1) The correct answer is C.
CCP antibody is the most sensitive test for the diagnosis of RA with a sensitivity and specificity of greater than 98%. RF is much less specific and only about 60% sensitive. ANAs can be seen in RA in addition to lupus and other connective tissue disease so is not specific for the diagnosis. HLAB27 can be seen in association with seronegative arthritis. Double stranded DNA is specific for lupus and is not seen in RA.
2) The correct answer is B.
The next best step is to aspirate the joint to rule out infection, particularly since there is one joint out of proportion to the rest. Patients on immunosuppressive therapy sometimes fail to present with the common signs of infection (i.e., fever) and suspicion as such should be high. Aspiration is the only way to diagnose infection in this patient. X-rays and MRI may show an effusion but cannot definitively diagnose infection. Increasing methotrexate or adding steroids until infection is ruled out would be wrong.
3) The correct answer is B.
This patient has scleritis, which can be seen in up to 1% of RA patients. Uveitis is a more common problem in patients with seronegative arthritis such as spondyloarthritis or psoriatic arthritis. A cataract can be seen in patients with RA, particularly as a result of treatment with steroids, however it is not commonly due to the disease itself. Conjunctivitis is an infectious complication of the eye and would be due to immunosuppression, not the underlying disease.
4) The correct answer is A.
These are subcutaneous nodules, more common in more severe RA patients who, like this patient are seropositive for RF and/or CCP antibodies. Nodules may be a sign of more active disease. They can occur in 20-35% of patients. The most common location is on the extensor surfaces of the elbows. Methotrexate is thought to accelerate nodule formation in some patients.
On histology pallisading histiocyles can be seen. Septal panniculitis is seen with E nodousm. Crystals would be indicative of gout.
5) The correct answer is A.
All patients with RA should have an x-ray of the cervical spine prior to undergoing surgery to rule out instability. X-ray should be ordered with flexion and extension views to evaluate for atlanto-axial subluxation. Lumbar spine is not affected in RA so would not be indicated. PFTs would not be required unless there is a history of underlying lung disease. Dopplers wouldn’t be needed since RA patients are not necessarily thought to have increased hypercoaguable risk.