Probe-based confocal laser endomicroscopy for optical biopsy of basal cell carcinoma of the auricle.

Objective: The resection of skin tumours of the auricle is confronted with the challenge of keeping the resection defect as small as possible and at the same time achieving a complete resection. Probe-based confocal laser endomicroscopy (CLE) is an optical procedure that enables real-time, non-invasive assessment of the epithelium with up to 1000x magnification in vivo. The aim is to evaluate the feasibility of CLE in basal cell carcinoma (BCC) of the auricle. Methods: Sixty-four video sequences (4,872 images) of CLE images of 8 different patients with BCC on the auricle were analysed. Each video sequence was assigned a histologic diagnosis. The sequences were presented to 4 physicians with experience in CLE in a blinded fashion. Dignity was assessed dichotomously using criteria such as cell size, tissue homogeneity and fibrosis. Results: BCC is characterised by inhomogeneous tissue with enlarged, poorly demarcated cells, partly interrupted by cell-free fibrosis. The assessment of dignity based on the CLE sequences achieved an average sensitivity of 86.7% and a specificity of 94.5%. The interrater reliability (Fleiss Kappa) showed substantial agreement (κ = 0.76). Conclusions: The results demonstrate the initial feasibility of intraoperative CLE for optical biopsy of facial skin tumours. The technique has the potential to serve as a non-invasive diagnostic tool in intraoperative decision making. Further studies are needed to evaluate its use as an adjunct to optimise or reduce the use of invasive frozen section pathology in the treatment of BCC.