Sentinel Lymph Node Mapping in Melanoma: The Issue of False-Negative Findings.
Clinical nuclear medicine (Impact Factor: 3.93). 02/2014; 39(7). DOI: 10.1097/RLU.0000000000000366
Management of cutaneous melanoma has changed after introduction in the clinical routine of sentinel lymph node biopsy (SLNB) for nodal staging. By defining the nodal basin status, SLNB provides a powerful prognostic information. Nevertheless, some debate still surrounds the accuracy of this procedure in terms of false-negative rate. Several large-scale studies have reported a relatively high false-negative rate (5.6%-21%), correctly defined as the proportion of false-negative results with respect to the total number of "actual" positive lymph nodes. In this review, we identified all the technical aspects that the nuclear medicine physician, the surgeon, and the pathologist should take into account to improve accuracy of the procedure and minimize the false-negative rate. In particular, SPECT/CT imaging detects more SLNs than those found by planar lymphoscintigraphy. Furthermore, the nuclear medicine community should reach a consensus on the radioactive counting rate threshold to better guide the surgeon in identifying the lymph nodes with the highest likelihood of housing metastases ("true biologic SLNs"). Analysis of the harvested SLNs by conventional techniques is also a further potential source for error. More accurate SLN analysis (eg, molecular analysis by reverse transcriptase-polymerase chain reaction) and more extensive SLN sampling identify more positive nodes, thus reducing the false-negative rate.The clinical factors identifying patients at higher-risk local recurrence after a negative SLNB include older age at diagnosis, deeper lesions, histological ulceration, and head-neck anatomic location of the primary lesion.The clinical impact of a false-negative SLNB on the prognosis of melanoma patients remains controversial, because the majority of studies have failed to demonstrate overall statistically significant disadvantage in melanoma-specific survival for false-negative SLNB patients compared with true-positive SLNB patients.When new more effective drugs will be available in the adjuvant setting for stage III melanoma patients, the implication of an accurate staging procedure for the sentinel lymph nodes will be crucial for both patients and clinicians. Standardization and accuracy of SLN identification, removal, and analysis are required.
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ABSTRACT: In melanoma, the sentinel lymph node (SLN) status is the most important factor determining overall survival. Lymphoscintigraphy is a current practice evolving since more than 20 years. It represents the standard practice in detecting SLN and includes dynamic imaging and SPECT/CT. This article reviews the different technical aspects of lymphoscintigraphy with their advantages. It also reviews the main other ways of SLN imaging in melanoma, including more specific techniques, some of them representing a field of research. A PUBMED (MeSH) search was performed with the following keywords: sentinel lymph node melanoma imaging and reviewed relevant articles. We excluded case reports, publications with an Impact Factor lower than 2 and older than 10 years. The use of dynamic and delayed images combined with preoperative SPECT/CT and blue dye during surgery remains the method of choice in sentinel lymph node melanoma detection. SPECT/CT provides several advantages, in particular a higher rate of node detection, better nodes localization and reduction of operative time, with significantly reducing costs. To provide longer retention in lymphatic nodes, some targeted agents are developed but their clinical use is limited. Lymphatic staging with imaging contrast agents could directly assess nodal status without surgery and could be a promising method for the future.06/2015; 3(3). DOI:10.1007/s40336-015-0122-2
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