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Hot or not? The 10% rule in sentinel lymph node biopsy for malignant melanoma revisited
A D Murphy1, A Britten2, B Powell1
1St. George's Melanoma Unit, Dept. of Plastic Surgery, St. George's Hospital, Blackshaw Road, London SW17 0QT, UK.
Background:
The surgeon needs a practical rule to follow when deciding whether to excise a lymph node during sentinel node biopsy (SLNB). The "10% rule" dictates that all nodes with a radiation count of greater than 10% of the hottest node and all blue nodes should be removed, and this study observes the effects of following this rule in SLNB in melanoma.
Methods:
We reviewed the records of 665 patients with primary melanoma who underwent sentinel lymph node over a 5-year period (2007-2011).
Results:
2064 nodes were identified in 898 nodal basins in 665 patients. 141 (21%) patients had at least one positive sentinel node. 105 positive nodal basins were identified in which more than one sentinel node was removed. In 18 of these, a less radioactive node was positive for tumour when the most radioactive node was negative. Of 175 positive nodes 157 (90%) contained blue dye staining. For cases in which the positive sentinel node was not the hottest node, the positive node had apparent blue dye staining in all 18 cases (100%), and was the second hottest node in the basin.
Conclusion:
In this series removing just the hottest node and all blue nodes would not have missed a single positive basin and would have resulted in a 38% reduction in the number of nodes removed compared to those taken following the 10% rule, without changing the staging in any patient.
