Early Colon Cancer That Changed Its Morphology Twice.

A 65-year-old man had previously been diagnosed to have a flat lesion measuring 15 mm in diameter (Picture 1) in the transverse colon. He was referred to our hospital because snaring proved to be difficult after pure saline injection.

Picture 1.

At 60 days after being transferred to our institution, a second colonoscopy revealed a nodular protrusion in a shallow depression (Picture 2), thus suggesting the possibility of deep submucosal invasion (1). However, magnifying narrow-band imaging (NBI) showed a caliber change and an uneven vessel distribution, which corresponded with the Japan NBI Expert Team classification of type 2B disease.

Picture 2.

At 92 days after admission, a third colonoscopy before endoscopic submucosal dissection revealed that the nodular protrusion had disappeared and the macroscopic type had changed from IIc+Is to IIa (Picture 3). A histopathological analysis showed minute submucosal cancer invasion (SM1: 230 μm) and partial submucosal fibrosis (Picture 4).

Picture 3.

Picture 4.

Stimulation by submucosal injection may have induced inflammation followed by fibrosis (2). We hypothesized that the submucosal inflammation reaction had thus caused the protrusion, and thereafter the protrusion gradually diminished along with the remission of inflammation.

The authors state that they have no Conflict of Interest (COI).