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Rheum/Musculoskeletal/Derm Week 2 > Inflammatory Myopathies/PMR > Flashcards

Inflammatory Myopathies/PMR Flashcards

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1
Q

Inflammatory myopathies are systemic diseases involving multiple organs. What are some types?

A
  • Dermatomyositis
  • Antsynthetase Syndrome
  • Amyopathic Dermatomyositis
  • Juvenile Dermatomyositis
  • Inclusion Body Myositis
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2
Q

What is antisynthetase syndrome?

A

As a syndrome, this condition is poorly defined. Diagnostic criteria require one or more antisynthetase antibodies (which target tRNA synthetase enzymes), and one or more of the following three clinical features: interstitial lung disease, inflammatory myopathy, and inflammatory polyarthritis affecting small joints symmetrically. Other supporting features may include fever, Raynaud’s phenomenon and “mechanics hands”-thick, cracked skin usually on the palms and radial surfaces of the digits.

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3
Q

What is Amyopathic Dermatomyositis? What is a major risk in these patients?

A

disease in which patients have DM type rash confirmed by skin biopsy, BUT no myositis (CPK normal and muscle function normal) but may develop myositis late and are at risk for severe ILD

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4
Q

What is Juvenile Dermatomyositis? Common triad? Cause?

A

rare disease with peak onset at age 6 and 11 years with features commonly seen in adult DM (except in JDM the rash pain is WAY more severe); 30% to 70% have calcinosis (below), cutaneous ulceration and lipodystrophy.

The disease is usually triggered by a condition that causes immune system activity that does not stop as it should, but the trigger is almost certainly not the cause in most cases. Common triggers include immunizations, infections, injuries, and sunburn.

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5
Q

What is Inclusion Body Myositis? Patients?

A

IBM has sporadic and familial hereditary forms, characteristic histological features including sarcoplasmic and nuclear inclusions and rimmed vacuoles, and an insidious onset of muscle weakness over months to years

common in older men (50+) and localizes in thigh muscles and finger flexors (resistant to much treatment)

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6
Q

The insidious onset of muscle weakness seen in IBM is confined to where?

A

localized predominantly to the thigh muscle and finger flexors but eventually is widespread and both proximal and distal

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7
Q

T or F. IBM is resistant to glucocorticoid treatment

A

T. So if you are considering this and PM (which present very similarly, the lack of efficiacy of prednisone suggests this)

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8
Q

Patient population for IBM?

A

occurs mostly in men over 50 yrs.

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9
Q

What are some characteristic features of dermatomyositis skin changes?

A
  • Gottron’s papules
  • Heliotrope rash
  • Gottron’s sign of knees and elbows
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10
Q

How can SLE be differentiated from DM?

A

Erythematous rashes on the hand in dermatomyositis and systemic lupus erythematosus. A, Note the changes on the knuckles and dorsum of the hand in dermatomyositis (Gottron’s sign). B, Rash is absent on the knuckles but present on the phalanges in lupus. C, Capillary nail-fold changes in dermatomyositis.

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11
Q

What are some other possible sign changes in DM?

A

A, Linear erythema. B, Scalp rash. C, V-like sign. D, Shawl sign.

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12
Q

What do these images show?

A

Appearance of “Mechanics Hands” Anti-Synthetase Syndrome

Mechanic’s hands in a white (A) and a black (B) patient. Note the characteristic skin changes on the lateral side of the fingers.

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13
Q

What is the annual incidence of all inflammatory myopathies [dermatomyositis (DM), polymyositis (PM) and inclusion body myositis (IBM)]?

A

estimated to be 10 per million individuals.

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14
Q

When does PM present?

A

usually in late teens OR older with a mean age at onset being 50-60 years (biphasic) MOSTLY IN WOMEN LIKE DM

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15
Q

When does DM present? IBM?

A

DM shows two peaks-5 to 15 years and 45-65 years; mostly in WOMEN (very common to present after pregnancy- could be an immune rxn to lingering fetal antigens)

IBM is commonly seen in MALES older than 50 years

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16
Q

Inflammatory myopathies (from 11 to 40% of all myositis) can occur in association with other autoimmune connective tissue diseases. Name some

A

Scleroderma, SLE, rheumatoid arthritis, Sjogren’s syndrome, polyarteritis nodosa, and sarcoidosis.

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17
Q

12% of myositis cases are associated with what?

A

a malignancy (breast CA, adenocarcinoma) and detected in the first year of diagnosis of myositis; majority have DM (81%), PM is 19%.

Thus, DM and PM are essentially paraneoplastic syndromes in these cases (if the cancer is pre-existent, removal of the cancer usually results in remission of the dermatomyositis)

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18
Q

Diagnosis?

