Differential Diagnosis for Gout

When considering whether a patient's symptoms are due to gout, it's essential to evaluate other potential causes that could mimic or be confused with gout. Here's a structured approach to the differential diagnosis:

• Single Most Likely Diagnosis

  • Pseudogout (Calcium Pyrophosphate Deposition Disease, CPPD): This condition often presents similarly to gout, with sudden, severe joint pain and swelling, most commonly affecting the knee. The key differentiator is the type of crystal found in the joint fluid, with pseudogout involving calcium pyrophosphate dihydrate crystals rather than monosodium urate crystals seen in gout.

• Other Likely Diagnoses

  • Septic Arthritis: An infection within a joint, which can present with acute onset of pain, swelling, and decreased range of motion, similar to gout. Fever and systemic symptoms may also be present.
  • Rheumatoid Arthritis (RA): Although RA typically involves multiple joints and has a more gradual onset, it can occasionally present with a single, acutely inflamed joint, mimicking gout.
  • Osteoarthritis (OA): While OA is generally a chronic condition, acute exacerbations can cause significant pain and swelling in a single joint, potentially mimicking a gout attack.

• Do Not Miss Diagnoses

  • Septic Arthritis: As mentioned, this is a critical diagnosis not to miss due to its potential for rapid joint destruction and systemic infection if not promptly treated with antibiotics.
  • Cellulitis or Soft Tissue Infection: Infections of the skin and soft tissues surrounding a joint can mimic gout in terms of pain and swelling but require antibiotics for treatment.
  • Deep Vein Thrombosis (DVT): Although less common, DVT can cause leg swelling and pain, which might be confused with gout, especially if the gout involves the ankle or lower leg.

• Rare Diagnoses

  • Hemochromatosis: A genetic disorder leading to iron overload, which can cause arthropathy that might be mistaken for gout, although it typically involves multiple joints and has other systemic manifestations.
  • Amyloidosis: A condition characterized by the deposition of abnormal proteins (amyloid) in various tissues, including joints, which can cause symptoms similar to gout, among other presentations.
  • Sarcoid Arthritis: Part of a systemic disease called sarcoidosis, which can cause joint inflammation and mimic gout, though it usually involves multiple joints and is accompanied by other systemic symptoms.

Each of these diagnoses has distinct features and requires careful consideration based on the patient's presentation, history, and diagnostic findings.