Fluorescence confocal microscopy on liver specimens for full digitization of transplant pathology

Fluorescence confocal microscopy (FCM) is a rapidly evolving tool that provides real-time virtual hematoxylin-eosin (HE) images of native tissue. Data about the potential of FCM as an alternative to frozen sections for the evaluation of donor liver specimens are lacking so far. Aim of the current study was to determine the value of FCM in liver specimens according to the criteria of the German Society for Organ Procurement (DSO). In this prospective study, conventional histology and FCM scans of 50 liver specimens (60% liver biopsies, 26% surgical specimens, 14% donor samples) were evaluated according to the DSO. Comparison of FCM scans and conventional frozen sections revealed almost perfect levels of agreement for cholangitis (κ = 0.877), fibrosis (κ = 0.843) and malignancy (κ = 0.815). Substantial levels of agreement could be obtained for macrovesicular steatosis (κ = 0.775), inflammation (κ = 0.763), necrosis (κ = 0.643) and steatohepatitis (κ = 0.643). Levels of agreement were moderate for microvesicular steatosis (κ = 0.563). Strength of agreement between frozen sections and FCM was superior to the comparison of conventional HE and FCM imaging. We introduce FCM as a potential alternative to frozen section that may represent a novel approach to liver transplant pathology where timely feedback is crucial, and the deployment of human resources is becoming increasingly difficult.