Digital Confocal Microscopy for Real-time Diagnosis of Pancreatic Solid Lesion

Endoscopic ultrasound-guided (EUS) tissue acquisition is the current standard of care for the diagnosis of pancreatic solid lesions. However, EUS-sampling is burdened by a non-negligible risk of non-diagnostic or inconclusive results, with an estimated negative predictive value not higher than 70-80%. ROSE could improve the diagnostic yeld of this procedure. Data about the utility of rapid on-site evalutation (ROSE) are still controversial. Without ROSE, current guidelines suggest performance of three to four needle passes with an fine needle aspiration (FNA) needle or two to three passes with a fine needle biopsy (FNB) needle. Potential drawbacks of ROSE are the considerable time commitment, costs and logistical and personnel issues that arise because of the "on demand" nature of these procedures with the need to have available technologists. Ex-vivo fluorescence confocal laser microscopy (FCM) is an optical technology for rapid microscopic digital imaging of fresh unfixed biological specimens without any slide preparation. FCM involves no damage or cell/tissue loss during the examination and the sample can subsequently be recovered and formalin-fixed and paraffin-embedded (FFPE) for permanent histology. FCM allows both cellular and architectural details to be visualized, similar to standard histological analysis of paraffin-embedded or frozen samples. With FCM, multimodal confocal microscopy using different laser sources and fusion images can generate optical plans similar to those from hematoxylin/eosin (H\&E)- stained sections directly from native tissues. Recently, the feasibility of FCM with MAVIG VivaScope® 2500M-G4 in EUS-FNB sample of pancreatic solid lesions has been investigated . This previous single-center study demonstrated good concordance between the FCM image-based evaluation and the final FFPE histology. However in this first study, a single type of FNB needle was used for all the procedures and the pathologist involved was expert in digital pathology and in pancreatic disease. Therefore it might be not representative of the everyday clinical practice. In addition the first study was mainly focused on the adequacy assessment of the samples.