Visualization of Gastric Adenocarcinoma Lymph Node Metastases by Microscopy with Ultraviolet Surface Excitation

The detection of lymph node metastases is crucial in oncopathology, as it makes it possible to determine the TNM stage, to design a treatment plan, and predict the survival for cancer patients. The current gold standard for this process is hematoxylin and eosin staining. However, new alternative methods leveraging the unique optical properties of tissue structures are being developed for rapid intraoperative or postoperative application. The aim of the study is to evaluate the effectiveness of identifying lymph node metastases using microscopy with ultraviolet surface excitation (MUSE).

17 lymph nodes from the Sechenov University archive (Russia) collected intraoperatively from 6 patients with gastric cancer have been investigated.In this study, we utilized a MUSE optical system consisting of three UV light-emitting diodes (265 nm) and the Axio Scope A1 microscope (Carl Zeiss, Germany) with various objectives. We introduced a novel combination of fluorescent dyes - Nile red and Hoechst - that had not been previously used with MUSE.

The combination of fluorescent dyes yielded high-contrast images with blue-stained nuclei and orange-to-red stained cytoplasm, effectively visualizing gastric adenocarcinoma cells characterized by abundant cytoplasmic components and large polymorphic nuclei. The presence of irregularly shaped cavities, formed by adenocarcinoma metastases, was also detectable by MUSE.

Biophotonics provides alternative methods for tissue imaging. However, traditional methods are still unsurpassed in the accuracy of detecting cancer metastases and other pathologies. Further refinement of imaging protocols and expanded research into other cancer types are needed to make methods like MUSE applicable for intraoperative diagnosis.