MSK + Skin Flashcards
Presentation of psoriatic arothropy
Patterns
symmetric polyarthritis
very similar to rheumatoid arthritis
30-40% of cases, most common type
asymmetrical oligoarthritis: typically affects hands and feet (20-30%)
until recently it was thought asymmetrical oligoarthritis was the most common type, based on data from the original 1973 Moll and Wright paper. Please see the link for a comparison of more recent studies
sacroiliitis
DIP joint disease (10%)
arthritis mutilans (severe deformity fingers/hand, ‘telescoping fingers’)
psoriatic skin lesions
periarticular disease - tenosynovitis and soft tissue inflammation resulting in:
enthesitis: inflammation at the site of tendon and ligament insertion e.g. Achilles tendonitis, plantar fascitis
tenosynovitis: typically of the flexor tendons of the hands
dactylitis: diffuse swelling of a finger or toe
nail changes
pitting
onycholysis
X ray findings for psoriatic arothropy
often have the unusual combination of coexistence of erosive changes and new bone formation
periostitis
‘pencil-in-cup’ appearance
Management of psoriatic arothropy
should be managed by a rheumatologist
treatment is similar to that of rheumatoid arthritis (RA). However, the following differences are noted:
mild peripheral arthritis/mild axial disease may be treated with ‘just’ an NSAID, rather than all patients being on disease-modifying therapy as with RA
if more moderate/severe disease then methotrexate is typically used as in RA
use of monoclonal antibodies such as ustekinumab (targets both IL-12 and IL-23) and secukinumab (targets IL-17)
apremilast: phosphodiesterase type-4 (PDE4) inhibitor → suppression of pro-inflammatory mediator synthesis and promotion of anti-inflammatory mediators
has a better prognosis than RA
Rheumatoid factor is an ___ antibody against ___
IgM ; IgG
[Rheumatoid factor (RF) is a circulating antibody (usually IgM) that reacts with the Fc portion of the patients own IgG.. ]
RF can be detected by either
Rose-Waaler test: sheep red cell agglutination
Latex agglutination test (less specific)
RF is positive in _____ of patients with rheumatoid arthritis, high titre levels are associated with severe progressive disease (but NOT a marker of disease activity
70-80%
Other conditions associated with a positive RF include:
Felty’s syndrome (around 100%)
Sjogren’s syndrome (around 50%)
infective endocarditis (around 50%)
SLE (= 20-30%)
systemic sclerosis (= 30%)
general population (= 5%)
rarely: TB, HBV, EBV, leprosy
Anti-cyclic citrullinated peptide antibody may be detectable up to ___ years before the development of rheumatoid arthritis
10
Role of Anti-cyclic citrullinated peptide antibody in RA dx
It has a key role in the diagnosis of rheumatoid arthritis, allowing early detection of patients suitable for aggressive anti-TNF therapy.
Anti-cyclic citrullinated peptide antibody’s sensitivity and specificity
It has a sensitivity similar to rheumatoid factor (around 70%) with a much higher specificity of 90-95%.
Lab findings in osteoporosis
Normal serum calcium, normal serum phosphate, normal ALP and normal PTH - osteoporosis
Calcium: Normal
Phosphate: Normal
ALP: Normal
PTH: Normal
Osteoporosis
Calcium: Decreased
Phosphate: Decreased
ALP: Increased
PTH: Increased
Osteomalacia
Calcium: Increased
Phosphate: Decreased
ALP: Increased
PTH: Increased
Primary hyperparathyroidism
Calcium: Decreased
Phosphate: Increased
ALP: Increased
PTH: Increased
CKD (secondary hyperparathyroidism)
Calcium: Normal
Phosphate: Normal
ALP: Increased
PTH: Normal
Paget’s disease
________ spread is the most common cause of septic arthritis
Hematogenous
