Sa1853 A Novel Multiphoton Fluorescent Probe for Nitric Oxide in Colon Neoplasm Tissue

INTRODUCTION: So far endocytoscopy (ECS) has been validated as a diagnostic tool in pre-malignant gastrointestinal conditions. Following our preliminary experience with ECS (Endoscopy. 2007, 39(4);369-70), we started evaluating diagnostic value of optical biopsies obtained by ECS in different clinical settings, including GVHD. Non-invasive optical biopsy techniques, such as confocal laser endomicroscopy or ECS, appear to be the ideal diagnostic tool in patients at high risk for bleeding due to low platelet count. AIMS & METHODS: Aim of our pilot study was to evaluate (a) correlation between ECS and histopathology, and (b) clinical impact of ECS in pts suspected to have early GVHD. From Jan 2010 thru June 2011, we observed 25 consecutive pts (M 17; F 8; mean age, 46±17 yrs) with symptoms (diarrhea, nausea, vomiting) suggesting acute GVHD 96±77 days after bone marrow transplantation. After mucolysis and dye staining with methylen blue, we performed both ECS (XEC-300-U endocytoscope; Olympus Medical System Co., Tokyo, Japan) and biopsies in the rectum at 15 cm, 10 cm, and 5 cm from the anal verge. Video images and H&E slides were evaluated by two experienced endoscopists and two pathologists, respectively. RESULTS: Comparison between ECS and histopathological findings, according to the NIH Consensus Project classification, provided the results showed in the table. Correspondence between ECS and histopatologic diagnosis was found in 18 pts (72%). GVHD was overdiagnosed by ECS in 4 cases (16%) and underdiagnosed in 3 (12%). CONCLUSION: In our experience good results of ECS (sensitivity 82 %, specificity 100%, PPV 85%, NPV 100%) turned to be useful in clinical decision-making process and optimizing therapeutic management, especially due to high reliability for ruling out acute GVHD in symptomatic pts. Should our preliminary results be confirmed by further prospective studies, ECS could be regarded to as an important, non-invasive alternative to endoscopic biopsies or a tool for targeting rectal biopsies leading to diagnosis of acute GVHD safely in patients at high risk for bleeding. table 1