Adverse tissue reactions to ORISE gel during endoscopic mucosal resection and dissection.

Background: Submucosal injection of lifting agents (LAs) is frequently used to facilitate endoscopic mucosal resection or endoscopic submucosal dissection. ORISE (Boston Scientific Corporation) gel, approved in 2018 by the United States Food and Drug Administration, has been commonly used until recently. Its use proliferated because of its practical prefilled syringe, prolonged lift effect, and ideal coloration. However, it has been noted to cause unexpected tissue reactions, described as "giant cell reaction" (GCR), which can obscure macroscopic and microscopic views, potentially interfering with pathologic evaluation. This study aimed to describe the adverse effects of ORISE gel.

Methods: This retrospective study analyzed pathologic specimens from all consecutive patients who received ORISE injections for attempted polyp removal and subsequently underwent segmental colon resection at our center between 2019 and 2022. A descriptive analysis was performed.

Results: A total of 45 patients were included, of whom 17 (38.0%) were female and the median age was 66 years. The indications for surgery included adenocarcinoma in 14 patients (31%), suspected malignancy in 3 patients (7%) who had benign GCR-induced masses, and other indications in 28 patients, such as large polyps or recurrent polyps after initial endoscopic treatment. Surgical procedures included right hemicolectomy (44%), low anterior resection (13%), left colectomy (11%), sigmoidectomy (7%), and abdominoperineal resection (4%). Histologic evidence of previous LA injection was seen in 31 patients (69%), with 24 patients exhibiting GCR. At final pathology, no residual neoplasm was found in 9 patients (18%); however, 14 patients (31%) had adenocarcinoma (T1 [7], T2 [3], T3 [3], and T4 [1]).

Conclusion: ORISE gel interacts with various tissue layers of the colon, frequently resulting in GCR. This reaction and the potential subsequent mass effect formation can affect decision-making regarding the management of complex colorectal lesions. Further study into the causes and consequences of LA tissue reactions is warranted.