What is the cause of left hand swelling and pain in a patient with no apparent wound, where gout has been ruled out?

Differential Diagnosis of Left Hand Swelling and Pain Without Wound (Gout Ruled Out)

Most Likely Diagnostic Considerations

With gout definitively excluded, the primary differential diagnoses for acute hand swelling and pain without trauma include septic arthritis, calcium pyrophosphate deposition disease (CPPD/pseudogout), inflammatory arthritis (rheumatoid arthritis, psoriatic arthritis), and less commonly, dialysis access-related steal syndrome in patients with arteriovenous fistulas.

Immediate Priority: Rule Out Septic Arthritis

• Joint aspiration with synovial fluid analysis is mandatory when septic arthritis cannot be clinically excluded, as this represents a medical emergency that can rapidly become lethal if untreated 1, 2
• Gram stain and culture must be performed on any joint aspirate, as crystal arthropathies and septic arthritis can coexist 1
• Clinical features suggesting septic arthritis include fever, systemic signs of infection, severe pain, warmth, and inability to bear weight or use the affected hand 1
• Do not delay arthrocentesis if infection is suspected—this takes diagnostic priority over all other considerations 1

Calcium Pyrophosphate Deposition Disease (CPPD/Pseudogout)

• CPPD is the second most common crystal arthropathy and frequently affects the wrist and metacarpophalangeal joints of the hand 1
• Definitive diagnosis requires identification of calcium pyrophosphate crystals in synovial fluid—these appear as rhomboid-shaped, weakly positively birefringent crystals under polarized microscopy 1
• Conventional radiography and ultrasound are the recommended initial imaging modalities for CPPD diagnosis 1
• Look for chondrocalcinosis on plain radiographs, particularly in the triangular fibrocartilage of the wrist 1
• Risk factors include advanced age, osteoarthritis, hyperparathyroidism, hemochromatosis, and hypomagnesemia 1

Inflammatory Arthritis

• Rheumatoid arthritis characteristically affects the metacarpophalangeal and proximal interphalangeal joints in a symmetric pattern, though early disease may be asymmetric 3
• Morning stiffness lasting more than 30-60 minutes suggests inflammatory arthritis rather than mechanical or crystal-induced disease 3
• Psoriatic arthritis can present with dactylitis ("sausage digit") and may affect the distal interphalangeal joints, distinguishing it from rheumatoid arthritis 3
• Consider checking rheumatoid factor, anti-CCP antibodies, inflammatory markers (ESR, CRP), and screening for psoriatic skin or nail changes 3

Dialysis Access-Related Complications (If Applicable)

• In patients with arteriovenous fistulas for hemodialysis, hand swelling and pain may indicate steal syndrome or venous hypertension—this requires emergent vascular surgery referral 1
• Steal syndrome presents with coldness, pain (especially during dialysis), and potentially tissue necrosis if severe 1
• Venous hypertension from outflow stenosis causes hand edema, pain, and tissue acidosis 1
• Delay in recognition can lead to catastrophic gangrene and hand amputation—immediate vascular surgery consultation is mandatory if this is suspected 1
• Digital blood pressure measurement and duplex Doppler ultrasound should be performed urgently 1

Diagnostic Algorithm

1. First: Assess for septic arthritis risk—if fever, systemic symptoms, or high clinical suspicion exists, perform immediate arthrocentesis with Gram stain and culture 1, 2

2. Second: Obtain plain radiographs of the hand—look for chondrocalcinosis (CPPD), erosive changes (inflammatory arthritis), or soft tissue calcifications 1

3. Third: If joint aspiration is feasible and diagnosis remains uncertain, perform arthrocentesis—analyze for calcium pyrophosphate crystals (rhomboid, weakly positive birefringence) and inflammatory cell count 1

4. Fourth: If inflammatory arthritis is suspected, check serologic markers—rheumatoid factor, anti-CCP antibodies, ESR, CRP 3

5. Fifth: In dialysis patients with arteriovenous access, urgently evaluate for steal syndrome or venous hypertension—perform digital blood pressure measurement and duplex Doppler ultrasound, with immediate vascular surgery referral if positive 1

Common Pitfalls to Avoid

• Never assume a non-infectious cause without definitively ruling out septic arthritis—the consequences of missing this diagnosis are catastrophic 1, 2
• Do not rely on normal inflammatory markers to exclude infection—septic arthritis can occur with normal ESR/CRP in immunocompromised patients 1
• In dialysis patients, do not attribute hand symptoms to "fluid overload" without evaluating for access-related steal syndrome—this delay can result in limb loss 1
• CPPD can coexist with gout, so even if gout was "ruled out," consider that both crystal types may be present 1
• Ultrasound can detect synovitis and guide arthrocentesis in difficult-to-aspirate small joints of the hand 1