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
Source: PubMed


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: Background Metastasis of sentinel lymph node (SLN) is generally evaluated on histopathological examination and controversy still exists over the usefulness of PCR assay of SLN.Objective To investigate the prognostic value of triple-marker PCR assay of SLN.MethodsA total of 165 patients with primary cutaneous melanoma who underwent SLN biopsy were included. Clinical and histopathological data were retrieved from each patient's file and triple-marker PCR assay (tyrosinase, GP-100 and MART-1) was performed on the SLN as well as routine histopathological evaluation. PCR positivity was defined as the expression of all three PCR markers. To evaluate melanoma-specific survival (MSS) and disease-free survival (DFS), we used the Kaplan–Meier method and the log-rank test. Multivariate analyses using the Cox proportional hazards regression model were also performed.ResultsSentinel lymph nodes were identified in all 165 patients: 61 patients (37.0%) were male and 104 (63.0%) were female, with a mean age of 60.2 years. Of the 165 melanomas, 81 (49.1%) were acral lentiginous melanomas. Compared with the patients with PCR positivity (1–2 markers) or PCR negativity, patients with PCR positivity (3 markers) had significantly poor MSS (5-year survival rate, 58.7% vs. 84.4%; P < 0.0001) and DFS (5-year survival rate, 25.0% vs. 83.9%; P < 0.0001), with median follow-up of 42 months for MSS and 38 months for DFS. These survival rates of patients with PCR positivity (3 markers) were lower than those of patients with histopathologically positive SLN. In multivariate analysis, PCR positivity (3 markers) was an independent prognostic factor for both MSS (hazard ratio [HR], 2.81; 95% confidence interval [CI], 1.07–7.33; P = 0.035) and DFS (HR, 2.48; 95% CI, 1.08–5.69; P = 0.032).Conclusions The expression of three PCR markers was a significant prognostic factor for both MSS and DFS and might be closely correlated to a dismal prognosis.
    No preview · Article · Sep 2014 · Journal of the European Academy of Dermatology and Venereology
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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.
    No preview · Article · Jun 2015
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    ABSTRACT: Patients with invasive malignant melanoma are commonly referred for sentinel lymph node (SLN) detection. A recently proposed 3D tomographic imaging modality is freehand SPECT (declipseSPECT). This "bedside system" was originally developed to enable minimal-invasive image-guided surgery. The aim of this retrospective analysis was to assess the clinical use of this freehand detector device for image-guided lymphatic mapping in melanoma patients. Thirty-nine patients (12 female and 27 male subjects) were included (age, 30-79 years). All of them had at least one location of melanoma with tumoral stage pT1b or greater in 37 and pTx in 2 patients in different sites of the body (abdomen in 4, back in 14, head and neck in 5, lower extremity in 6, and upper extremity in 10 patients). Lymphoscintigraphy was performed with 65 to 127 MBq Tc-nanocolloid. A 2-day protocol was applied with SPECT-CT acquisition (Brightview XCT, Philips) at day 1 and surgery using radio-guided freehand SPECT at day 2. SPECT-CT data were integrated into the 3D navigation system to enable fast and direct localization of the SLN by displaying the depth of the node from the skin surface and lateral margins in relation to the gamma probe. Comparable preoperative imaging and intraoperative localization was observed in 18 patients. In 14 cases, more lymph nodes were resected than detected by SPECT-CT including 1 patient without evidence of an SLN because this node was located close to the primary right ear tumor. In 10 of these patients, intraoperative freehand SPECT revealed additional sites of lymph nodes. In 7 cases, more findings were detected by SPECT-CT than surgically removed. The procedure was safe and easy to perform, and the time of surgical intervention using freehand SPECT was in the range of 36 to 133 minutes (mean time, 66.56 minutes). Freehand SPECT detected more SLN compared with SPECT-CT, and the tracking system provided precise anatomical localization of the radioactive-labeled SLNs.
    No preview · Article · Jul 2015 · Clinical nuclear medicine
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