Inflammatory Myopathies Flashcards
What antibody should be considered in a case of LGMD with negative genetic testing?
HMGCR ab
What inflammatory myopathies are associated with rapid myositis progression over days to weeks?
Viral myositis and immune-mediated necrotizing myopathy (especially anti-SRP antibodies).
What is the heliotrope sign in dermatomyositis?
Periorbital and upper eyelid violaceous discoloration.
What is the Gottron sign?
Erythematous, scaly plaques over the MCP and IP joints.
What is the “V sign” rash?
Sun-exposed rash in the anterior chest seen in DM patients
What is the shawl sign?
Erythematous rash on the posterior neck and shoulders seen in DM.
What is the rash on the lateral thigh called in DM?
Holster sign
What is the relevance of subcutaneous calcifications in dermatomyositis?
“Calcinosis cutis” is associated with anti-NXP-2 antibodies in dermatomyositis (often juvenile).
Nail bed telangiectasias are associated with which antibodies in DM?
Anti – Mi-2 antibodies.
What condition is characterized by a hyperkeratotic eruption over the thumb and radial aspect of fingers?
Mechanic’s hands
What is a prominent feature of dermatomyositis with anti-MDA-5 antibodies?
Interstitial lung disease.
Which myositis conditions are associated with interstitial lung disease?
-Dermatomyositis with anti-MDA-5 antibodies
-Antisynthetase syndrome (Jo 1, PL 7/12)
-Overlap myositis with systemic sclerosis.
What inflammatory myopathies are more likely to cause myocarditis?
IMNM and ICI-related myositis
What inflammatory myositis is associated with pericarditis?
Anti-U1 RNP overlap myositis
Gastrointestinal vasculopathy in juvenile dermatomyositis can lead to what complications?
Intestinal infarcts or hemorrhage.
What inflammatory myopathy is associated with glomerulonephritis?
Anti-U1 RNP antibody overlap myositis.
When can CK be normal in dermatomyositis and anti-synthetase syndrome?
When inflammation is limited to perimysium and fascia with minimal muscle pathology.
What enzyme elevation is diagnostically helpful when CK is normal?
Selective aldolase elevation can be diagnostically helpful.
What myositis shows extreme CK elevations (>20 times normal) if untreated?
Immune-mediated necrotizing myopathy
What is the yield of antibody testing in idiopathic inflammatory myopathies?
About 65% to 70%.
What are the five antibodies related to dermatomyositis?
Anti-NXP-2
Anti-TIF1-γ
Anti-Mi-2
Anti-MDA-5
Anti-SAE.
Which antibodies have the strongest association with malignancy in dermatomyositis?
TIF1-γ antibodies
(Typically mild muscle but significant skin involvement)
Consider cancer screening up to 3 years after dx of myositis (per Kuschlaf 2024 AANEM lecture).
What phenotype is assoicated with NXP-2 abs?
Calcinosis cutis
Peripheral edema
Distal weakness
Higher malignancy risk in adults.
What are the characteristics of Anti-Mi-2 antibody in dermatomyositis?
Severe muscle weakness, acute onset, heliotrope rash, Gottron papules, nail fold pathology, good prognosis.
What complications are associated with anti-MDA-5 antibody syndrome?
Thrombotic complications, skin ulceration, palmar papules, and severe interstitial lung disease.
May have amyopathic dermatomyositis (like Tif1 gamma).
What are characteristic symptoms of SAE abs in dermatomyositis?
Erythematous rashes and severe dysphagia.
Possibly inc cancer risk.
Least common DM abs.
What non-neurologic risk has been associated with dermatomyositis?
An elevated cancer risk.
What is the most common antibody found in antisynthetase syndrome?
Anti-Jo-1 antibody.
What other antibodies are associated with antisynthetase syndrome besides anti-Jo-1.
PL-7, PL-12, OJ, EJ, KS, Zo, Ha.
What is the dominant feature of anti-PL-7 and anti-PL-12 antibody antisynthetase syndrome?
Interstitial lung disease is the dominant feature.
What percentage of immune-mediated necrotizing myopathy cases have specific antibodies detected?
About 65% of cases.
What percentage of DM cases are seronegative?
About 30% (per Kuschlaf AANEM lecture 2024)
Which antibodies are commonly detected in immune-mediated necrotizing myopathy?
