Abstract

Cutaneous melanoma is one of the leading causes of death among all primary cutaneous neoplasms. The prognosis of primary cutaneous melanoma has been shown to be associated with the presence of metastasis in sentinel lymph node (SLN). Conventional tumor burden evaluation in the SLN is measured via the largest tumor deposit in two-dimensions. However, when the tumor deposit is multifocal and irregular in shape, this method of measurement may be inaccurate. With the implementation of digital pathology, it has become possible to measure the whole area involved by metastatic melanoma. Here we annotated the tumor deposit area and entire surface area of sentinel lymph nodes in 80 patients whose SLN was examined from 2018 to 2019. The tumor deposit area and percentage (divided by the SLN surface area) were correlated with the patients’ survival status and compared to the conventional two-dimensional method. Our results have shown the median tumor area is 0.62 mm² (range: 3.87 um² to 315.58 mm²); the median surface SLN area is 46.95 mm² (range: 0.020 to 338.27 mm²); the median tumor percentage is 0.21% (range: 0.00008 to 93.29%). Using the two-dimensional method, the median length of the tumor deposit is 0.85 mm (range: 0.19 to 108 mm). The 4-year survival rate among these 80 patients is 82.5%. Cox proportional hazard ratios are 1.01 for tumor area (p=0.016), 5.93 for tumor percentage (p=0.012) and 1.12 for tumor length (p=0.0047). While all these tumor burden metrics are predictive for patient’s survival, the prognostic value appears to be similar.