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Dermatology Board Prep > DERM (17) Rheumatologic Dermatology > Dermatomyositis > Flashcards

Dermatomyositis Flashcards

1
Q

What other connective tissue diseases can dermatomyositis overlap with?

A

Scleroderma/systemic sclerosis (most common)>>SLE, Sjogren’s, RA

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2
Q

Epidemiology of dermatomyositis?

A

Bimodal age distribution (i) Juvenile DM: no increased risk of internal disease, Does have calcinosis cutis and small vessel vasculitis II Adult DM: a/w occult malignancy (~25% of time.

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3
Q

Most commonly associated tumors with DM in adults?

A

ovarian and colon, nasopharyngeal in SE asians

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4
Q

Pathogenesis of DM?

A

Environmental factors (malignancy, UV radiation, viral infection) trigger an immune response in susceptible people

Muscle inflammation –> cell-mediated immunity (CD8+ T-cells attack muscles)

Cutaneous eruption –> humoral immunity

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5
Q

In what % of patients are ANA + in DM?

A

60% of pts

  • Some target DM antigens are in the cytoplasm (Synthetase and MDA5)
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6
Q

Clinical features of DM?

A

Gottron’s papules Violaceous hue of upper eyelids w/ periorbital edema - heliotrope sign Naifold telangiectasias –> ragged cuticles, proximal nail fold with dilated capillary loops alternate with vessel dropout.

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7
Q

Is DM pruritic?

A

Yes! unlike LE and other papulosquamous diseases, DM is very pruritic and can cause pt’s severe distress with this.

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8
Q

Common DM cutaneous manifestations?

A

Heliotrope sign, eyelid edema, gottron papules, gottron sign, photo distributed poikiloderma, scalp poikiloderma and scaling, non-scarring alopecia, nail-fold changes (ragged cuticles, cuticular hypertrophy, nail-fold telangiectasias), Holster sign (poikiloderma of the lateral thighs), psoriasiform lesions, calcinosis cutis

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9
Q

Myositis workup for DM?

A

-Proximal extensor muscle weakness (shoulder/hips) -Serum CK and aldolase, repeat q2-3 months -U/s or MRI of proximal muscle -Electromyography -Muscle bx

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10
Q

What is the definition of amyopathic DM?

A

Amyopathic DM is when muscle enzymes are normal w/ no muscle weakness for >2 years

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11
Q

Systemic workup for DM?

A

-Check for overlapping syndromes (i.e. scleroderma) -Check for interstitial lung dz (PFTs - DLCO or high-resolution CT) - affect 15-30% of pts -ECG

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12
Q

Evaluation for new DM/Amyopathic DM?

A

-Check at baseline and repeat annually x 2-3 years -Malignancy screen: breast and pelvic (W), testicular and prostate (M), rectal/colon (M/W)

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13
Q

Histology of DM?

A
  • Epidermal atrophy - vacuolar interface dermatitis [sparse lymphocytic infiltrate] - Dermal mucin deposition - Gottron’s papules show a lichenoid infiltrate but have acanthosis rather than epidermal atrophy
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14
Q

What are the Anti-aminoacyl-tRNA synthetase autoantibodies and what is their significance?

A

Anti-Jo-1 (histidyl) and anti-PL-7 (threonyl) These are associated with antisynthetase syndrome (fever, polyarthritis, ‘mechanic’s hands,’ Raynaud’s phenomenon, interstitial lung disease) -Present in up to 20% of adult patients

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15
Q

Significance of the Anti-Mi-2 antibody in DM?

A

Most specific for classic DM, milder muscle disease, good response to treatment, present in up to 10-15% of patients

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16
Q

What is the most specific antibody for classic DM?

A

Anti-Mi-2

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17
Q

What is the signifcance of the Anti-TIF1-gamma (ANTI-155/140) antibody?

A

Severe cutaneous DM; malignancy-associated; amyopathic

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18
Q

What antibody is a/w rapidly progressive interstitial lung disease?

A

Anti-MDA5 (CADM-140)

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19
Q

What is the clinical significance of the Anti-MDA5 antibody?

A

Clinically amyopathic CM -Characteristic mucocutaneous findings, including tender palmar papules, ulcerations on the knuckles/elbows, oral/gum pain, diffuse alopecia -Rapidly progressing interstitial lung disease

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20
Q

What is the significance of the Anti-NXP-2 (anti-p140) antibody?

A

Juvenile -onset classic DM w/ calcinosis cutis

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21
Q

What antibody is a/w juvenile-onset classic DM?

