Rate of false-negative findings in sentinel lymph node biopsy in patients with head and neck malignant melanoma.

e17566 Background: Sentinel Lymph Node Biopsy (SLNB) is the standard procedure for malignant melanoma with a thicknes above 1mm. However, the benefits of this procedure have recently been questioned because of a high number of false negative findings. The aim of our study was to investigate the number of early recurrence in patients with negative SLNB. Methods: All patients with malignant melanoma of the head and neck region who underwent SLNB between 2010 and 2016 in our department were included and data reviewed retrospectively. Recurrence in the same cervical lymph node region of the previously extirpated sentinel lymph node (SLN) within one year was defined as primary false-negative. Results: Allover 101 patients were investigated (mean age 62.48 years (±17.66; 73.3% ♂, 26.7% ♀). Most frequent location of the primary melanoma were the cheeks and ears (each 18.8%), followed by the hair bearing region (13.9%). Superficial Spreading Melanoma and Nodular Melanoma were the most frequently seen subtypes (each 23.8%), followed by Lentigo maligna Melanoma (19.8%). Median thickness of all patients was 2.5mm (min: 0.15 – max: 10.0 mm). In average 3 SLN were removed during operation (min: 1 – max 16). In 79.2% of the cases the SLN was negative. 13% showed one metastasis, 5.2% showed two and 1.6% three metastases. Positive findings in the SLN were significantly correlated with T-classification. Ulceration and tumor thickness showed significant tendencies in Χ2-Test and Mann-Whitney-Test. Out of the patients with negative SLN 13.1% had at least one metastasis in a cervical lymph node of the same region within one year. Mean duration until recurrence was 6.5 months. 75.0% of the metastases in our study were diagnosed within this period. 62.5% of the patients with secondary positive SLN had a tumor of intermediate thickness (between 1mm and 4mm). Conclusions: With 13.1 % secondary positive SLN this study shows that SLNB has a high rate of false-negative findings. However, SLNB has lower complication rates compared to traditional lymph node extirpation. This study shows that patients with negative SLN especially with intermediate tumor thickness should be controlled by ultrasound or computer tomography in short intervals.