What are the potential causes and evaluation approaches for a patient presenting with unilateral hand swelling?

Unilateral Hand Swelling: Causes and Evaluation

Immediate Life-Threatening Causes

Unilateral hand swelling always indicates an obstructive process requiring urgent evaluation, unlike bilateral swelling which suggests systemic causes. 1, 2

Upper Extremity Deep Vein Thrombosis (UEDVT)

• UEDVT accounts for up to 10% of all DVTs and can cause pulmonary embolism, presenting with ipsilateral upper-extremity edema, pain, and prominent superficial veins serving as collaterals around the obstruction 1
• Risk factors include indwelling venous devices (central lines, pacemakers), dialysis access (AV fistula or graft), cancer, recent surgery, hypercoagulability, and trauma 1, 2
• Bulging veins represent collateral circulation bypassing the obstructed deep venous system—a hallmark of venous thrombosis or central venous stenosis 1
• Duplex ultrasound of the upper extremity must be performed urgently with sensitivity and specificity above 80% for UEDVT 1, 2

Soft Tissue Infection

• Radiographs may show soft tissue gas, foreign bodies, or periosteal reaction suggesting infection 3, 2
• CT with IV contrast can differentiate cellulitis, myositis, tenosynovitis, and abscess formation 4
• Image-guided aspiration for culture should be obtained, and broad-spectrum antibiotics started after cultures 3, 2

Vascular Causes

Arterial Insufficiency

• Unilateral cold painful hand is an appropriate indication for upper extremity arterial testing 4
• Finger discoloration or ulcer warrants arterial evaluation 4
• Suspected positional arterial obstruction (thoracic outlet syndrome) requires assessment 4

Central Venous Stenosis

• Ipsilateral extremity swelling without other cause suggests central venous stenosis, particularly in patients with dialysis access 1
• Swelling persisting beyond 2 weeks after dialysis access placement requires venography or CT venography to evaluate central veins 1
• If ultrasound cannot visualize thoracic vessels adequately, proceed to CT venography or MR venography 1

Inflammatory/Rheumatologic Causes

Early Inflammatory Arthritis

• Joint swelling warrants rheumatology referral within 6 weeks, as early arthritis can occur with negative serologies 3
• Normal ANA does not exclude inflammatory arthritis; RF, anti-CCP antibodies, ESR, and CRP should be obtained 3
• Ultrasound with power Doppler or MRI can detect synovitis when clinical examination is equivocal 4, 3
• US can identify synovitis, joint effusion, tenosynovitis, tendinopathy, and tendon injury 4

Pachydermodactyly

• Rare benign condition presenting as painless, spindle-shaped soft-tissue swelling of proximal interphalangeal joints, usually in adolescent males 5
• Associated with frequent finger cracking, normal inflammatory markers, and normal radiographs showing only soft tissue swelling 5
• Skin biopsy reveals hyperkeratosis with thick collagenous fibers in dermis 5

Drug-Related Causes

Puffy Hand Syndrome

• Occurs in patients with history of intravenous drug use (can be unilateral if injection limited to one extremity) 6, 7
• Can initially appear several years after drug injection has been discontinued 6
• Presents with erythema and pitting edema; often mistaken for cellulitis or inflammatory arthritis 6, 7
• Hepatitis C infection is a common comorbidity 6, 7
• Cultures are negative for pathogens; serologic evaluation negative for rheumatologic diseases 6
• Treatment includes compression bandaging and lymphedema therapy 6, 7

Lymphatic Causes

Lymphedema

• Congenital lymphedema (lymphedema praecox) can cause unilateral limb swelling 8
• May be complicated by cellulitis requiring antibiotic treatment before lymphedema therapy 8

Diagnostic Algorithm

Step 1: Initial Imaging

Plain radiographs in two planes are mandatory as the first investigation for any suspected musculoskeletal pathology with swelling, looking for soft tissue gas, foreign bodies, periosteal reaction, bone destruction, or calcifications 3, 2

Step 2: Urgent Vascular Assessment

• Perform duplex ultrasound immediately to exclude UEDVT using grayscale imaging to visualize thrombus and assess vein compressibility 1, 2
• Doppler assessment evaluates blood flow patterns, cardiac pulsatility, and respiratory variation 1
• Test for central vein collapse with rapid inspiration ("sniffing maneuver") 1

Step 3: Advanced Imaging Based on Initial Findings

• MRI without IV contrast is indicated when malignancy cannot be excluded on radiographs and provides optimal local staging of extremity tumors 3, 2
• MRI changed clinical management in 69.5% of cases in patients referred to hand surgeons 4
• CT with IV contrast if infection suspected to assess soft tissue extent and guide aspiration or surgical debridement 4

Step 4: Tissue Diagnosis When Indicated

• Image-guided aspiration for culture if infection suspected 3, 2
• Skin biopsy if puffy hand syndrome or pachydermodactyly suspected 6, 5
• All biopsies for suspected tumor must be performed by the surgeon who will perform definitive resection 2

Management Priorities

If UEDVT Confirmed

• Initiate therapeutic anticoagulation immediately following standard DVT treatment protocols with minimum duration of 3 months for axillary or more proximal vein involvement 1, 2
• Investigate lower extremities if no local cause identified 1, 2

If Inflammatory Arthritis Suspected

• Initiate DMARD therapy (methotrexate as anchor drug) early, even if classification criteria not fully met, if patient at risk for persistent or erosive disease 3

If Infection Identified

• Obtain cultures via image-guided aspiration and start broad-spectrum antibiotics after cultures obtained 3, 2
• Surgical consultation for debridement if abscess or necrotizing infection identified 3

Follow-Up Protocol

• Reassess within 48-72 hours to evaluate response to initial management and ensure no progression 3, 1, 2
• Schedule formal re-evaluation at 6 weeks if edema persists to detect delayed complications or maturation of underlying pathology 3, 1, 2

Critical Pitfalls to Avoid

• Do not dismiss unilateral swelling as benign—it demands urgent evaluation for venous obstruction, unlike bilateral swelling 1, 2
• Do not attribute unilateral swelling with bulging veins to neurogenic thoracic outlet syndrome without excluding venous thrombosis 1
• Recognize that catheter-associated UEDVT may be asymptomatic initially, manifesting only as catheter dysfunction 1, 2
• Do not mistake puffy hand syndrome or pachydermodactyly for inflammatory arthritis and expose patients to unnecessary immunosuppressive therapy 5, 7
• In dialysis patients, persistent swelling beyond 2-6 weeks post-access creation warrants investigation for central venous stenosis, not just local access complications 1