Rheumatology Week 7 Summary

Question 31

What are the 5 typical patterns of joint involvement in psoriatic arthritis?

1. Asymmetric oligoarthritis
   (“Oligo” means that fewer than five joints are involved)
2. Symmetric polyarthritis
   (Sometimes indistinguishable from rheumatoid arthritis)
3. Symmetric arthritis with distal interphalangeal joint predominance
4. Arthritis mutilans
   (A particularly deforming subset of the disease)
5. Spondyloarthritis

Question 32

List 6 features that should raise suspicion of giant cell arteritis (GCA or temporal arteritis) in a patient over age 50. What features on history and exam carry the highest likelihood ratio for the presence of giant cell arteritis?

The risk of giant cell arteritis rises with increasing age and the condition does not occur in patients under age 50. Features that should raise suspicion of GCA in this population include:

1. New headache
2. Temporal artery abnormality (tenderness or decreased pulsation)
3. Scalp tenderness
4. Jaw claudication
5. Tongue claudication
6. Arm claudication
7. Sudden visual disturbances
8. ESR ≥50mm/h by Westergren method

Features that confer a high likelihood of temporal arteritis include the following:

1. Jaw Claudication (LR +4.2)
2. Diplopia (LR +3.1)
3. Beaded Temporal Artery (LR +4.6)
4. Prominent or enlarged artery (LR +4.3)
5. Tender temporal artery (LR +2.6)
6. Absent temporal artery pulse (LR +2.7)

Smetana GW, Shmerling RH. Does this patient have Temporal Arteritis? JAMA 2002 January 2;287:92-101

Question 33

What does “ANCA” stand for? What rheumatologic condition is most strongly associated with the presence of C-ANCA? List three disease associations with P-ANCA.

“ANCA” stands for anti-nuclear cytoplasmic antibodies.

On immunofluorescence, a C-ANCA is characterized by diffuse cytoplasmic staining. This usually corresponds with antibodies to the antigen PR3 (proteinase-3).

P-ANCA refers to a perinuclear immunofluorescence staining pattern and usually corresponds with antibodies to the antigen MPO (myeloperoxidase).

80-90% of patients with Wegener’s granulomatosis are C-ANCA positive. In some patients, C-ANCA titres reflect disease activity. Microscopic polyangiitis, Churg-Strauss vasculitis, renal-limited vasculitis and Goodpasture’s (anti-GBM) disease are all associated with the presence of P-ANCA. Note that P-ANCA positivity is also associated with a number of non-rheumatologic conditions, including drug-related vasculitis, connective tissue diseases, inflammatory bowel disease, and cystic fibrosis.

Question 34

What is the relationship between polyarteritis nodosa (PAN) and hepatitis B?

PAN is a medium vessel vasculitis that can affect the skin, the GI tract, the kidneys and the nerves. While PAN is a relatively rare disease, up to half of all PAN cases are secondary to hepatitis B. Classic PAN usually manifests within the first 6 months of hepatitis B infection.

Treatment includes plasmapheresis to remove circulating immune complexes, antiviral agents, and prednisone.

Question 35

Corticosteroids are commonly used for joint injections. When obtaining informed consent for such a procedure, what are the potential side effects that must be discussed with a patient? What are the absolute and relative contraindications to such an injection?

1. Infection
   (This is quite rare, with an estimated risk of 1/10,000)
2. Tendon rupture
3. Post-injection flare
   (an acute arthritis that is likely due to crystallization of the steroid within the joint)
4. Skin atrophy/depigmentation at site of injection
   (a particular risk in dark-skinned individuals)
5. Facial flushing which may last one or two days
6. Temporary worsening of glycemic control in diabetics (lasting days)

Contraindications to corticosteroid injection include:

1. Infected tissue overlying the injection site
2. Suspected infection in the joint to be injected
3. Bacteremia
4. Prosthetic joints – you should involve orthopedics rather than placing a needle in a prosthetic joint for any reason, as the risk of introducing an infection is much higher than in a native joint.
5. Patients who are anticoagulated can be aspirated or injected with caution if they are within a therapeutic INR or PTT range.