| Series |
Small invasive cancer of colon and rectum less than 10 mm |
| Title |
A case of type IIa + IIc submucosal invasive colon cancer with so-called "irregular micro pit pattern" observed with magnifying chromoendoscopy |
| Author |
Hisashi Nakamura |
Department of Gastroenterology, Chofu Surgical Clinic |
| Author |
Akihiko Yamamura |
Department of Pathology, Tokyo Metropolitan Tama Cancer Detection Center |
| Author |
Yasuhiro Oono |
Department of Gastroenterology, Tokyo Metropolitan Tama Cancer Detection Center |
| Author |
Yasuhiro Tomino |
Department of Gastroenterology, Tokyo Metropolitan Tama Cancer Detection Center |
| Author |
Yousuke Iriguchi |
Department of Gastroenterology, Tokyo Metropolitan Tama Cancer Detection Center |
| Author |
Jhoji Oda |
Department of Gastroenterology, Tokyo Metropolitan Tama Cancer Detection Center |
| Author |
Masaru Mizutani |
Department of Gastroenterology, Tokyo Metropolitan Tama Cancer Detection Center |
| Author |
Tomoaki Shinohara |
Department of Gastroenterology, Tokyo Metropolitan Tama Cancer Detection Center |
| Author |
Satoshi Takayanagi |
Department of Gastroenterology, Tokyo Metropolitan Tama Cancer Detection Center |
| Author |
Daisuke Kishi |
Department of Gastroenterology, Tokyo Metropolitan Tama Cancer Detection Center |
| Author |
Jun Matumoto |
Department of Surgery, Tokyo Metropolitan Fuchu Hospital |
| [ Summary ] |
A 70-years-old man underwent screening colonoscopy at our clinic. Although he had received a total colonoscopy at another clinic 5 years before, no abnormal findings had been found at that time. Colonoscopy showed a reddish flat elevated lesion, 7 mm in size, in the sigmoid colon. Narrow Band Imaging with magnification revealed dilated abnormal vessels on the surface (irregular in size, complicated branching, disruption and irregular winding), which were classified as capillary pattern type IIIB according to Sano's classification. Chromoendoscopy showed a depressed area in the flat elevated lesion, and thus it was macroscopically classified as type IIa + IIc. Based on the aforementioned endoscopic findings, an endoscopic diagnosis of submucosal deeply invasive cancer was suggested. Furthermore, chromoendoscopy using crystal violet staining with magnification was applied, and a type V irregular pit pattern according to Kudo's classification was identified in the depressed area. However, when pit patterns in the depressed area were carefully reanalyzed, micro-round pits were observed. These pits were different from type IIIL and type IIIs lesions and were irregular in size and in shape. This type of pit pattern was termed "irregular micro pit pattern" and histologically identical to moderately differentiated tubular adenocarcinoma. Despite its small size, the lesion was treated with laparoscopic colectomy, since it was endoscopically diagnosed as a submucosal deeply invasive cancer. The pit pattern of the resected lesion observed by stereomicroscopy was the same as that observed with magnifying chromoendoscopy. Histologically, it was determined to be a moderately differentiated tubular adenocarcinoma, part of which was a poorly differentiated adenocarcinoma extending deeply into the submucosal layer (1,550 Mum in depth). The crypt openings of the moderately differentiated tubular adenocarcinoma, observed on the surface histologically were considered to be identical to the "irregular micro pit pattern" per the proposed definition. Vessel invasion (Iyi, v1) and budding were histologically detected, however, no lymph node involvement (pN0) was found in the resected specimens. The pit patterns observed with magnifying chromoendoscopy were not only useful for prediction of invasion depth preoperatively, but also useful for prediction of histologic subtype of moderately differentiated tubular adenocarcinoma. |