Rheumatology Flashcards
What are the main considerations re treatment of dermatomyositis?
acute vs chronic
skin disease vs combined skin and muscle disease
What is the ongoing/chronic treatment for dermatomyositis with skin and muscle disease?
1) high dose oral steroids eg prednisolone 0.75-1.5mg/kg/d for 2-4 weeks then taper (use lowest possible dose)
- steroids reduce morbidity, improve muscle strength and motor function
2) Photoprotection - high protection sunscreen
3) topical steroids - even if treated with systemic corticosteroids
- often help control erythema and pruritis
- otherwise consider topical antipruritics and oral antihistamines OR topical tacrolimus
4) simple moisturisers and emollients
IF underlying malignancy - treat underlying malignancy - improvement or complete resolution of DM has been reported in some cases after successful treatment of underlying malignancy
Consider
Antimalarials eg hydroxycholoroquine
2nd line =
Methotrexate (both muscle and skin)
- steroid-sparing
- more rapid onset of effect than azathioprine
Azathioprine (more muscle disease than skin)
- takes longer than MTX to have effect eg >6mths
3rd line =
Mycophenolate
Ciclosporin - skin and early ILD
4th line =
IVIG
How do you treat patients with dermatomyositis with skin manifestations unresponsive to topical treatments?
Add Hydroxychloroquine
2nd
Methotrexate
Azathioprine
3rd
Mycophenolate
Ciclosporine
recalcitrant disease
IVIG, dapsone, thalidomide
How do you treat acute dermatomyositis?
If severe muscle weakness (e.g., quadriplegia), interstitial lung disease, myocarditis, respiratory failure, severe dysphagia, or other life-threatening complications.
- IV methylpred1g daily for 3-5 days then PO steroids
+
IVIG
What features may predict treatment-resistance to steroid therapy for dermatomyositis and necessitate early adjunctive treatment?
Anti-signal recognition particle (SRP) antibodies in patients with DM are associated with acute severe, treatment-resistant necrotising myositis - IVIG is often required at an early disease stage in these patients; alternative = Rituximab
Patients diagnosed with anti-synthetase syndrome may be corticosteroid-resistant and concomitant use of immunosuppressive drugs (e.g. methotrexate, azathioprine) is required
Presence of anti-melanoma differentiation-associated gene 5 (MDA5) is specific to clinically amyopathic DM, and is strongly associated with rapidly progressive interstitial lung disease. Patients often require treatment with immunosuppressive drugs as well as high-dose systemic corticosteroids from an early disease stage
What are the specific risks of IVIG in dermatomyositis treatment?
acute renal failure
skin rashes
aseptic meningitis
stroke
What is the most sensitive muscle enzyme test for the diagnosis of dermatomyositis?
CK
Other than CK, what other serum markers can elevated in dermatomyositis (incl if CK is normal)?
Serum aldolase
ANA - not specific
Myositis specific antibodies (MSAs) and myositis associated antibodies (MAAs)
- Anti-Mi-2 antibodies
- Anti‐U1 ribonucleoprotein (RNP)
- anti‐Ku
- Anti-Jo-1 and other anti-aminoacyl-tRNA synthetase antibodies (anti-ARS antibodies; including anti‐PL‐7, anti‐PL‐12, anti‐EJ, anti‐OJ, and anti‐KS
What is the significance of finding Anti-transcription intermediary factor 1 gamma in a patient with dermatomyositis?
Strongly assoc with malignancy therefore need extensive search for underlying malignancy
What is the significance and association of Anti-signal recognition particle (SRP) antibodies in dermatomyositis?
Found almost exclusively in polymyositis and assoc with acute severe, treatment-resistant necrotising myositis - need early IVIG +/- Rituximab
What are the key clinical features and antibodies assoc with anti-synthetase syndrome?
ILD, fever, myostitis, polyarthritis, mechanic’s hands, raynaud’s phenomenon
Anti-Jo-1 and other anti-aminoacyl-tRNA synthetase antibodies (anti-ARS antibodies; including anti‐PL‐7, anti‐PL‐12, anti‐EJ, anti‐OJ, and anti‐KS
What is Anti-melanoma differentiation-associated gene 5 (MDA5; also known as CADM‐140) specific for in dermatomyositis?
Clinically amyopathic dermatomyositis (CADM)
It is strongly associated with a rapidly progressive ILD with poor prognosis (need early immunosuppressive tx)
Tender palm papules and diffuse alopecia may be present
Anti-NXP2 is strongly associated with what form of dermatomyositis?
Juvenile DM with a high proportion suffering from cutaneous calcinosis due to dystrophic calcification
Anti-PM-Scl antibodies are often found in patients with?
Overlapping myositis and scleroderma
Describe the ideal muscle biopsy in patients with suspected dermatomyositis?
In symptomatic patients the biopsy should be taken from a weak but not severely atrophied muscle. Quadriceps and deltoid are common sites
Greater yield with open surgical biopsy cf needle biopsy
Greater yield if pre-biopsy EMG or MRI to target biopsy (given possible patchy muscle involvement)