A

Dermatomyositis - a heliotrope rash is NOT seen in polymyositis or MCTD

In inclusion body myositis, there is both proximal AND distal muscle weakness (and is usually asymmtric)

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19
Q

Dx?

A

Inclusion body myositis, dont see weak finger flexors in polymyositis or dermatomyositis

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20
Q

What is a very common complication of IBM?

A

Dysphagia is a progressive condition in about 50-75% of patients with IBM and often leads to death from aspiration pneumonia.

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21
Q

Arthritis occurs commonly with inflammatory myopathies. What Abs is it commonly associated with?

A

anti-Jo-1 ABs against histidyl-tRNA synthetase

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22
Q

Diarrhea is often a symptom of inflammatory myopathies. Why?

A

sphincter ani can be impaired (and other straited muscle)

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23
Q

How can you distinguish PM vs. DM histo?

A

PM- endomysial inflammation (below)

DM- perimysal inflammation

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24
Q

tRNA synthetase Abs are associated with what?

A

may have arthritis in addition to myositis, fevers, ILD and the “mechanic’s hands” so named because of the thickening of the palms of the hand

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25
Q

Mi-2 ABs are associated with what? HLA type?

A

DM with Gottron’s papules, heliotrope rash, V sign, and the shawl sign

DR7

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26
Q

What HLA groups are assoicated with aminoacyl-tRNA synthetase ABs?

A

HLA-DQA1*0501

27
Q

What HLA groups are assoicated with anti-SRP ABs? Clinical associations?

A

DR5

associated with severe muscle weakness that comes on very rapidly, muscle aches, and cardiac involvement.

28
Q

What HLA groups are assoicated with anti-PM/Scl?

A

DR3

29
Q

Note about the presence of anti-PM/Scl ABs

A

these patients typically have a characteristic overlap syndrome with features of limited scleroderma with mild muscle disease, and prominent arthritis,

respond well to therapy

30
Q

The composition of cellular infiltrates can be a useful diagnostic in inflammatory myopathies. What are the infiltrates like in DM?

A

perivascular, often in perimysial areas and is made up of CD4 T cells, macrophages, and dendritic cells with B cells

31
Q

What are the infiltrates like in PM or IBM?

A

mostly CD8 T cells and macrophages and are surrounding predominantly endomysial with mononuclear inflammatory cells and often invade non-necrotic muscle fibers

the CD8 lymphocytes can recognize MHC class I muscle fibers and may mediate muscle fiber damage

32
Q

How muscle damaged in polymyositis?

A

probably mediated by complement, Ab activation, and cytokines that can endothelial damage leading to hypoxia, capillary loss and eventually loss of skeletal muscle fiber AND

cytokines and CD8 T cells binding to MHC class I and causing ER stress and myofiber damage leading to loss of muscle fibers

33
Q

Describe inclusion body myositis. Patient population?

A
  1. Mostly proximal muscle weakness in lower extremities with also distal muscle supplying upper extremities.
  2. Poor response to corticosteroids
  3. Seen mostly in older men
34
Q

T or F. CPK should be elevated in inflammatory myopathies

A

T. Except amyopathic DM

can be huge increases!! up to 1000s and 10ks

35
Q

How are inflammatory myopathies treated?

A

start with high-dose prednisone quickly to subside weakness and drop CPK and then you want to add a steroid-sparing agent such as methotrexate or azathioprine or MM

if no response, go to IVIG (IBM doesnt respond well to any therapy)

36
Q

Dx.

A

Polymyalgia rheumatica

SLE- cant be (ANA was negative)

Rheumatoid Arthritis- cant be (RF neg)

Osteoarthritis- really doesnt present in the shoulder

37
Q

What are some symptoms of giant cell arteritis that aren’t present in PMR?

A

jaw claudication, temporal artery tenderness, HA, visual loss, and evidence of noncranial ischemia such as arm claudicaiton or cerebral ischemia

PMR has a low yield of temporal artery biopsy

constitiutional symptoms (fever, fatigue, weight loss) will be present

38
Q

T or F. Patients under 70, with no headahce or jaw claudicaiton, and with normal temporaly arteries have a very low risk of vasculitis

A

T.

39
Q

Note about PMR vs. GCA

A

PMR occurs in about 50% of patients with GCA, while 15% of PMR patients develop GCA.

40
Q

How does PMR present? Suspected causes? HLA type?

A

PMR occurs in patients over age 50 and is characterized by stiffness and pain in shoulder and hip musculature (mostly in the morning). Patients often develop profound disuse atrophy of muscles and complain of weakness, giving rise to the suspicion of polymyositis.The ESR is often elevated.

Infection: The viruses thought to be involved include the adenovirus, which causes respiratory infections; the human parvovirus B19, an infection that affects children; and the human parainfluenza virus

DR4

41
Q

MRI has confirmed that PMR involves what?

