The sentinel lymph node was defined as the first lymph node to receive drainage from a primary cancer. The aims of this study were to investigate the efficacy of radiocolloid lymphoscintigraphy and of the hand-held gamma probe procedure for sentinel lymph node biopsy in papillary thyroid carcinoma and to evaluate these results in clinical staging. A total of 99 consecutive papillary thyroid carcinoma patients entered the study. Patients underwent radiocolloid lymphoscintigraphy before surgery. Intra-operative sentinel lymph node localization was performed using a hand-held gamma probe. Patients were observed at follow-up at 2 and 6 months and, thereafter, yearly. Sequential lymphoscintigraphy was able to identify at least one sentinel lymph node in 98/99 cases (99%), using intra-operative hand-held gamma probe, the surgeon was able to detect at least one sentinel lymph node in all cases. Sentinel lymph node metastases were diagnosed in 49%. Overall, 79 patients underwent ablative 131I therapy. The median value of thyroglobulin in N0 vs. N1 patients was 1 ng/ml vs. 1.9 ng/ml (p = 0.03) and 0.2 ng/ml vs. 1 ng/ml (p = 0.001) before and after 131I therapy, respectively. The pre-operative lymphoscintigraphy and the intra-operative gamma probe offer significant advantages over the vital dye technique, described in our previous experience. The rate of nodal involvement (49%) is very high considering that no patients had clinically palpable nodes or suspected at echography. 131I whole body scan and thyroglobulin measurements confirmed sentinel lymph node in papillary thyroid carcinoma as a reliable procedure. In patients classified N0, by sentinel lymph node biopsy, ablative 131I therapy could be avoided
