Rheumatology Flashcards
What do urate crystals look like under polarised light?
They are yellow needle like structures when held parallel to the lights source. When held perpendicular to the light, they turn blue. This is said to be negative birefrigence.
What do calcium pyrophosphate crystals look like under polarised light?
They are blunt rods. When parallel to the light source, they appear blue. When perpendicular, they appear yellow. They therefore demonstrate positive birefringence.
What is Lofgren sydnrome?
Triad of acute sarcoid arthritis, hilar adenopathy and erythema nodosum. Only 10% of patients with sarcoidosis devlop with the triad of Lofgren syndrome. Classically, the polyarthropathy involves the ankles >90% of the time, often bilaterally, followed by other larger joints in the lower extremities.
What treatment is recommended as secondary prophylaxis in patients with APLS and SLE?
Hydroxychloroquine
What is the anticoagulation of choice for patients with a history of venous thrombosis and anti-phospholipid syndreome?
Warfarin. There is some controversy over what should be done in the case of arterial thrombosis. Some advocate for aspirin and warfarin.
How should catastrophic aPLS be managed?
Combinations of anticoagulation, high dose steroids, plasma exchange and IVIG have all been employed in case series.
What does alternating buttock pain suggest?
SIJ inflammaotry disease
What percentage of patietns with SLE have a positive ANA?
95%. The titre is however not useful for anything (disease monitoring, sepctrum of involvement and so on)
What diseases are associated with an increased risk of calcium pyrophophosphate disease?
Hypothyroidism, hyperparathyroidism, haemochromatosis, hypomagnesaemia and hyphosphataemia, and familial hypocalciuruic hypercalcaemia.
What are the clinical features of dermatomyositis? Not including inclusion body myositis or anti-synthetase syndrome which have their own specific findings.
Photosensitive rashes: violaceous eruptsion on the knuckles (Gottron’s rash), blue/purple rash round the eyes, face, back and shoulders (shawl sign).
Muscles: subacute proximal, symmetrical muscle weakness. Distal muscles are only present later in disease in 10-20% of patients.
Other: dilated capillary loops at the nailfolds.
What autoantibodies are typically associated with dermatomyositis? (excluding the anti-synthetase abs)
Most are directed agains cytoplasmic RNA-protein complexes. The most commonly associated anitbody is anti-transcription intermediary factor 1 gamma (TIF1 gamma). It is, however, also strongly associated with cancer and so careful malignancy investigation should follow. Anti-Mi-2 (helicase) abs are detected in about 10% of patients, and then antiU1 riboneucleoprotiein (RNP) and anti-Ku are found in overlap syndreomes that present similarly to anti-Mi-2 positive DM. Anti-SAE antibody is found in 5-10% of patients and is associated with a high prevalence of dysphagia, and skin manifestations precede muscle symptoms. Anti-nxp-2 abs are also possible, but are often associated with malignancy or are seen in juvenile disease.
Which antibody is highly specific for immune-mediated necrotising myositis?
Anti-signal recognition particle (SRP).
Are CRP and ESR elevated in dermatomyositis?
They are often normal or only slightly elevated.
Is a positive myositis ab required to make a diagnosis of dermatomyostitis?
No. They are positive in 45-85% of cases, but are used to prognosticate rather than diagnose.
What are the antibodies associated with anti-synthetase syndrome?
Mostly associated with tRNA. Anti-Jo-1, anti-ARS abs including: anti-PL-7, anti-PL-12, anti-EJ, anti-OJ, anti-Zo, anti-Ha and anti-KS.
Which antibody is associated specifically with amyotrophic dermatomyositis?
Anti-MDA5 (aka anti-CADM-140). It is stronly associated with progressive intersitial lung disease with a poor prognosis. Diffuse alopecia is also seen with this s well as arthritis.
How does antisynthetase syndrome usually present?
Prominent arthritis, interstitial lung disease, fever, mechanic’s hands, proximal myopathy, rey
What three disease should be excluded before settling on a diagnosis of polymyositis in a patient who presens with inflammatory, symmetrical muscle disease?
Must exlcuded other myopathies without rash. Therefore, must exclude hypothyroidism, immune-mediated necrotizing myopathy and inclusion body myositis.
Which systemic inflmmatory diseases may incolude myositis as a manifestation?
SLE, mixed connective tissue disease, scleroderma and less often: Sjogrens’ syndreom and RA.
What is the classic clinic presentation of inclusion-body myositis?
Proximal lower limb and distal upper limb weakness. Specifically, weakness in the deep flexors of the forearm. It classically effects men. It is also sometimes associated with dysphagia.
What clinical feature are the anti-nxp-2 myositis antibodies uniquely associated with?
Skin calcifications
What liver enzymes can be released from skeletal muscle in the setting of active immune myositis?
AST and ALT (AST > ALT)
What autoantibodies are seen 50% of inclusion body myositis patients?
Anti-cytosolic 5’-nucletidase 1a (anti-cN1A)
Which dermatomyositis ab is most often associated with dysphagia?
Anti-SAE
What are the classic findings on muscle biopsy for patients with inclusion body myositis?
CD8+ve infiltrates, rimmed vacuoles (note though, these are absent in 20-30% of patients with inclusion body myositis), amyloid deposits with congo red staining (sometimes seen), p62/TDP-43 protein aggregates (much more common than amyloid). Under EM, inclusions are shown to contain 15-18nm tubolfilaments not present in any other inflammatory myopathy. Some sources talk about ‘ragged-red/blue fibres’ being important (I think this ithe p62/TDP-43 protein aggregates).
Which inflammatory myopathies are most commonly assocaited with interstiail lung disease?
Antisynthetase syndrome, amyopathic dermatomyositis (including anti-MDA5 disease- rapidly progressive ILD), and overlap syndromes with connective tissue disease.
What is antibody the defines mixed connective tissue disease?
Anti-U1 ribonucleoprotein (anti-U1RNP)
What are the typical features of mixed connective tissue disease?
Swollen hands, synovitis, myositis, Raynaud phenomenon and acrosclerosis.
What people are typically diagnosed with mixed connective tissue disease?
Women, adolescence and early 20s, HLA-DRB10401.
What complication, similar to scleroderma Scl-70, is the major cause of mortality in patients with mixed connective tissue disease?
Interstitial lung disease and pulmonary hypertension
Second to lung disease, what is the most impactful contribution to mortality in patients with mixed connective tissue disease?
Cardiac and pericardaial involvement. Responsible for about 20% of mortality in MCTD patients.
What two organ systems does mixed connective tissue spare that diffuse scleroderma and SLE typically damage?
Kidneys and central nervous system (except for sensuroneural hearing loss)
Which two dermatomyositis antibodies are most commonly associated with cancer?
Anti-NXP-2 (when it occurs in adults) and anti-TIF1gamma.
What is febuxostat?
A nonpurine inhibitor of xanthine oxireducatse (allopurinol is a purine inhibtior of XO). It is reserved as a second line agent in the treatment of gout for patients who can’t tolerate allopurinol. It still increases the concentration of azathioprine metabolites. It worsens cardiovascular and all cause mortality in patients when compared with gout.
What is the major downside of febuxostat compared with allopurinol?
Worsens cardiovascular and all cause mortality.
What is Felty disease?
An extra-articular manifestation of rheumatoid arthritis associated with splenomegaly (with associated thrombocytopoenia), anaemia, and neutropoenia.
