalgias and other sites of inflammation throughout the body

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8
Q

How do myopathies effect patients?

A

Effect day to day activities like sitting, standing, and applying makeup

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9
Q

What is a myalgia?

A

A muscle pain like running a marathon, sore

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10
Q

Is shortness of breath associated with myopathy?

A

Yes

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11
Q

What should you ask about in ROS for a myopathy?

A

Urine color changes (Rhabdo/tea colored urine), swallowing issues (choking issue), medications (statins)

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12
Q

What is the urine color change you should be worried about in a myopathy?

A

Tea colored urine = rhabdomyolysis

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13
Q

Which medications can cause myopathy?

A

Statins

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14
Q

What medical conditions can cause myositis and myopathy?

A

Connective tissue diseases, sarcoidosis, and renal/liver

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15
Q

What should you look for on physical exam in a myopathy?

A

Muscle bulk/atrophy/fasciculations, check proximal and distal muscles (especially head and neck extensors), Deep Tendon Reflexes (DTRs) and sensory exam

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16
Q

What are fasciculations, and what could they suggest?

A

Twitches, ALS

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17
Q

Why should you assess head and neck extensors in a muscle weakness patient?

A

They may go into respiratory failure if they can’t extend their head and neck

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18
Q

What are DTRs?

A

Deep Tendon Reflexes

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19
Q

What labs should you order in a suspected myopathy?

A

CK, aldolase + lactic acid, urine Myoglobin, ESR and CRP Myositis antibodies EMG/MRI Muscle biopsy

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20
Q

What are ESR and CRP related to?

A

Acute phase inflammation, possibly found in myopathy

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21
Q

How is an MRI useful in a myositis?

A

White areas on an MRI correspond to inflamed muscle and guide biopsy

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22
Q

How does polymyositis present?

A

Symmetric proximal muscle weakness, occasional facial weakness + dysphagia, myalgias/achiness, slow onset (except for SRP)

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23
Q

What type of polymyositis is rapid onset?

A

SRP Polymyositis is fast/few weeks, due to antibodies, other things are slow

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24
Q

How does myositis affect the lung?

A

Myositis often cooccurs with fibrotic lung disease, and should be testing for potential lung disease with Anti-Jo1 antibody

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25
Q

What is the Anti-Jo1 antibody used for?

A

Tests for potential lung involvement/ILD and urgent pulmonology referral in a myositis patient

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26
Q

What nonspecific symptoms does polymyositis produce?

A

Myalgias, seronegative arthritis, and occasional fever

27
Q

What is a normal CK?

A

Varies by race/gender - african men have the highest at baseline

28
Q

What disease is CK specific for?

A

It isn’t

29
Q

What does a muscle biopsy look like on a myositis?

A

Inflammation around fibers, scattered necrosis, internal nuclei (should be periopheral in health myocytes), varied sizes of myocyte fibers

30
Q

How should polymyositis be treated?

A

Corticosteroids, Azathioprine, Methotrexage, IVIG, Rituximab - all take a while to work

31
Q

How does Dermatomyositis present?

A

Proximal weakness, dysphagia, heliotrope rash and eczema on the extensor surfaces on joints

32
Q

What does Gottron’s sign suggest?

A

Dermatomyositis

33
Q

What is shawl sign?

A

A rash that appears on sun exposed areas of the skin, suggesting Dermatomyositis

34
Q

What are comborbids with dermatomyositis?

A

Interstitial Lung Disease (anti-Jo1+), Malignancy, Esophageal disease

35
Q

How does dermatomyositis effect kids and adults differently?

A

Dermatomyositis suggests cancer in adults, and GI vasculopathy in kids

36
Q

What part of the immune system drives Polymyositis and how does that compare to Dermantomyositis?

A

Polymyositis = CD8 driven, Dermatomyositis = MAC driven

37
Q

If you see compliment deposition at the edge of a capillary, what should you think and why?

A

Compliment deposition = MAC = Dermatomyositis Leads to poor oxygen exchange to muscles

38
Q

What is perifascicular atrophy?

A

Atrophy of muscle around the edges of capillaries in Dermatomyositis due to compliment deposition inside the edges of capillaries and poor oxygenation

39
Q

How do you treat Dermatomyositis?

A

Corticosteroids + Azathioprine + Methotrexage + IVIg + Rituximab (Same as Polymyositis)

40
Q

Should cancer be surveilled in kids with Dermantomyositis?

A

Nope, they tend to develop GI vasculopathy instead of cancer; adults with Dermatomyositis develop cancer and should be screened

41
Q

What is Inclusion Body Myositis?

A

Distal (not proximal) muscle weakness, asymmetrical, more common in 50+ y/o men

42
Q

Which muscles does Inclusion Body Myositis effect?

A

Effects distal muscles instead of proximal ones like other myopathies, including: Finger flexors, wrist flexors, quadriceps

43
Q

is Inclusion Body Myositis symmetric or asymmetric, and how rapidly does it develop?

A

Asymmetric distal muscle weakness with years of onset

44
Q

What labs suggest Inclusion Body Myositis?

A

Elevated CK, Nerve Conduction Study abnormal

45
Q

How does Inclusion Body Myositis appear on H/E stain?

A

“Rimmed Vacuoles” + low/no inflammation

46
Q

What does “Rimmed Vacuoles” on a stain suggest?

A

Inclusion Body Myositis

47
Q

What is found in Rimmed Vacuoles and how would you prove it?

A

Rimmed Vacuoles contain Amyloid which you can prove with a Congo Red stain Inclusion Body Myositis = Alzheimer’s Disease

48
Q

Should steroids be used in Inclusion Body Myositis?

A

No, Inclusion Body Myositis is driven by Amyloid, not inflammation; use IVIg

49
Q

What is necrotizing myopathy?

A

A type of myopathy with little to inflammation but lots of degeneration and high CK’s, presents acutely

50
Q

What drugs cause necrotizing myopathy?

A

Statins, which lead to an antibody against HMG CoA Reductase, cause statin induced necrotizing myopathy - not the same thing as normal statin myopathy

51
Q

High CK + low inflammation suggests?

A

Necrotizing Myopathy like statin or SRP induced necrotizing myopathy

52
Q

Besides statins, what can cause necrotizing myopathy?

A

SRP (signal reduction particle) and paraneoplastic manifestations

53
Q

How should stating induced necrotizing myopathy be treated?

A

Treat with heavy and long-term immunotherapy

54
Q

What is SRP Myopathy?

A

A necrotizing myopathy caused by SRP with a high prevalence in african american women

55
Q

How should SRP Myopathy be treated?

A

Intense immunotherapy

56
Q

How does SRP Myopathy present?

A

Rapidly (over days to weeks), causing muscle weakness

57
Q

What is this and what would it suggest?

A

The white area on the MRI suggests Myositis in a muscle, and can be used to guide a biopsy for an inflammatory myopathy

58
Q

What would this pathology suggest?

A

Inflammatory cells between myofibers suggests Polymyositis

59
Q

What does this suggest and why?

A

Polymyositis, due to the influx of inlammatory cells, fibers of small size, and occasional internalized nuclei

60
Q

What is this and what does it suggest?

A

Gottron’s Sign due to the rash on the extensor surface of the elbow, suggesting Dermatomyositis

61
Q

What is this and what does it suggest?

A

Shawl rash since it clearly looks like the rash is only on sun exposed surfaces not covered by clothes

Suggets Dermatomyositis

62
Q

What is this and what does it suggest?

A

Perivascular inflammation, suggesting Dermatomyositis

63
Q

What is this and what does it suggest?

A

Rimmed vacuoles, suggesting Inclusion Body Myopathy