A

Anti-NXP-2 (anti-p140) antibody

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22
Q

What is the significance of the Anti-SAE antibody

A

Clinically amyopathic DM that may progress to myositis and dysphagia. -ILD is uncommon

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23
Q

How do you treat the myositis of DM?

A

Initiate steroids at 1mg/kg/day + steroid-sparing agent (i.e. MMF, weekly MTX) the taper steroids by 1/2 stargin dose by 6 months –> long taper over 2 years.

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24
Q

How do you treat the cutaneous eruption of DM?

A

Topical CS + anitmalarias + sun protenction

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25
Q

Risk of Hydroxychloroquine in patients with DM?

A

Still the first line but there is an increased risk of a cutaneous drug reaction to HCQ in DM patis, may tolerate chloroquine -2nd line is MTX, MMF, IVIG for refractory cutaneous DM –> maybe rituximab as an emerging treatment option.

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26
Q

What drugs should be avoided in DM?

A

TNF-a because of drug-induced or drug-exacerbated DM

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27
Q

How do you treat the calcinosis cutis in DM?

A

CCB +/- surgical excision

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28
Q

What is the genetic predisposition in juvenile DM?

A

TNF-a308A –> capillary occlusion (increased thrombospondin-1)

29
Q

What is the Brundsting variant of DM?

A

This is the classic juvenile DM (calcinosis cutis, less ulceration, less vasculopathy, steroid-responsive)

30
Q

What is the Banker variant of DM?

A

<10%, rare, ulcerative/vasculopathic, severe myositis, recalcitrant to steroids, poor prognosis

31
Q

Most common cause of drug-induced DM?

A

Hydroxyurea >> statins

32
Q

What is the difference between Hydroxyurea-induced vs non-hydroxyurea-induced DM?

A
  • Hydroxyurea-induced: long latency period (60 months, no myositis)
  • Non-hydroxyurea induced: short latency (2 months, 80% with myositis, more ANA positivity).
33
Q

Significance of vasculitis in DM?

A

Bad prognostic indicator. Ulcerations, widespread calcinosis, poor response to tx

34
Q

What is the character of the risk of malignancy in DM?

A

Ovarian and GI (Colon>>others) most common.

  • Risk of cancer returns to normal after 5 years of DM onset EXCEPT pancreatic and colorectal CA
35
Q

For which cancers does the risk of occurrence not return to baseline after 5 years?

A

Pancreatic and colorectal

36
Q

What are the most common causes of death in adults with DM?

A

Malignancy, ischemic heart dz, pulmonary dz.

37
Q

What percentage of adults diagnosed with dermatomyositis have simultaneous neoplasm?

A

25%

38
Q

What percentage of patients with dermatomyositis have the amyopathic form?

A

20%

39
Q

Why is the ANA often negative in dermatomyositis?

A

Because the anti-synthetase and MDA5 antibodies are targeted against cytoplasmic proteins

40
Q

What causes the shape of the shawl sign and the v-neck sign?

A

These are relatively sun-exposed areas and the sun exposure makes it worse

41
Q

What type of UV exposure triggers dermatomyositis more?

A

UVA

42
Q

Can visible light affect dermatomyositis?

A

There is some evidence that even visible light spectrum radiation can worsen the rash in dermatomyositis.

43
Q

What muscles are most commonly affected?

A

Proximal extensor muscles: quadriceps and triceps

In NXP-2 related DM, distal muscles can be affected

44
Q

What is the target of Mi-2 autoantibody in dermatomyositis?

A

Nuclear DNA helicase involved in DNA transcription

45
Q

What is the clinical significance of the anti Mi-2 autoantibody?

A

Often a classic appearing DM, heliotrope rash, shawl sign, myositis of proximal muscles, gottran’s papules etc. Often responds well to treatment

46
Q

What is the target of TIF-1 autoantibody in dermatomyositis?

A

TIF-1 is a tumor suppressor/transcriptional corepressor. Three subtypes alpha, beta, gamma, which have their own autoantibodies.

47
Q

Clinical significance of TIF-1 autoantibodies?

A

The biggest thing is a strong association with underlying malignancy. Positive predictive value is estimated at 58% and negative at 95%. The autoantibody is thought to be generated from the anti-tumor immune response

  • Also associated with severe photosensitive disease, heliotrope rash, v sign, gottron papules, palmar hyperkeratosis, psoriasiform plaques, ovoid palatal patches and atrophic hypopigmented patches w/ overlying telangiectasias, hypomyopathic disease, GI involvement, and lack of ILD, Raynaud, and arthritis
48
Q

What is the most common cause of drug-induced DM?

A

Hydroxyurea (>50%)

49
Q

What is the target of MDA5 autoantibody in dermatomyositis?