A

inflammation of extrarticular synovial structures. As an example, MRI of the hands and feet of those with PMR frequently demonstrate inflammation of the ten­don sheaths. In addition, shoulder MRI reveals subacromial and subdeltoid bursitis in almost all patients with active PMR.

42
Q

What is a common pathology that occurs in a subset (10-15%) of PMR patients?

A

Tenosynovitis may also cause carpal tunnel syndrome

43
Q

Another rare condition associated with PMR?

A

Some patients with PMR develop swelling and pitting edema over the hands, wrists, ankles, and top of the feet. The edema usually occurs with other signs of polymyalgia rheumatica but can be the presenting symptom. It appears to represent tenosynovitis and synovitis in regional structures. This syndrome represents a subset of patients with PMR.

Typically, they do not evolve into rheumatoid arthritis.

44
Q

Dx.

A

Giant cell arteritis/temporal arteritis

ALT, AST, and ALP can be elevated (will return to normal with steroids)

45
Q

What is GCA/temporal arteritis?

A

·Necrotizing inflammation of large sized arteries originating from the arch of the aorta

  1. Is associated with granulomas
  2. Is not associated with a glomerulonephritis
46
Q

How does GSA/TA occur?

A

IFN-y production follows antigen recognition in the adventitia of a vessel, leading to specialization of macrophages, formation of giant cells, and subsequent production of MMPs, and growth and angiogenic factors.

Tissue destruction and repair/modeling then promote matrix degradation (arterial wall destruction) and occlusive intimal hyperplasia, respectively.

47
Q

How can GCA/TA affect the lungs/URT?

A

About 10% of these patients can have upper respiratory symptoms including nonproductive cough and SEVERE sore throat. Repeat negative throat cultures and absence of infiltrate on CXR are consistent

48
Q

What is a potential, very serious complication of GCA?

A

aortic aneurysm, monitor closely.

49
Q

Why does/can aortic aneurysm occur with GCA?

A

one of two mechanisms:

1) chronic or late recrduescent aortitis causing elastin and collagen disruption
2) mechanical stress on an aortic wall that was weakened in the early active phase of the disease

50
Q

How can an aortic aneurysm be detected?

A

widening of the mediastinum on CXR

51
Q
A
52
Q

What is an ESR (sed rate) test?

A

simple and cheap test that measures the rate at which RBC fall through plasma and is an indirect measure of fibrinogen levels (influenced by RBC properties)

53
Q

How is temporal arteritis diagnosed?

A

·Diagnosis is by temporal artery biopsy

54
Q

Pathology of temporal arteritis?

A

Pathology early in disease reveals collections of lymphocytes in region of internal or external elastic membrane or adventitia. Later there is necrosis of portions of the arterial wall and granuloma formation with multinucleated giant cells, histocytes, plasma cells and fibroblasts. Thrombosis may occur. The inflammation is most marked near the elastic membrane which is typically destroyed or interrupted

55
Q

How is PMR treated?

A

prednisone up to 20mg/day for 7 days

then check response:

if good, diagnosis supported and continue to monitor for GCA

if bad, increase prednisone to 30mg/day for 7 days

then check response,

if bad, reject PMR diagnosis

56
Q

How is TA treated?

A

Corticosteroids in high doses (1mg/kg/day of prednisone or equivalent)

It is critical to begin treatment with steroids as soon as diagnosis is suspected otherwise your patient may go blind permanently. One should treat and make arrangements for the temporal artery biopsy but do not wait for the biopsy to be done or results to be back before starting treatment

Prognosis is good with treatment. However, blindness is irreversible.

57
Q

What is this?

A

Inclusion body myositis

58
Q
A
59
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A
60
Q
A
61
Q
A

Want to see transmural inflammation (dont need to see giant cells) and the internal elastic lamina SHOULD BE BROKEN

62
Q
A
63
Q

Presentation of polymyositis

A

Diagnosis is fourfold, history and physical examination, elevation of creatine kinase, electromyograph (EMG) alteration, and a positive muscle biopsy.

The hallmark clinical features of polymyositis is proximal muscle weakness, with less important findings being muscle pain and dysphagia. Cardiac and pulmonary findings will be present in approximately 25% of cases of patients with polymyositis.

64
Q

PM vs. IBM

A

Sporadic inclusion body myositis (sIBM): IBM is often confused with (misdiagnosed as) polymyositis or dermatomyositis that does not respond to treatment is likely IBM. sIBM comes on over months to years; polymyositis comes on over weeks to months. Polymyositis tends to respond well to treatment, at least initially; IBM does not.

Rheum/Musculoskeletal/Derm Week 2 (12 decks)

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