Since then, more experience has been gained with the procedure and the reporting of SLNs. When SLN mapping procedure began to be the standard of care a few years ago, the SLNs were histologically examined on multiple levels and cytokeratin stains on at least two levels. Dabbs MD, in Diagnostic Immunohistochemistry, 2019 Sentinel Lymph Node Immunohistochemistryįor the surgical pathologist, the appropriate triage and examination of the SLN is of utmost importance, but even here some controversy exists. If axillary metastasis is not confirmed by FNAB, patients can proceed to sentinel node surgery for staging.ĭavid J. If axillary metastasis is confirmed, patients can proceed directly to standard axillary node dissection or be considered for preoperative chemotherapy. Patients who present with clinically palpable lymph nodes should be evaluated with axillary ultrasonography and fine-needle aspiration biopsy (FNAB) of the nodes. 18 Surgeons should be trained in SLND before using this procedure as a staging tool. The false-negative rate for sentinel node surgery ranges from 0% to 11%, as reported in the NSABP B-32 trial. Surgeons experienced in SLND can identify a sentinel node in more than 95% of patients. Published studies have demonstrated an average of two or three sentinel nodes per patient. If the level of radioactivity remains high, additional sentinel nodes may remain in the nodal basin, and additional dissection should be completed to remove all sentinel nodes. The sentinel node may be identified and removed, after which the nodal basin is checked again to confirm that the level of radioactivity has decreased. If a blue-stained lymphatic channel or a specific area of radioactivity (“hot spot”) cannot be identified, the primary tumor can be resected to remove the site of injection, decreasing the background shine-through radioactivity. Dissection is performed to avoid prematurely disrupting the afferent lymphatics. After the incision is made, an area of increased radioactivity is localized with the handheld gamma probe, and the surgeon visualizes blue lymphatic channels leading to the sentinel node. A handheld gamma probe is used to localize transcutaneously the area of increased radioactivity this helps to guide placement of the incision for the sentinel node procedure. In the operating suite, 3 to 5 mL of blue dye can be injected peritumorally, and the injection site is massaged to facilitate passage of the dye through the lymphatics. Alternatively, for surgeons not using preoperative lymphoscintigraphy, 0.5 to 1.0 mCi of 99mTc-labeled sulfur colloid can be injected in the operating suite and avoids the preoperative pain and vasovagal events. A dose of 2.5 mCi of 99mTc-labeled sulfur colloid can be injected on the day before surgery for preoperative lymphoscintigraphy this allows for adequate activity to remain in the sentinel nodes for the intraoperative lymphatic mapping procedure the following day without the need for reinjection. If a subareolar or subdermal injection technique is used, drainage is seen almost exclusively in the axillary nodal basins. Using a peritumoral injection technique, approximately 70% of patients have drainage to the axilla, 20% have drainage to the axilla and the internal mammary nodal basin, 2% to 3% have drainage to the internal mammary nodal basin alone, and 8% do not show any drainage to the regional nodal basins. Preoperative lympho‑scintigraphy can provide information on the specific nodal basins draining the primary tumor. Studies indicate that using the combination technique may result in the lowest possible false-negative rate. Lymphatic mapping can be performed with a combination of 99m Tc-labeled sulfur colloid and a vital blue dye, isosulfan blue (Lymphazurin), fluorescence, magnetic particles, or with a single agent for localization of the sentinel node(s). Townsend JR., MD, in Sabiston Textbook of Surgery, 2022 Lymphatic Mapping Technique and Selection of Patients for Sentinel Lymph Node Dissection
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