What is the likely cause and recommended workup for a 52‑year‑old man with acute swelling, erythema, and warmth of the right hand (base of thumb and index finger) plus pain in the right foot and left wrist, no known injury, and a negative uric acid test?

Acute Inflammatory Polyarthritis – Likely Septic Arthritis or Calcium Pyrophosphate Deposition Disease (CPPD/Pseudogout)

This 52-year-old man with acute swelling, erythema, warmth, and polyarticular involvement (right hand/thumb base, index finger, right foot, left wrist) most likely has septic arthritis or pseudogout (CPPD), and requires immediate plain radiographs of all affected joints followed by arthrocentesis with synovial fluid analysis including cell count, Gram stain, culture, and crystal examination under polarized microscopy 1, 2.

Why This Is Not Gout Despite the Clinical Presentation

The negative uric acid test makes gout less likely but does not exclude it—serum uric acid can be normal or even low during acute gout attacks due to uricosuric effects of inflammation. However, the polyarticular distribution involving hand, wrist, and foot simultaneously in a first presentation makes gout less typical 3.

Most Critical Differential: Septic Arthritis

The constellation of erythema, warmth, swelling at multiple sites with no trauma history raises immediate concern for septic arthritis, which is a surgical emergency:

• Joint swelling with erythema and increased temperature are hallmark features 1
• The "squeeze test" (compression of metacarpophalangeal/metatarsophalangeal joints causing pain) suggests inflammatory arthritis 1
• Septic arthritis can present with polyarticular involvement in 10-20% of cases, particularly in immunocompromised or bacteremic patients

Immediate Workup Algorithm

1. Plain radiographs of right hand, left wrist, and right foot – Initial imaging to exclude fracture, tumor, and assess for joint effusion, soft tissue swelling, or early erosive changes 2

2. Arthrocentesis of the most accessible inflamed joint (likely right hand MCP or left wrist) with:

   • Cell count with differential (septic >50,000 WBC, >90% PMNs)
   • Gram stain and culture (aerobic, anaerobic, fungal if chronic)
   • Crystal analysis under polarized microscopy 1, 2

3. Laboratory tests 1:

   • Complete blood count (leukocytosis suggests infection)
   • ESR/CRP (elevated in both infection and crystal disease)
   • Blood cultures if febrile or systemically ill
   • Antinuclear antibodies, RF (to exclude autoimmune polyarthritis)
   • Urinalysis, transaminases (baseline and exclude systemic disease)

4. If radiographs show soft tissue swelling but aspiration is difficult: Consider ultrasound-guided aspiration or MRI to confirm joint effusion and guide needle placement 2

Second Most Likely: Calcium Pyrophosphate Deposition Disease (Pseudogout)

CPPD classically presents as acute monoarthritis but can be polyarticular in 5-10% of cases:

• Affects wrists, MCPs, and feet—matching this patient's distribution
• Presents with erythema, warmth, swelling mimicking septic arthritis
• Radiographs may show chondrocalcinosis (cartilage calcification)
• Synovial fluid shows positively birefringent rhomboid crystals 4

The negative uric acid actually supports pseudogout over gout in this polyarticular presentation.

Third Consideration: Acute Calcific Periarthritis

Less common but documented in hand/thumb presentations 4:

• Acute calcium hydroxyapatite deposition in periarticular soft tissues
• Radiographs show calcific deposits near joints
• Can mimic infection with severe pain, erythema, warmth
• More commonly monoarticular (thumb MCP in reported cases)

Critical Pitfalls to Avoid

1. Do not delay arthrocentesis based on normal inflammatory markers—septic arthritis can occur with normal WBC/CRP, especially early 2

2. Do not assume polyarticular = rheumatoid arthritis—this acute presentation with erythema/warmth demands infection exclusion first 1

3. Do not rely on negative uric acid to exclude gout—repeat testing after acute phase resolves 3

4. Do not miss imaging-guided aspiration opportunity—if clinical aspiration fails, ultrasound or fluoroscopy guidance significantly improves yield and safety 2

If Septic Arthritis Is Confirmed

• Immediate orthopedic consultation for surgical drainage
• Empiric IV antibiotics (vancomycin + 3rd generation cephalosporin) pending cultures
• Repeat aspiration/washout as needed
• Hand infections require early surgical intervention to prevent permanent functional loss 5

If Crystal Disease Is Confirmed

• NSAIDs (indomethacin 50mg TID) or colchicine (1.2mg then 0.6mg 1 hour later)
• Corticosteroids if NSAIDs contraindicated (prednisone 30-40mg daily)
• Avoid urate-lowering therapy during acute attack if gout confirmed later

The key decision point is arthrocentesis—imaging alone cannot distinguish infected from crystal-induced arthritis 2. Given the polyarticular involvement with inflammatory signs, this patient requires same-day rheumatology or orthopedic evaluation and joint aspiration within 24-48 hours maximum 1.