Fluorescence-based confocal microscopy in the diagnosis of head and neck carcinomas

It is common practice to use frozen section diagnostics for the resection of squamous cell carcinomas in the head and neck region. Fluorescence-based confocal microscopy (FCM) is a new method increasingly used as a diagnostic tool in various fields (dermatology, urology, hepatology). In this method, after a short (2-minute) preparation, two lasers (different wavelengths) are used, allowing cellular and extracellular structures to be visualized simultaneously and converted into a virtual HE section. The aim of the study was to gain initial experience in the application of this procedure for head and neck surgery. Fresh unfixed tissue was first analysed using FCM (VivaScope 2500M-G4, MAVIG GmbH, VivaScope Systems, Munich, Germany) and subsequently by means of conventional frozen section diagnostics and routine paraffin embedding (gold standard). Positive and negative predictive value and image quality (semi-quantitative, grade 1-5) were compared. Five fresh tissue samples (1x larynx, 3x oropharynx, 1x oral cavity) were analysed using the FCM technique. The positive and negative predictive value was 100% (1x PLECA, 1x adenoca., 3 x without malignancy). On average, the image quality for FCM was 2.5 (rapid step 1.2, paraffin 1.1) according to the investigators' assessment. Initial results from this small cohort on the use of the FCM technique in the head and neck region show promising results and will now be repeated with a larger sample size. The image quality of the FCM technique is presumably subject to a learning curve and is likely to improve significantly in the future. Provided the FCM technique is successfully tested, this form of image acquisition could in future take place close to the patient in the operating theatre and thus shorten the time needed for evaluation.