Q56) A 42 year old presents with a pain & swelling in the left knee. The symptoms started 3days ago and have been progressively worsening. Upon further questioning, the patient tells you that he has experienced intermittent pain and swelling in the toes, wrists and ankles for more than 10 years. On examination the left knee is swollen and warm to touch. There is also soft tissue swelling of the wrists, ankles and right foot. He has a 10 year history of intermittent pain & swelling in the toes, wrists & ankles. On examination the right knee is warm to touch with an effusion, & there is soft tissue swelling of the wrists, right ankle & right foot. X-ray of the wrist is shown below. Laboratory studies reveal increased ESR at 90mm/hr WBC are elevated at 12k.
The most likely diagnosis :
A. Early erosive osteoarthritis
B. Reactive Arthritis
C. Psoriatic Arthritis
D. Pseudo-Gout
E. Rheumatoid Arthritis
Q57) The most important next step in management :
A) Obtain Rheumatoid Factor level
B) Obtain Anti citrullin peptide level
C) Start prednisone
D) Start ibuprofen and Methotrexate
E) Arthrocentesis of the Right knee
Archer USMLE Step 3 Blog 
a
e
D,E
answer is e and d
Q56) Ans. E
The patient’s clinical presentation is consistent with acute flare of Rheumatoid arthritis. The x-ray reveals extra-articular erosion of ulnar styloid process. The involvement of proximal joints with accompanying soft tissue swelling, symmetrical involvement, history of chronic arthritis and extra-articular erosions on the x-ray are consistent with the diagnosis of Rheumatoid Arthritis. American Rheumatism Association (ARA) has developed 6 criteria for the diagnosis of RA. 4 out of this 6 criteria are necessary to diagnose RA. These include morning stiffness more than one hour, arthritis of 3 or more joint areas, arthritis of hand joints (wrist, MCP or PIP joint), Symmetric arthritis, Rheumatoid nodules, Serum rheumatoid factor
and Radiographic changes typical of rheumatoid arthritis on posteroanterior hand or wrist radiographs, which must include erosions within the involved joint or adjacent to the involved joints. This patient already has 4 out of six criteria for RA.
Ans. A is incorrect. Early onset erosive OA is an important differential diagnosis of RA but the patient’s radiographic features, symmetricity, proximal joint involvement are more typical of RA.
Ans. B is incorrect. Reiter’s syndrome is characterized by asymmetric pattern of joint involvement, symptoms or signs of enthesopathy ( inflammation at the site of tendon insertion) and radiographic evidence of sacro-ileitis. This patient has symmetrical arthritis which readily eliminates the possibility of Reiter’s syndrome.
Ans. C is incorrect. Psoriatic arthritis can be either symmetric or asymmetric oligoarthritis or polyarthritis. Symmetric polyarthritis presentation of psoriatic arthritis is sometimes difficult to differentiate from RA. In addition to inflammatory arthritis, the diagnosis of psoriatic arthritis requires three of the following features : dactylitis, psoriatic skin lesions, typical nail lesions ( pitting or onycholysis), negative rheumatoid factor and juxta-articular new bone formation seen on the x-rays. In the presence of typical psoriatic skin lesions, only one additional feature of the above is sufficient for diagnosis. The patient in the question does not meet this criteria.
Ans. D is incorrect. Pseud-gout is usually acute mono-arthritis or oligoarthritis. It is very uncommon for pseudo-gout to present with polyarthritis. Pseudo-gout is also characterized by chondro-calcinosis which is deposition of calcium pyrophosphate crystals in the articular cartilage. Chondro-calcinosis can be visualized on the X-rays. The x-ray presented in the above case does not reveal chondrocalcinosis.
Q57) Ans. E
The patient has clinical criteria sufficient to diagnose Rheumatoid Arthritis. The current presentation of acute left knee swelling and pain could be related to a flare of RA. However, septic arthritis should be included in the differential diagnosis of any acute large joint swelling. Septic arthritis is also more common in RA patients when compared to general population. Hence, a joint aspiration must be performed to exclude septic arthritis before attributing such an acute large joint presentation to a RA flare.
Ans. A is incorrect. The patient satisfies clinical criteria for RA diagnosis. A rheumatoid factor is adjunctive and will not help in confirming the etiology of her left knee swelling.
Ans. B is incorrect. The patient satisfies clinical criteria for RA diagnosis. A anti-citrullinated peptide is adjunctive and will not help in confirming the etiology of her left knee swelling. Anti-CCP positivity also carries an unfavorable prognosis in RA.
Ans. C is incorrect. It is inappropriate to start steroid with out excluding septic arthritis.
Ans. D is incorrect. It is inappropriate to start treatment of RA with out excluding septic arthritis in this patient’s left knee. Treatment for RA can be initiated after arthrocentesis. Ibuprofen can be used to relieve her symptoms and a DMARD such as Methotrexate should be started due to presence of erosions on the radiographs. In the absence of erosions, a milder DMARD such as hydroxychloroquine should be started.
E and E
WOW!!!!!
Get Rheumatology specialist to answer this question
consult rheumatologist, but make d/d
Fischer says CCP, not joint aspirate, going with Archer and crossing my fingers.