What is the workup for an injured, swollen, bruised thumb with a lump or nodule on the wrist?

Workup for Injured Swollen Bruised Thumb and Wrist Lump/Nodule

The initial workup for an injured, swollen, bruised thumb with a wrist lump/nodule should begin with standard 3-view radiographs of both the thumb and wrist, followed by advanced imaging based on radiographic findings. 1

Initial Imaging

Radiography (First-Line)

• Thumb imaging: Minimum of 2 views (posteroanterior and lateral), with slight increase in diagnostic yield by adding an oblique projection 1
• Wrist imaging: 3-view examination including:
  • Posteroanterior (PA)
  • Lateral
  • 45° semipronated oblique view 1
  • Consider additional carpal tunnel view or "scaphoid view" if there's clinical suspicion of scaphoid injury 2

Secondary Imaging (If Radiographs Are Negative or Equivocal)

For Suspected Fracture

If radiographs are negative but clinical suspicion for fracture remains high:

1. MRI without IV contrast:

   • Highest sensitivity for occult fractures and bone marrow changes
   • Can detect concomitant ligamentous injuries
   • Preferred for detecting stress fractures 1, 2

2. CT without IV contrast (alternative):

   • Excellent for bone detail and fracture characterization
   • Faster acquisition time than MRI
   • Particularly useful for complex fractures or surgical planning
   • Better for hook of hamate fractures 1

3. Repeat radiographs in 10-14 days (less optimal):

   • May show healing response
   • Risk of delayed diagnosis and treatment 1

For Suspected Wrist Lump/Nodule

If the lump appears to be soft tissue in nature:

1. Ultrasound:

   • Excellent for evaluating soft tissue masses, especially superficial ones
   • Can distinguish solid from cystic lesions
   • Allows dynamic assessment of tendons
   • High accuracy (97.4%) for soft tissue hand injuries 3
   • Can guide removal of foreign bodies if present 1

2. MRI without IV contrast (alternative):

   • Superior for characterizing soft tissue masses
   • Can diagnose specific benign conditions (lipomas, hemangiomas, nerve sheath tumors)
   • Excellent for detecting occult ganglion cysts 1
   • Consider MRI with contrast to distinguish ganglia from synovitis 1

For Suspected Foreign Body

If there's history of penetrating injury:

1. Ultrasound:

   • High sensitivity for detecting foreign bodies in superficial soft tissues
   • Allows assessment of surrounding tendons and vascular structures 1

2. CT without IV contrast (alternative):

   • High sensitivity for radiopaque foreign bodies
   • Recommended if foreign body is suspected in deep tissues or bone 1

Special Considerations

Thumb-Specific Assessment

• Evaluate for fractures of metacarpal, proximal or distal phalanx
• Assess for tendon injuries (extensor pollicis longus/brevis, flexor pollicis longus)
• Check for ligamentous injuries, especially ulnar collateral ligament (gamekeeper's thumb)

Wrist Lump Assessment

• If radiographs show carpal malalignment without fracture, consider:
  • MRI without IV contrast for soft tissue evaluation
  • CT without IV contrast for detailed bony assessment 1

Common Pitfalls to Avoid

1. Inadequate radiographic views: Using only 2 views for wrist imaging significantly reduces diagnostic yield 1

2. Missing scaphoid fractures: These can be radiographically occult initially and lead to avascular necrosis if missed 2

3. Delayed treatment: Can compromise long-term function and lead to complications including malunion, non-union, and osteoarthritic changes 2

4. Overlooking soft tissue injuries: Focusing only on bony structures may miss important ligamentous or tendinous injuries that require treatment 1, 2

5. Underestimating long-term impact: Hand/wrist impairment can persist for years after trauma if not properly managed 2

By following this systematic imaging approach, clinicians can accurately diagnose the cause of thumb injury and wrist lump/nodule, allowing for appropriate treatment to minimize morbidity and optimize functional outcomes.