Microscopic Findings of Fluorescence of Liver Cancers

Abstract

Reports detailing microscopic observations of indocyanine green (ICG) fluorescence imaging (IFI) in hepatocellular carcinoma (HCC) and metastatic liver cancer are rare. We were able to perform microscopic IFI results in postoperative paraffin-embedded tissue samples from liver tumors. Methods: Between April 2010 and March 2014, 19 patients with HCC or liver metastases of colorectal tumors underwent liver resection. ICG solution was injected into the peripheral vein from 14 to 2 days prior to operation. After operation, we microscopically performed tissue section IFI using a fluorescence microscope with a near-infrared cube. Results: We observed that IFI characteristics depended on tumor type microscopically. In normal liver tissue, fluorescence consistent with a capillary bile cavity was observed. HCC generally had heterogeneous IFI. Well- or moderately differentiated HCC showed cytoplasmic fluorescence as observed by ICG fluorescence microscopy. Furthermore, poorly and unknown differentiated HCC except one case showed nuclear fluorescence in cancer cells and cytoplasmic fluorescence in the surrounding noncancer cells. In metastatic carcinoma, we observed that non-tumor cells in the marginal region and tumor cells in the central region did not fluoresce. Conclusions: We suggest that the variations in ICG fluorescence imaging patterns may reflect different tumor characteristics. ICG fluorescence in paraffin-embedded tissue samples is preserved in the long term.