Iwao Kaneko

Lymphatic Vessel Density at the Site of Deepest Penetration as a Predictor of Lymph Node Metastasis in Submucosal Colorectal Cancer

PurposeLymph node metastasis is an important factor that influences curability after endoscopic treatment of submucosal colorectal cancer. This study was designed to determine the usefulness of identification of lymphatic vessels by immunohistochemistry in predicting lymph node metastasis of submucosal colorectal cancer.MethodsLymphatic involvement was assessed by hematoxylin and eosin staining and podoplanin immunostaining on samples resected from 268 patients with submucosal colorectal cancer. Lymphatic vessel density was estimated by two investigators by average count of three fields (×200) in the area of greatest number of podoplanin-positive capillaries at the site of deepest submucosal penetration. Relations with other clinicopathologic parameters also were investigated.ResultsLesions with high lymphatic vessel density (≥9 vessels per field) showed a significantly greater incidence of lymph node metastasis than did those with low lymphatic vessel density (<9 vessels per field; 23.3 vs. 8.4 percent). By multivariate analysis, lymphatic vessel density was determined to be an independent risk factor for lymph node metastasis of submucosal colorectal cancer (P = 0.0044). Lymphatic vessel density also correlated with tumor budding and the degree of inflammation at the invasive front.ConclusionsIdentification of lymphatic vessels by podoplanin immunostaining provides objective and accurate evaluation of lymphatic involvement. Lymphatic vessel density at the site of deepest penetration is a useful predictor of lymph node metastasis of submucosal colorectal cancer.

PIT PATTERN DIAGNOSIS FOR COLORECTAL NEOPLASIA USING NARROW BAND IMAGING MAGNIFICATION

Narrow band imaging (NBI) is a newly developed technology that uses optical filters for RGB sequential illumination and narrows the bandwidth of spectral transmittance. NBI enables the observation of the fine capillaries in the superficial mucosa of the gastrointestinal tract. In this report, the authors assessed the clinical usefulness of NBI magnification in pit pattern diagnosis for colorectal neoplasia. A total of 90 colorectal lesions including nine cases of hyperplasia, 60 of tubular adenoma and 21 of early carcinoma were analyzed. Histologic diagnosis was undertaken according to World Health Organization classifications. Magnified observation of the lesions was performed using NBI without chromoendoscopy, and pit pattern diagnosis was then recorded. After endoscopic or surgical resection of the lesion, the authors performed stereoscopic examination to confirm the pit pattern. From these data, the authors estimated the ability to diagnose pit patterns using NBI magnification without chromoendoscopy. The correspondence rate of pit pattern diagnosis between NBI magnification without chromoendoscopy and stereoscopic findings was 100% (9/9) for type II, 100% (56/56) for type IIIl, 100% (3/3) for type IV, 80% (12/15) for type Vi, and 57% (4/7) for type Vn. NBI magnification without chromoendoscopy demonstrated good results for pit pattern diagnosis of colorectal neoplasia, especially for lesions with regular pit pattern.

TECHNIQUES AND PITFALLS OF ENDOSCOPIC SUBMUCOSAL DISSECTION FOR COLORECTAL TUMORS

Endoscopic submucosal dissection (ESD) for colorectal tumors is steadily being developed. Safety and standardization of ESD for colorectal tumors have not been yet established because of the technical difficulties and the unsuitable anatomical characteristics of the colon and rectum. The authors mainly use a Flex knife for mucosal incision and a Hook knife for submucosal dissection to perform ESD safely. Skillful colonoscopic control, selection of scope, distal attachment tip hood, adequate high‐frequency generator and correct approach strategy should all be considered for safe performance of ESD. However, the incidence of indicative lesions is rare because the majority of colorectal tumors are adenomatous large laterally spreading tumors, which can be cured by intentional endoscopic piecemeal resection. At present, ESD for colorectal tumors should be performed only at central facilities that have expert colonoscopists. With the development of new devices and associated techniques, technical standardization of ESD for colorectal tumors is expected in the near future.

SUPERFICIAL TYPE SERRATED ADENOMA IN ULCERATIVE COLITIS RESECTED BY ENDOSCOPIC SUBMUCOSAL DISSECTION

A female patient with a 17‐year history of an entire type of ulcerative colitis (UC) showed a superficial elevated lesion in the rectum on surveillance colonoscopy. A standard colonoscopic picture showed a slightly red lesion in the background reticular mucosa in the remission stage of UC after a longstanding chronic inflammation. A chromoendoscopic picture using  indigo  carmine  dye‐spraying  showed  a  distinct  superficial  elevated  lesion  with  slight  marginal  elevation  of  12 mm  in diameter. A magnified view showed a slightly irregular type II pit pattern (Kudo & Tsurutas classification). Ultrasonographic view using a high frequency ultrasound probe (20 MHz) showed that this lesion was confined to the intramucosal layer. As submucosal fibrosis due to previous repeated inflammations made it difficult to perform strip biopsy, an endoscopic submucosal dissection (ESD) method using a Hook knife was undertaken. A completely resected histological specimen showed a serrated adenoma.