Sentinel lymph node biopsy

Goal:

• To stage the axilla

Principles:

• Dual localisation
• Aim for 1-3 nodes

Pitfalls:

• Inadequate nodal harvest
• Taking more nodes than is necessary

SLNB localisation techniques

• ^99mTc-labeled sulphur colloid combined with intra-op gamma probe
  • Considered safe in pregnancy
  • <24 hours pre-op
• Blue dye - 3-5mL
  • Can use either patent blue/isosulfan blue (50mg in 2mL, diluted up to 5mL; 0.16-1.1% anaphylaxis) or methylene blue (5mg in 5mL sterile water - can also be given as a last resort in septic shock - can cause skin necrosis with intra-dermal injection, lower rate of anaphylaxis)
  • Can be injected subareolar, subdermal or peri-tumoural (not intradermally as it will cause a tattoo, and not into the tumour itself)
    • If injected peri-tumoural, 70% of patients have axillary drainage, 20% have drainage to both axilla and internal mammary basin, 2-3% to internal mammary basin alone, and 8% do not show drainage to regional nodal basin
    • If injected subareolar, virtually all drainage is to the axilla
  • Not safe in pregnancy due to risk of anaphylaxis (1/1000)
  • If significant hypotension occurs, usually abandon the procedure, support the patient and plan subsequent surgery without blue dye

Technique

• TT, GA, prep and drape taking care of hookwire, IV Abx, TEDs, incision marked on breast, blue dye
• Supine, ipsilateral arm out, myself standing medial on ipsilateral side
• SLNB
  • Small axillary incision at inferior border of hair-bearing skin, somewhat localised using Geiger counter
  • Deepen incision into axillary fat towards node, using diathermy - assistant with Adson's, then cat's paws, then Langenbeck's; instruct assistant to hold steady as they won't be able to see
  • Look for blue lymphatic channels and dissect/ligate carefully; use Geiger intermittently
  • Expect to see blue node with higher signal
  • Babcock grasper to remove from wound, dissect down to pedicle, remove
  • Ideally 2-3 nodes (avoid additional adjuvant therapy/clearance)
  • Take formal count using Geiger counter, send to pathology
    • Take background count in axilla, if >10% of the node you removed, may need to chase more nodes
  • Palpate for other nodes in axilla
  • If unable to find nodes, check axillary tail of breast tissue, level III, and tissue posterior axilla
  • Haemostasis and ray-tec, leave wound open for closing later

Difficulties:

• No nodes found
  • Inject 10mL saline peri-areolar and further massage
  • Next step would be level 1 dissection/sampling - consider whether this is justified based on patient factors and disease factors - if younger, more likely to do it
• >3 nodes found
  • Controversial whether to take them all or leave them
  • Easiest thing to do is leave them after 3 convincing nodes are found