The role of sentinel node biopsy in the management of MelTUMPs (melanocytomas)
Sentinel lymph node biopsy (SLNB) provides the most accurate staging for invasive melanoma and is therefore required for staging tumours greater than 1.0mm Breslow thickness according to the 8th edition of the AJCC system. However, the role of SLNB in MelTUMPs has not been established and therefore a systematic review of the current evidence was undertaken.
The systematic review found a total of 19 eligible studies: no randomised controlled trials, two prospective studies, 15 retrospective cohort studies, one case-control study and a systematic review.
The duration of follow-up was quite short in most of the studies, with an overall mean of 40 months. Because there were no randomised controlled trials, the reliability of the results is uncertain.
A total of 316 patients underwent sentinel node biopsy, with 112 found to have positive sentinel nodes, a rate of 35%. However, despite the high rate of sentinel node positivity in the MelTUMP patients, there was only one MelTUMP-related death reported amongst all of the 112 patients with a positive node, a mortality rate of less than 1%. The patient who died had a diagnosis of a borderline deep penetrating naevus. For comparison, the rate of sentinel node positivity in the MSLT-1 study was 16% and the corresponding 5-year mortality rate for this group was 47%.
The quality of the MelTUMP studies included did not permit a formal meta-analysis of the results, however, it is clear that the prognostic significance of a positive sentinel node biopsy is qualitatively very different between melanomas and MelTUMPs. Consequently, there is little prognostic utility in performing sentinel lymph node biopsy for MelTUMPs.
Evidence summary and recommendations
|Sentinel lymph node biopsy has a highly variable positivity rate in MelTUMPs, but a high mean rate of around 35%. However, positivity does not appear to correlate with melanoma recurrence or death.||III-1, III-2, III-3||, , , , , , , , , , , , , , , , , , |
|Most lesions classified as MelTUMPs behave as benign lesions, particularly in young patients.||III-2|||
|Age should not be used to determine the prognosis of a patient with a MelTUMP.||C|
It is advisable to have pathologists with expertise in the examination of melanocytic lesions review the tumour slides to confirm or reject a suspected diagnosis of MelTUMP.
Issues requiring more clinical research study
Longer term follow-up of patients with MelTUMPs, particularly those who have had a positive sentinel node biopsy, would be useful to fully determine its clinical significance. Additional studies with molecular characterisation of lesions are necessary to determine whether there are distinct disease entities within the category of MelTUMP and how to distinguish them from bona fide naevi and melanomas.
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