BMJ. 2008 Apr 26; 336(7650): 902-3
Thomas JM
When melanoma spreads, it invariably does so by the lymphatic system. The first lymph node to be affected is called the sentinel node, and this node can be identified by injecting dye and a radioactive tracer at the primary tumour site. During sentinel lymph node biopsy, the sentinel node is located by a hand held probe and confirmed as the sentinel node using blue dye staining; it is then removed for histology. About 80% of patients have no melanoma in the sentinel node. In the remaining patients, the tumour burden varies from tiny deposits of melanoma in the subcapsular sinus to complete replacement of several sentinel nodes with extracapsular spread. Patients who are sentinel node negative have a better prognosis than those who are sentinel node positive, and the prognosis worsens as the tumour burden increases. But evidence is accumulating that some tiny deposits of melanoma in the sentinel node . . .