Utility of Multistep Protocols in the Analysis of Sentinel Lymph Nodes in Cutaneous Melanoma: An Assessment of 194 Cases.

Abstract

Currently, no universal protocol exists for the assessment of sentinel lymph nodes (SLNs) in cutaneous melanoma. Many institutions use a multistep approach with multiple hematoxylin-eosin (H&E) and immunohistochemical stains. However, this can be a costly and time- and resource-consuming task. To assess the utility for multistep protocols in the analysis of melanoma SLNs by specifically evaluating the Calgary Laboratory Services (CLS) protocol (which consists of 3 H&E slides and 1 S100 protein, 1 HMB-45, and 1 Melan-A slide per melanoma SLN block) and to develop a more streamlined protocol. Histologic slides from SLN resections from 194 patients with diagnosed cutaneous melanoma were submitted to the CLS dermatopathology group. Tissue blocks were processed according to the CLS SLN protocol. The slides were re-reviewed to determine whether or not metastatic melanoma was identified microscopically at each step of the protocol. Using SPSS software, a decision tree was then created to determine which step most accurately reflected the true diagnosis. We found with Melan-A immunostain that 337 of 337 negative SLNs (100%) were correctly diagnosed as negative and 55 of 56 positive nodes (98.2%) were correctly diagnosed as positive. With the addition of an H&E level, 393 of 393 SLNs (100%) were accurately diagnosed. We recommend routine melanoma SLN evaluation protocols be limited to 2 slides: 1 H&E stain and 1 Melan-A stain. This protocol is both time- and cost-efficient and yields high diagnostic accuracy.