Feasibility of sentinel lymph node biopsy and lymphatic mapping in nodularthyroid neoplasms

Although the prognostic significance of occult lymph node metastases in thy roid cancer remains controversial, identifying these patients may help dire ct therapy. The purpose of this study was to determine the feasibility and safety of sentinel lymph node biopsy (SLNBx) in thyroid nodular disease. Pa tients undergoing thyroid resection, with no evidence of clinical lymphaden opathy, were enrolled. The nodule was injected with isosulfan blue vital dy e, flue-stained lymphatic channels were traced within the central compartme nt to the SLN, which was excised. A total of 40 patients underwent SLNBx; l ymphatics were seen in 31 patients, and SLNs were found in 26. In 11 patien ts the lymphatic vessels were traced through the central compartment into t he lateral or mediastinal compartments, although a central SLN was retrieve d in only 6. Of the 18 patients with benign neoplasms, 14 had benign SLNs, and no SLN was found in 4. A thyroid lymphoma patient had a true positive S LN. In the 12 patients with papillary thyroid cancer (PTC), 6 had true posi tive SLNs, and 2 had a true negative SLN. In one patient with metastatic PT C, the parathyroid stained blue. Another patient with PTC had lateral lymph atic channels, but no SLN was found. There were two false negatives, proven by a node dissection in one and lateral uptake on I-131 scanning in the ot her. There were no postoperative complications. SLNBx for thyroid disease i s feasible and safe. Potential staining of the parathyroids makes their ide ntification before injection mandatory. The variable lymphatic drainage pat terns and the two false-negative nodes indicate that further investigation is required before the procedure can be recommended for patients with thyro id disease.