The sentinel lymph node in papillary cancer of the thyroid including histological subtype.

The aim of this work was to reveal through sentinel node study the intraoperative presence of preoperatively undetected pathological lymph nodes. At the Surgical Science Department of La Sapienza University of Rome The Authors studied from January 2003 to June 2004 18 patients with papillary carcinoma of the thyroid, who presented no clinical evidence of lymph node metastasis; they performed a total thyroidectomy in all cases, removing and histologically examining all lymph nodes of the upper anterior mediastinum. Where negative they were then subjected to immunohistochemical analysis with Pan Cytokeratin. The method was positive in 10 patients: 2 pure papillary carcinomas, 1 papillary carcinoma with poorly differentiated areas, 1 tall cell papillary carcinoma, 5 sclerosing carcinoma and 1 follicular variant papillary carcinoma; and negative in 8:5 pure papillary carcinomas, 2 sclerosing carcinoma and 1 case of follicular variant papillary carcinoma. Lymph node micrometastasis was found in 2 cases through study with Pan Cytokeratin on final histological examination. Analysis of the Authors' preliminary data shows that sentinel lymph node detection has 83.3% sensitivity and 100% specificity for Upper Anterior Mediastinum lymph nodes. The Authors can propose two main applications: select for dissection only patients with a positive sentinel node and reduce the number of cases to be subjected to postoperative treatment with iodine ablation, in patients with "low risk" thyroid tumours and negative sentinel nodes.