Histologic mimics and diagnostic pitfalls of gastrointestinal endoscopic lifting media, ORISE™ gel and Eleview®.

Synthetic lifting media, ORISE™ gel and Eleview®, are increasingly used in gastrointestinal endoscopy, but neither comparative features nor pitfalls are well-established. Media histopathology, morphologic mimics, and complications are described, along with helpful stains and endoscopist media preference. A 3-year retrospective search was performed. A total of 123 cases (108 endoscopies and 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 were not detected histologically. ORISE gel mimicked mucin in hematoxylin and eosin-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 leads 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. 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.

Potential clinical complications of Orise™ gel use, a new submucosal lifting agent: experience from a tertiary care center and review of the literature.

Background: Endoscopic mucosal resection (EMR) involves forming a fluid cushion in the submucosal area with a lifting agent, followed by superficial resection. Orise™ gel is one of the commonly used lifting agents for EMR. We present a case series and literature review that analyzes the characteristic histopathological findings and clinical implications observed where Orise™ gel was used before EMR. Methods: Colon resection specimens and prior EMR specimens where Orise™ gel was used were reviewed for patients undergoing EMR between January 2018 and December 2020. The literature review included relevant studies from the Medline and Cochrane databases from January 2018 to December 2020. Results: A total of 12 colon polyp EMRs using Orise gel were performed during the study period. Seven patients (58.34%) underwent surgical resection. Histological examination revealed that, after the EMR procedure, the Orise™ gel material changed its morphological characteristics over time from a basophilic (bluish) non-inflamed pattern to an eosinophilic (pink) type pattern, eliciting a foreign body reaction. The endoscopic appearance and examination of the excised specimens weeks after injection gave the impression of a mass in some cases. The material was also present transmurally and in some cases in the peri-intestinal adipose tissue. Conclusions: It was observed that Orise™ gel use elicits a foreign body-type granulomatous reaction. This potential side effect may lead to overdiagnosis of a mass/lesion and unnecessary surgical interventions. This case series and review of the literature aims to increase awareness of the changes caused by Orise™ gel in the gastrointestinal tract.

Lifting Agent Granuloma: Histologic Findings Following Use of ORISE Gel for Endoscopic Resections in the Gastrointestinal Tract

OBJECTIVES: Histologic findings after endoscopic resection using submucosal lifting agents Eleview and ORISE gel are described. METHODS: Four cases were identified based on the histologic presence of ORISE gel. Cases were selected to illustrate the histologic appearance of the lifting agent immediately after injection (day 0) and after an interval of approximately 2 months. RESULTS: Immediately after injection, the gel had an appearance similar to acellular mucin on H&E stain and showed mucicarmine positivity but was negative for periodic acid-Schiff stain and Alcian blue. At 2 months, the appearance changed drastically and was characterized by a hard, homogenous eosinophilic quality and elicited a robust foreign body-type giant cell reaction; we have proposed the name lifting agent granuloma for this histologic appearance. The aged material may be mistaken for amyloid or a pulse (legume) granuloma; however, the material was negative on Congo red stain and had a different clinical history and distribution in the tissue from those of a pulse granuloma. CONCLUSIONS: It is important to take note of the histologic appearance of these new submucosal lifting agents over a varying time interval, as outlined here, so that they are readily recognized and not mistaken for other entities.