Optical coherence tomography and confocal laser scanning microscopy as non-invasive tools in the diagnosis of sinonasal inverted papilloma: a pilot study.

Optical coherence tomography (OCT) and confocal laser scanning microscopy (CLSM) are light-based imaging techniques that allow for a visualization of microscopic tissue properties in vivo. Our study was to examine whether they allow for differentiation of inverted papilloma (IP) from nasal polyps (NP). Five cases of IP and NP, respectively, were investigated intraoperatively with OCT and CLSM. Biopsies were taken of the investigated area and were analyzed ex vivo with OCT and CLSM and then underwent HE-staining for standard light microscopy. On OCT images, IP showed the characteristic inverted character of the epithelium, that was thicker with a high degree of variability of thickness compared to the thin and homogenous epithelium of NP. In addition, the characteristic stromal edema of NP could be visualized. On CLSM images, the typical epithelial invaginations of IP appeared as crypts, while in NP the highly organized cylindric epithelium could be visualized. In vivo, OCT acquired images of sufficient quality to visualize these characteristics, while CLSM did not. Our study demonstrates that OCT and CLSM can distinguish IP from NP. Further technical development is required to apply the techniques clinically to guide intranasal biopsies or even to make them dispensable.