Ultrasound-guided Core Needle Biopsy (US-CNB) of Superficial Lymph Nodes: an Alternative to Fine-Needle Aspiration Cytology (FNAC) for the Diagnosis of Lymph Node Metastasis in Melanoma.

e20026 Background: Fine-needle aspiration cytology (FNAC) is used in most of experienced centers to confirm melanoma metastatic spread to the lymph node. In our University Hospital, UltraSound-guided Core Needle Biopsy (US-CNB) is used for all superficial lymph node biopsies. Our objective was to investigate the diagnostic value of US-CNB in the diagnosis of lymph node metastasis in melanoma and compare it to FNAC accuracy in the literature. Methods: All patients with invasive melanoma followed in Saint-Louis Hospital between 2006 and 2010, who underwent a US-CNB for a suspicion of melanoma lymph node metastasis, were retrospectively screened. Histological results of US-CNB samples were diagnosed as melanoma, other malignancy, suspicious, inadequate or benign. The diagnostic accuracy was assessed by comparison with 2 reference standards: histopathological examination of the radical lymph node dissection, or when it was not available, clinical and radiological follow-up. The amount of tissue yielded was evaluated and mutational analysis results were reviewed. Results: The data from 72 patients were analyzed. 44 melanoma, 22 benign, 3 other malignancies, 3 inadequate samples and no inconclusive specimens were diagnosed. 71 US-CNB results were confirmed (98.6%). US-CNB achieved high sensitivity, specificity and PPV (respectively 97.9%, 100 %, and 100 %). No adverse events were reported after the procedure. USGCNB provided a mean tissue volume of 16.7 mm3 per lymphadenopathy allowing to perform complete analysis for BRAF, NRAS and c-KIT mutational status in 10 patients. Conclusions: US-CNB possess similar diagnostic value to FNAC for which sensitivity and specificity values in metastatic melanoma have ranged between 86.5 and 100 %. Recent studies about FNAC demonstrated inconclusive rates ranging from 3.3 to 18.8% whereas our series demonstrated none. US-CNB constitutes a reliable diagnostic method in melanoma lymph node metastasis to avoid surgical procedures in patients who will not benefit from it, and provides large samples of tissue suitable for comprehensive genomic analyses.