Snow white sign. An unusual colitis

A 72-year-old male undergoing a colonoscopy (Fig. 1) as a result of constipation was found to have a 5-mm flat polyp, which was removed. When water was instilled to aid recovery, we became aware of the sudden appearance of whitish lesions (Fig. 2).

Figure 1.

Ascending colon segment with excellent preparation, Boston 3/3/3, after instillation of water.

Figure 2.

Snow white sign. Multiple whitish foamy plaques, some converging, confined to the ascending (A) and transverse colon (B), after instillation of water, with traces of peracetic acid in the endoscope channels.

The “snow white sign” corresponds to colonic pseudolipomatosis, a rare iatrogenic colitis with an aetiology related to residues of disinfectant solutions, in our case peracetic acid, in the channels of the endoscope. Histologically, small gas cysts in the lamina propria, similar to fat, are striking, differing from lipomatosis by the absence of lipids; hence the name. Patients are asymptomatic and lesions disappear spontaneously within 3–20 months.^1,2

The variety of lesions of diverse aetiology we come across means it is essential to have a large atlas to help us correctly characterise the endoscopic patterns and adopt the most appropriate action. The importance of this case therefore lies, on the one hand, in the need to be aware of this unusual and striking benign lesion and not to confuse it with other similar lesions, such as pseudomembranous colitis, colonic lipomatosis or malakoplakia, and, on the other, in our obligation to have an adequate protocol for cleaning, disinfection and rinsing of equipment, in order to avoid such occurrences.

Ethical considerations

The work was conducted in accordance with the Code of Ethics of the World Medical Association.

Funding

None.

Conflicts of interest

None.