Question

multiple choice question
a 65 - year - old female presents with acute onset severe pain and swelling in her right knee joint. she denies any recent trauma but mentions a history of osteoarthritis in her family. on examination, the affected joint is warm, erythematous, and tender to touch. laboratory tests reveal calcium pyrophosphate crystals in the synovial fluid. what is the most likely diagnosis?
please select your answer...
a osteoarthritis
b pseudogout
c rheumatoid arthritis
d gout

Explanation:

• Osteoarthritis (A): Usually presents with gradual onset, joint pain related to activity, and no crystals in synovial fluid.
• Pseudogout (B): Characterized by acute - onset joint pain, swelling, warmth, and erythema. The presence of calcium pyrophosphate crystals in synovial fluid is diagnostic.
• Rheumatoid arthritis (C): Typically involves multiple joints, symmetrically, with morning stiffness lasting more than 1 hour, and synovial fluid shows inflammatory cells but no calcium pyrophosphate crystals.
• Gout (D): Caused by monosodium urate crystals. Synovial fluid analysis would show needle - shaped, negatively birefringent monosodium urate crystals, not calcium pyrophosphate crystals.

Answer:

B. Pseudogout