Definition of Sentinel lymph node

Sentinel lymph node: The first lymph node ("gland") to receive lymphatic drainage from a tumor.

Which lymph node is the sentinel node in a given case is determined by injecting around the tumor a tracer substance that will travel through the lymphatic system to the first draining (sentinel) node and identify it. The tracer substance may be blue dye that can be visually tracked or a radioactive colloid hat can be radiologically followed.

Biopsy of the sentinel lymph node can reveal whether there are lymphatic metastases. If the sentinel node contains tumor cells, removal of more nodes in the area may be warranted. If the sentinel node is normal, this obviates the need for extensive dissection of the regional lymph-node basin.

Sentinel-lymph-node biopsy has, for example, become a standard technique for determining the nodal stage of disease in patients with malignant melanoma.