The Usefulness of Staining Lymph Nodes During Operations for Cancer Thyroid in Detecting the Nodes That Have Cancer

Overview

Detection of lymph nodes starting to be involved by cancer spreading from the thyroid gland during operation is useful. It saves the patient from having a second operation to remove these nodes later on when they become obvious. The problem is that there are many lymph nodes around the gland. The theory is that only one node will get the first spill of the tumour cells. In this study the investigators are trying to use an inert colored material to inject into the tumour. This should run in the same path as the tumour cells and should therefore stain the one lymph node that will be affected first should the tumour spread. The stained lymph node is excised and examined instantaneously for tumour affection. If it is found to be affected by the tumour, then the operation is extended to include removal of all its fellow lymph nodes. If it is found to be free from the tumour, then this patient does not have tumour spread.

The study includes 45 consecutive patients diagnosed as differentiated thyroid cancer by clinical examination and/or fine needle aspiration cytology (FNAC). Exclusion criteria are: previous neck surgery, pregnancy and known hypersensitivity to the dye used. An informed consent was obtained from all the patients. Peroperative workup includes history taking, clinical examination, relevant laboratory investigations including thyroid hormone assay, ultrasonography of the neck with special emphasis on the thyroid focal lesion and cervical lymph nodes. FNAC was attempted in all patients. All patients were then subjected to operation: A systematized surgical approach was adopted for the purpose of the study: this started by collar incision, development of sub-platysmal skin flaps and separation of strap muscles in the midline. This was followed by exposure of the thyroid gland; identification of the thyroid tumour; injection of the dye into the tumour; waiting for the dye to reach the lymph nodes; identifying the stained node; labeling it as the sentinel node (SLN); performing total thyroidectomy and bilateral central neck dissection. The resected specimen was fixed by formaldehyde, stained with hematoxylin and eosin and examined with light microscopy. If the SLN was found to be free of malignant deposits, it was further examined by immunohistochemical staining. Statistical analysis: Descriptive statistics were used to analyze demographic data. Sensitivity, specificity and predictive value of the SLN were calculated. The histopathological report of the excised specimen was considered the criterion standard.