A

RNA-specific helicase involved in antiviral immune responses

50
Q

Clinical associations with anti MDA5 dermatomyositis?

A
  • Clinically amyopathic disease
  • More common in Asian populations
  • Increased risk of ILD and rapidly evolving ILD
  • Associated w/ cutaneous ulceration (often at Gottran’s papules, nail folds), painful palmar papules (inverse Gottran’s papules), and panniculitis. All signs of vasculopathy
51
Q

Most common autoantibodies associated with juvenile dermatomyositis?

A

Anti-NXP2, Anti-MDA5, Anti-TIF1

52
Q

What is the target of NXP-2 autoantibody in dermatomyositis?

A

NXP-2 is a protein that regulates transcription and RNA metabolism.

53
Q

Clinical associations with NXP-2?

A
  • Common antibody in juvenile dermatomyositis
  • Classic cutaneous findings + calcinosis (children>adults)
  • Can be associated with severe myopathy leading to contractures (Juvenile form)
  • GI bleeding (juvenile form, 2/2 bad vascular disease)
  • Juvenile form w/ this autoantibody does not portend to increased cancer risk
54
Q

What is the target of SAE autoantibody in dermatomyositis?

A

SAE, small nuclear enzyme involved in posttranslational modification of proteins

55
Q

Clinical associations of SAE autoantibody?

A

Starts w/ severe cutaneous dz and minimal myopathy and then progressives to more severe myopathy. Can lead to severe dysphagia.

  • Systemic sx’s like fever, weight loss
  • Predictive of hydroxychloroquine triggered rash
56
Q

What are the different anti-synthetase autoantibodies?

A

Includes: Anti Jo-1 (histidyl), anti-PL7 (alanyl), Anti-PL-12 (glycyl), Anti-EJ (isoleucyl), anti-OJ (isoluecyl), anti-KS (asparginyl), anti-Zo (phenylalnyl), and anti -YRS/HA(tyrosyl)

57
Q

What is the clinical implications of positive anti-synthetase autoantibodies?

A

Myositis with ILD, Raynaud’s, Gottran’s papules, “mechanics hands”, more severe ILD and poorer prognosis

“Anti-synthetase syndrome”

58
Q

Clinical associations of Anti-SRP antibodies?

A

Sudden, severe, progressive muscle weakness that can include the cardiac muscle and esophagus/pharynx (dysphagia). tends to be treatment-resistant and carries no increased risk of malignancy

“Necrotizing myopathy”

59
Q

What components tend to be more prevalent in the DIF in DM?

A

Less intense lupus band area positivity

  • Tends to have more C5-9 complement > C3 more IgM
60
Q

Clinical associations of anti-HMGCR dermatomyositis?

A

Increased risk of malignancy, statin-induced myopathy

61
Q

Clinical associations with Anti-CN1A dermatomyositis?

A

Progressive weakness and functional impairment in older patients (>50 y/o)

62
Q

What gene mutation can be associated with juvenile DM?

A

TNF-alpha308A

  • Leads to increased thrombospondin-1 (potent anti-angiogenic factor) –> increased occlusion of capillaries
63
Q

What are the main drugs associated with drug-induced DM?

A

Hydroxyurea (>50%), statins, D-penicillamine, cyclophosphamide, BCG vaccine, TNF-alpha inhibitors

64
Q

What is the clinical presentation of muscle involvement in DM?

A

Usually symmetric, slowly progressive weakness of the (extensors>flexors)

  • Not painful ask about difficulty walking up stairs, standing up from sitting position, or brushing hair
65
Q

Why is checking neck flexor strength important?

A

Can signal more advanced dz, wil potentially impending head drop, dysphagia, or diaphragm involvement

66
Q

What is the significance of the Anti-Ku antibody/

A

Tend to be associated with polymyositis overlapping with either SLE, Sjogren syndrome, or scleroderma

67
Q

What is the significance of anti-PM-1 (PM/Scl)?

A

Associated with DM/PM + scleroderma overlap dz

68
Q

What is the difference in the clinical presentation of hydroxyurea-induced vs non-hydroxyurea-induced DM?

A

Hydroxyurea-induced DM: Longer latency (avg =60 months) after drug initiation. NO MYOSITIS, 16% w/ + ANA

Non-hydroxyurea-induced DM: Occurs within 2 months of drug initiation; 80% have myositis; ANA usually + in 54%

Both have classic skin findings and resolve 1-2 months after stopping drug

69
Q

What treatment should be avoided if a patient is found to have cancer and needs a lymph node biopsy?

A

Don’t start prednisone/steroids! This alters the architecture of the nodes

DERM (17) Rheumatologic Dermatology (5 decks)

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