[Sentinel lymph node procedure in thyroid carcinoma patients. Our experience]

How far to extend surgical treatment of papillary thyroid carcinoma (PTC) is still an open question. A contribution may derive from intraoperative lymphatic mapping because, in other malignancies, the procedure has become an important aid in defining lymph node status. The aim of this study was to evaluate the feasibility of sentinel lymph node (SLN) mapping performed by intratumoural injection of vital blue dye to guide nodal dissection in PTC.

One hundred and ten patients were selected for the study, all of them had a preoperative diagnosis of PTC, but no clinical or ultrasonographic evidence of nodal involvement. Following cervicotomy and exposition of the thyroid gland, vital blue dye was injected into the malignant thyroid nodule. Subsequently, total thyroidectomy and lymph node dissection were carried out, and the thyroid, the SLN(s) and the other lymph nodes were sent for frozen section and definitive histologic evaluation.

Intraoperative lymphatic mapping located sentinel lymph nodes in 74 cases (67.3%); the SLN was detected in the laterocervical compartment (LC) in 4 cases (5.4%), with the ''sick'' of the CC. In 23 of these 74 patients (31.1%) the SLN(s) were positive for micro-metastases and in 15 cases (65.2%) both the SLN and other resected nodes were found positive. In the 51 cases in whom the SLN was disease-free, the other nodes were also negative. Of the 36 cases in whom the SLN was not detected, in 4 cases (11.1%) a parathyroid gland was stained and in 1 case (2.8%) fibroadipous tissue was stained. To date, of the 23 patients with positive-SLN 22 patients are living without disease (95.6%), 1 patient is living with disease (4.4%); all patients with negative SLN are living without disease; of the 36 patients without staining of the SLN, 35 are living without disease (97.2%) and 1 patient is deceased for reasons different from PTC (2.8%).

On the basis of this study, we underline some disadvantages in using Blue Patent V dye in SLN biopsy procedure as: a) the risk of disruption and interruption of the lymphatics from the tumour; b) blue dye uptake by a parathyroid gland which is successively mistakenly removed; c) the ''seak'' of the CC that doesn't permit to disclose SLN that lies outside the central compartment.