Histologic Mimics and Diagnostic Pitfalls of Gastrointestinal Endoscopic Lifting Media, ORISETM gel and Eleview®.

CONTEXT Synthetic lifting media, OriseTM gel and Eleview®, are increasingly utilized in gastrointestinal endoscopy, but neither comparative features nor pitfalls are well-established. OBJECTIVE Media histopathology, morphologic mimics, and complications are described, along with helpful stains and endoscopist media preference. DESIGN A 3-year retrospective search was performed. Pan-mucin, amyloid, and infectious disease stains were performed. Endoscopist lifting media preferences were surveyed. RESULTS 123 cases (108 endoscopies, 15 subsequent surgeries) were identified. Orise gel was used in 86 (79.6%), Eleview in 20 (13.9%), and others in 7 (6.5%). Orise gel was histologically identified in 58.1% (n=50) of endoscopic specimens and all 15 resections. Eleview media was not detected histologically. Orise gel mimicked mucin in H&E-stained biopsies, concerning for adenocarcinoma misdiagnosis and/or upstaging, but did not stain for mucin. Acid fast bacterial staining highlights Orise gel for specific and definitive identification. In resections, Orise evolves into an amorphous eosinophilic material, often with exuberant giant-cell reaction and transmural bowel penetration. Polyp formation lead to polypectomy in one patient, and operative lesions concerning for adenocarcinoma resulted in frozen sections in two patients. Orise gel mimics mucin, malignant masses, amyloid, pulse granulomata, elastofibromas, and infectious granulomata. No significant endoscopist media preference was identified. CONCLUSIONS Recognition of Orise gel in tissues eliminates multiple pitfalls. Eleview was not detectable, yielded none of the pitfalls seen with Orise gel, and on our survey, has equivalent endoscopist acceptance. In this largest published series to date, Eleview is clearly preferable to Orise gel.