Hydrogen peroxide-related colitis (previously known as "pseudolipomatosis"): a series of cases occurring in an epidemic pattern.

We report several cases of hydrogen peroxide-related colitis that occurred in an epidemic pattern in our gastrointestinal endoscopy center during a 2-month period in early 2007. During colonoscopy using sterilized endoscopes that had been flushed with hydrogen peroxide after the peracetic acid cycle, instantaneous effervescence and blanching (the "snow white sign") were observed on the intestinal mucosa when the water button was depressed. Biopsy specimens revealed features resembling a clinical condition which used to be known as "pseudolipomatosis." At follow-up, no patient was found to have suffered morbidity associated with this peroxide colitis. Endoscopists should consider hydrogen peroxide colitis when they see a snow white sign during colonoscopy which cannot be attributed to active inflammation or organic disease of the digestive tract.