Anti-SRP, anti-HMG-CoA reductase IgG, and rarely antimitochondrial M2 antibodies.
What characterizes Anti-SRP antibody syndrome?
Severe weakness, rapid progression, and extremely high CK levels (typically five-digit).
Can have myocarditis and respiratory failure due to diaphragmatic weakness (or ILD).
What can develop within months if SRP IMNM is not treated early?
Muscle fibrosis and fat replacement.
What percentage of patients with anti-HMG-CoA reductase IgG myopathy are statin-naive?
At least one-third of patients are statin-naive.
What subtypes of IMNM are associated with increased cancer risk?
HMGCR and seronegative
What is the pathological manifestation of antimitochondrial antibody-related myositis in over 50% of cases?
Immune-mediated necrotizing myopathy (less commonly presents as a granulomatous myositis). 1/4 patients have primary biliary cirrhosis.
Name myositis associated antibodies (associated with myositis but not specific for it)
U1 RNP
U2 RNP
SSA (most common)
PM Scl
Ku
What percentage of systemic sclerosis/overlap myositis syndrome cases have anti-PM-Scl and anti-Ku antibodies?
60%
What Myositis associated antibodies are associated with dropped head syndrome?
PM-Scl-75 and PM-Scl-100.
What systemic conditions are associated with anti-U1 RNP antibodies?
Glomerulonephritis and pericarditis.
What does MRI show in dermatomyositis?
Edema in subcutaneous tissue, epimysium, perimysium, and patchy muscle edema.
What characterizes immune-mediated necrotizing myopathy on MRI?
Severe diffuse edema and enhancement intramuscularly, with little to no fascial involvement.
What can be seen early on MRI in anti-SRP antibody myopathy?
Fatty replacement and muscle atrophy may occur early in anti-SRP antibody myopathy.
Who should be screened for malignancy in relation to dermatomyositis?
All adults over 40 with dermatomyositis, especially with anti-TIF1-γ and anti-NXP-2 antibodies.
Incidence of cancer in antisynthetase syndrome, anti-SRP myopathy, or overlap myositis?
Low incidence; routine cancer screening not recommended.
What is offered as a first-line treatment in anti-HMG-CoA reductase IgG myopathy?
IVIg
What symptoms are associated with immune checkpoint inhibitor-related myositis?
Proximal limb-girdle weakness, ocular myositis (diplopia, ptosis, resembling myasthenia gravis but neg AchR abs and neg RNS).
How soon after starting immune checkpoint inhibitors do symptoms of myositis typically appear?
Symptoms typically appear within 1 to 2 months after initiation.
Which muscles showed a predilection in immune checkpoint inhibitor-related myositis?
Axial muscles, especially neck extensor muscles.
What did muscle biopsies usually show in ICI related myositis?
Immune-mediated necrotizing myopathy with clusters of necrotic fibers; inflammation was less common.
What was observed about CK levels in ICI related myositis?
CK levels were elevated, yet lower than in other immune-mediated necrotizing myopathy subtypes.
What can be used to treat immune-mediated necrotizing myopathy?
Steroids (IVIG if refractory). If mild symptoms do not need to d/c ICI (not sure I would have to guts to do this).
What percentage of patients with COVID report myalgia?
50% of patients report myalgia.
What percentage of patients show asymptomatic CK elevations in COVID?
16% to 33% show asymptomatic CK elevations.
What are the three clinical phenotypes of myopathy associated with COVID-19?
Rhabdomyolysis
Classic dermatomyositis
Isolated paraspinal myositis.
What is mixed connective tissue disease (MCTD)?
Type of overlap syndrome.
Main features of at least two overlapping connective tissue diseases including:
SLE, systemic sclerosis, rheumatoid arthritis, myositis.
Defined by the presence of anti-U1 RNP antibodies and Raynaud’s phenomenon
What antibody is associated with immune mediated Rippling Muscle Disease?
Anti Cavin 4 abs
All should have percussion induced muscle rippling.
What ab is seen with IBM?
NT5C1A
Seen in about 40-60% of IBM (no difference in seropostive or seronegative clinically)
Can see false + in other inflammatory myopathies, SLE/Sjogren’s, MND, VCP, and even in normal volunteers (per Kuschlaf AANEM 2024 lecture)
