Sentinel lymph node biopsy
SLNB is not simply “find and remove a node”. Reliability depends on the whole chain: correct indication, lymphatic mapping, removal of the true sentinel node and dedicated pathology processing.
Accuracy is built across several stages
SLNB is a method of pathological staging for clinically node-negative regional basins. Its purpose is to identify the first lymph nodes on the drainage pathway from the primary melanoma and assess them correctly.
The current Ukrainian protocol provides for technetium-based radionuclide mapping or indocyanine green (ICG) for sentinel-node detection. Mapping defines the true lymphatic drainage pathway and sentinel nodes.
After surgery an equally important stage begins: correct gross processing and multilevel microscopic assessment.
The current Ukrainian protocol requires serial levels, H&E and immunohistochemistry with multiple melanocytic markers. A single arbitrary section is not an adequate assessment of the sentinel node.
SLNB is not required for every patient with melanoma
The decision depends primarily on Breslow thickness, ulceration, clinical nodal status and other risk factors. A separate page covers indications in detail.
SLNB is not a single manoeuvre
From indication to the final report, every stage influences the value of the result.
01IndicationBreslow thickness, ulceration, clinical N0 status and correct timing.
02MappingDefinition of true lymphatic drainage and regional basins.
03IdentificationIdentification of all sentinel nodes according to the map and navigation signal.
04RemovalSeparate designation and submission of each sentinel node.
05Gross processingSystematic tissue sampling rather than a single arbitrary fragment.
06H&E + IHCSerial levels, morphology and immunohistochemistry.
07ReportNumber of nodes, tumour burden, location and other key parameters.
How the sentinel lymph node is identified correctly
The sentinel node is defined by the lymphatic drainage pathway from the primary melanoma. Mapping establishes which nodal basin or basins receive drainage and which nodes are truly sentinel.
Supports preoperative lymphatic mapping and intraoperative sentinel-node identification using a detector.
A fluorescence-guided navigation method also provided for sentinel-node detection in the current Ukrainian protocol.
The operative stage - video and clinical clip
A short real-world example of intraoperative navigation and targeted identification of a sentinel lymph node.
The operation is over. SLNB is not over
This is where the second half of the procedure is often underestimated: correct pathology assessment of the removed sentinel node.
A small tumour deposit may be missed on a single arbitrary level. IHC increases detection sensitivity but does not replace morphology: a positively stained cell alone does not prove metastasis.
IHC is important - but it cannot be interpreted without morphology
A nodal nevus and melanoma metastasis may express some of the same melanocytic markers.
More than “positive” or “negative”
The report should make clear what was examined and what tumour burden was identified.
And how many contain metastasis.
An important descriptor of tumour burden.
Subcapsular, parenchymal or another pattern.
Reported when present; international protocols also describe additional parameters.
A positive sentinel node is important information, not a verdict
A positive SLN means melanoma cells have been confidently identified in a regional sentinel node. It changes pathological staging, risk assessment and the next management step, but it does not automatically mean that distant metastases are present.
SLN involvement confirms regional nodal metastasis. Exact stage also depends on the primary melanoma, number of involved nodes and other pathological features.
The report should go beyond “SLN positive”: largest deposit size, microanatomic location, number of positive nodes and extranodal extension all matter.
The result may alter systemic staging, surveillance and discussion of adjuvant systemic therapy at the multidisciplinary team meeting.
A positive SLN starts the next part of the pathway
Management should not be based on the single word “positive”, but on the full disease picture.
What do trials tell us about the possible value of early nodal detection?
MSLT-I showed an important signal, not a universal answer. Among patients with intermediate-thickness melanoma (1.2-3.5 mm) and nodal metastases, 10-year melanoma-specific survival was 62.1% with biopsy-based early detection versus 41.5% with observation until clinically evident nodal relapse; HR for melanoma death 0.56 and HR for distant metastasis 0.62. However, there was no significant melanoma-specific survival difference in the overall MSLT-I population, and the node-positive subgroup analysis has methodological limitations. These numbers therefore do not prove that SLNB itself improves survival for every patient.
