Lymphoscintigraphy in Patients with Melanoma

Abstract

Sentinel lymph node biopsy was first described in melanoma patients. The technique requires accurate location of the sentinel nodes using lymphatic mapping, and the surgical removal of only those nodes receiving direct lymphatic drainage from the primary tumor site. When careful histologic examination is added, unprecedented accuracy in staging the regional lymph nodes is achieved. The important role of lymphoscintigraphy in this process is to reveal the precise lymphatic road map to the draining sentinel nodes (SN) in each patient, using radiolabeled tracers. The actual lymphatic collecting vessels can be followed on dynamic imaging until a sentinel node is reached. Only such sentinel nodes should be removed, and second-tier nodes that receive trace upstream should remain in place to avoid unnecessary surgical morbidity. The use of lymphoscintigraphy in large numbers of melanoma patients has redefined the patterns of lymphatic drainage of the human skin with new drainage pathways described to unexpected node fields. New hybrid SPECT/CT imaging provides the precise anatomical location of sentinel nodes, greatly aiding their surgical removal especially in the head and neck region and pelvis.