Inverted colonic diverticulum.

A 55-year-old African man with no significant medical history presented for intermittent left flank pain and constipation. These symptoms persisted for approximately two months without other clinical sign. Physical examination findings and routine laboratory tests were normal. During colonoscopy, a 0.5 cm polypoid lesion was found in the descending colon. The polypoid structure showed shiny pink mucosa indistinguishable from surrounding normal mucosa, with circumferential pale rings, and it changed appearance according to low (Fig. 1) or high (Fig. 2) insufflation degree.

Figure 1

Endoscopic view of the lesion under low air insufflation

Figure 2

Lesion under high air insufflation

With mild forceps probing, the lesion was reduced, attesting to be an inverted diverticulum. Antispasmodic drugs and high-fiber diet were initiated with two-year favorable evolution.

Inverted colonic diverticula (ICD) are rare and occur in approximately 0.7% of people. They often appear indistinguishable from colon polyps which can lead to dangerous procedures. However, some maneuvers can help diagnose ICD, such as attempting to revert the lesion with forceps [1], or air insufflation [2]; the water jet deformation sign [3]; the “radiating pillow sign”; and, most recently, the concentric pale rings surrounding the lesion (Aurora rings).

The possibility to find an inverted diverticulum during colonoscopy must be considered carefully for correct diagnosis and to avoid unsafe procedures such as biopsy or polypectomy.