Today’s case was a 70yo man from the Philippines with active colorectal cancer on chemotherapy as well as a history of gout and CKD4 who presented with a week of subjective fevers and knee pain and swelling refractory to his normal outpatient gout management.
- Gout and septic arthritis can present very similarly. In an immunocompromised patient, always consider septic arthritis even if the pain is not severe.
- Triggers for gout flares include dietary noncompliance, alcohol, med noncompliance, diuretics, and chemotherapy
- Tuberculosis can cause monoarticular septic arthritis, but the most common form of skeletal TB is Pott’s disease (spinal TB). Extraaxial skeletal TB affects large joints usually (hip or knee) and can be a “cold” joint without erythema or warmth.
- Interpretation of synovial fluid studies:
- WBC <2000 noninflammatory (trauma, OA, etc)
- WBC >2000 inflammatory vs. crystalline vs. septic
- The higher your WBC count, the more concerned you should be for septic arthritis
- Gram stain and culture all synovial fluid to evaluate for septic arthritis, which can occur simultaneously with a gout/pseudogout flare or inflammatory arthropathy.
- Gout: Negatively birefringent crystals (yellow, needle-shaped)
- CPPD: Positive biregringent crystals (blue, rhomboid)
For a comprehensive review of gout presentation, diagnosis, and management, see the following blog post: https://scvmcmed.com/?s=gout. Or search gout on the right side of this page.