MSLT-II changed practice after a positive SLN: routine completion lymph-node dissection did not improve melanoma-specific survival compared with observation, although regional nodal control was better. Importantly, MSLT-II tested management after an already positive SLN; it did not compare SLNB with no SLNB. A positive SLN therefore matters today primarily for staging, prognosis, surveillance and systemic-treatment decisions.
Six useful questions after a positive SLN
Open a question to see a concise practical answer, the evidence behind it and direct links to the primary sources.
What is my exact pathological stage after this result?
In brief: if systemic staging shows no distant metastases, a positive SLN confirms regional nodal involvement and places the melanoma in pathological stage III. The exact IIIA-IIID substage cannot be determined from the word “positive” alone.
Final staging integrates the primary tumour T category, ulceration, number of involved nodes, how nodal disease was detected and systemic staging. SLN deposit size is prognostically important, but it does not replace full TNM staging.
What is the largest metastatic deposit and is extranodal extension present?
This matters clinically. The pathology report should ideally state the largest deposit in millimetres, number of deposits, microanatomic location, number of positive SLNs and whether extranodal extension is present.
Tumour burden is especially relevant in AJCC8 stage IIIA. KEYNOTE-054 and COMBI-AD enrolled IIIA patients only when the SLN metastasis was >1 mm. ESMO 2025 states that for AJCC8 IIIA with <1 mm SLN tumour burden, adjuvant systemic therapy is generally not standard because prospective benefit has not been validated.
Do I need additional CT / MRI / PET-CT or other staging tests?
Systemic staging should be completed after a positive SLN before the next treatment decision. The aim is to confirm whether disease remains regional or whether distant metastases are present.
ESMO recommends high-quality staging imaging in this setting, using CT or PET/CT for systemic assessment together with brain MRI. The exact work-up depends on what has already been done, disease stage, symptoms and the local care pathway.
Should adjuvant immunotherapy or targeted therapy be discussed?
A positive SLN does not automatically mean systemic therapy for everyone. The decision depends on substage, SLN tumour burden, recurrence risk, comorbidity and tumour molecular profile.
For completely resected stage III melanoma, adjuvant anti-PD-1 therapy has a strong evidence base; for BRAF V600E-mutated melanoma, dabrafenib + trametinib is an evidence-based alternative. For AJCC8 stage IIIA with <1 mm SLN tumour burden, ESMO 2025 generally does not recommend adjuvant systemic therapy as standard. For BRAF V600K, ESMO 2025 does not recommend adjuvant dabrafenib + trametinib based on the final COMBI-AD data.
Do I need additional nodal surgery, or is active surveillance appropriate?
Routine completion lymph-node dissection after a positive SLN is no longer standard. In MSLT-II, completion dissection did not improve melanoma-specific survival compared with active surveillance. Regional control was better after dissection - about 92% versus 77% at 3 years - but lymphedema was substantially more frequent: 24.1% versus 6.3%.
DeCOG-SLT likewise showed no advantage in DMFS, RFS or OS. ESMO 2025 explicitly advises against routine CLND after a positive SLNB.
What is the schedule for clinical review and nodal ultrasound?
MSLT-II provides a practical evidence-based model for active nodal surveillance: clinical examination and ultrasound of the relevant nodal basin every 4 months for the first 2 years, then every 6 months during years 3-5; clinical follow-up continued annually thereafter.
This does not mean every patient should mechanically follow the same calendar. ESMO emphasises that there is no single optimal follow-up schedule: the frequency of review, nodal ultrasound and systemic imaging should be tailored to stage, individual risk, adjuvant treatment and access to high-quality ultrasound.
Red flags do not automatically mean “error”
They mean the available document does not allow the completeness of the process to be assessed and additional information or expert review may be appropriate.
There is no documentation of the technique used, draining nodal basins or the number of sentinel nodes identified.
Without the number of examined sentinel nodes, method, levels or IHC, it is difficult to understand how completely the node was assessed.
Morphology, cell location, a marker panel and, when needed, the primary melanoma should be correlated.
For clinicians and pathologists
A separate professional section covers international protocols, mapping techniques, grossing, serial sectioning, IHC, nodal nevus versus metastasis and causes of false-negative and false-positive interpretations.
Core sources
The Ukrainian protocol provides the national practice framework; international recommendations add technical and pathology detail.