Confocal laser microscopy as novel approach for real-time and in-vivo tissue examination during minimal-invasive surgery in colon cancer.

BACKGROUND: Histological analysis of surgical specimen is the gold standard for cancer classification. In particular, frozen histological diagnosis of vague peritoneal spots or uncertain excision of tumors plays a crucial role in the decision to proceed with or abandon an operation. Confocal laser microscopy (CLM) enables in-vivo and real-time high-resolution tissue analysis. This method has already been used during endoscopic assessments analyzing transformation of esophageal or colon mucosa. We examined whether a CLM device enables to distinguish between non-malignant and malignant tissue in vivo and real time and enables to assign peritoneal carcinomatosis spots to their primary tumor. In addition, we investigated whether the newly developed CLM camera device causes any tissue damage.

METHODS: CC531 colon carcinoma cells were implanted on the serosa side of the colon and intraperitoneally in Wag/Rija rats via laparotomy. After 7 days of tumor growth, confocal laser microscopy in vivo was performed by re-laparotomy. Images of non-malignant and malignant tissue were characterized in terms of specific signal pattern. No fluorescent dye was used. Correlations to findings in conventional histology were systematically recorded and described. Potential tissue damage was examined by conventional histology.

RESULTS: All animals survived the operative procedure and could be evaluated 7 days following surgery. No unexpected death occurred after surgery. Non-malignant colon is defined by small cycles of the microvilli of the colon. There is repetitive deregulated structure in colon carcinoma. Peritoneal carcinomatosis showed the same structural pattern as in primary colon carcinoma. In all examined cases, it was possible to differentiate between peritoneal carcinomatosis spots and non-malignant peritoneum. The CLM device did not cause any tissue damage.

CONCLUSIONS: The CLM camera device reported here is feasible to identify peritoneal carcinomatosis spots, assign these spots to the primary tumor, as well as distinguish between non-malignant and malignant tissue in without using any fluorescent dye.