Detecting the sentinel lymph node in patients with differentiated thyroid carcinoma

The aim of this study was to evaluate sentinel lymph node mapping in patients with differentiated thyroid carcinoma. Nine patients with suspected thyroid carcinoma who were scheduled to undergo thyroidectomy underwent scintigraphic localization of sentinel lymph nodes (SLNs). On the day of surgery we injected 37 MBq technetium-99m nanocolloid intratumourally. Dynamic data up to 10 min followed by planar anterior and lateral oblique images up to 1 h after tracer administration were recorded. At surgery the primary tumour was excised first, then the SLNs were removed using a gamma probe. Four patients had papillary carcinoma, two follicular carcinoma, one an oncocytic tumour and two benign tumours. An SLN was identified in all four patients with papillary carcinoma. In the two patients with follicular carcinoma, SLN detection failed. Five patients had one radioactive node, one had three and one had four. In one patient, no SLN was visible with scintigraphic imaging but at surgery three SLNs could be clearly identified using the gamma probe after removal of the primary tumour. There were no false-negative findings. This initial study indicates that in patients with papillary thyroid carcinoma detection of the SLN is possible, whereas the technique failed in two patients with follicular carcinoma. A study on a larger patient sample is now warranted.