title: Early stage signet ring cell carcinoma of the colon examined by magnifying endoscopy with narrow-band imaging: a case report.
abstract: BACKGROUND
  Signet ring cell carcinoma of the colon and rectum is rare, and most cases are detected at an advanced stage. We present a case of primary signet ring cell carcinoma detected at an early stage by magnifying endoscopy with narrow-band imaging (NBI) and crystal violet staining.
  
  
  METHODS
  A 73-year-old man visited our hospital for screening colonoscopy. Six years previously, he had undergone endoscopic submucosal dissection (ESD) for early gastric cancer. The pathological diagnosis was a well-differentiated adenocarcinoma, invading into the mucosa without lymphovascular invasion. Colonoscopy revealed a flat elevated lesion with a slightly depressed area, 20 mm in diameter, in the cecum. Further, magnifying endoscopy with NBI revealed that the surface pattern was slightly irregular and microvessels had a regular diameter and distribution in the margin of the lesion, but in the central part of the lesion, irregularity in the tumor surface pattern and form as well as in the diameter and distribution of microvessels was noted. Additionally, due to mucus, avascular areas were also observed. Magnifying endoscopy combined with 0.05 % crystal violet staining showed IIIL and VI pit patterns in the margin of the lesion, and a VI pit pattern in the central part of the lesion; however, due to mucus exudate, this finding could not be established with certainty. The lesion was successfully removed en bloc using ESD without complications. The tumor was composed mainly of signet ring cell carcinoma, partially mixed with moderately differentiated (tub2) and well-differentiated (tub1) adenocarcinomas. The tumor cells infiltrated 250 μm into the submucosal layer and involved lymphatic vessels. Therefore, the patient underwent an additional laparoscopic ileocecal resection, and the resected specimen revealed no residual carcinoma or lymph node metastasis.
  
  
  CONCLUSIONS
  In this case report, we present a case of primary signet ring cell carcinoma detected at an early stage and identified by magnifying endoscopy with NBI and crystal violet staining.
authors.affiliation: Department of Gastroenterology and Hepatology, Nagasaki University Hospital, 1-7-1 Sakamoto, Nagasaki, Japan. k-ohnita@nagasaki-u.ac.jp.
authors.forename: Ken
authors.initials: K
authors.lastname: Ohnita
authors.affiliation: Department of Gastroenterology and Hepatology, Nagasaki University Hospital, 1-7-1 Sakamoto, Nagasaki, Japan. hajimei2002@yahoo.co.jp.
authors.forename: Hajime
authors.initials: H
authors.lastname: Isomoto
authors.affiliation: Department of Gastroenterology and Hepatology, Nagasaki University Hospital, 1-7-1 Sakamoto, Nagasaki, Japan. fuk_naga_ta23@yahoo.co.jp.
authors.forename: Taro
authors.initials: T
authors.lastname: Akashi
authors.affiliation: Department of Gastroenterology and Hepatology, Nagasaki University Hospital, 1-7-1 Sakamoto, Nagasaki, Japan. cbpqc121@yahoo.co.jp.
authors.forename: Keiichi
authors.initials: K
authors.lastname: Hashiguchi
authors.affiliation: Department of Gastroenterology and Hepatology, Nagasaki University Hospital, 1-7-1 Sakamoto, Nagasaki, Japan. matsu7281978@yahoo.co.jp.
authors.forename: Kayoko
authors.initials: K
authors.lastname: Matsushima
authors.affiliation: Department of Gastroenterology and Hepatology, Nagasaki University Hospital, 1-7-1 Sakamoto, Nagasaki, Japan. le7novembre@gmail.com.
authors.forename: Hitomi
authors.initials: H
authors.lastname: Minami
authors.affiliation: Department of Gastroenterology and Hepatology, Nagasaki University Hospital, 1-7-1 Sakamoto, Nagasaki, Japan. akazaway@nagasaki-u.ac.jp.
authors.forename: Yuko
authors.initials: Y
authors.lastname: Akazawa
authors.affiliation: Department of Gastroenterology and Hepatology, Nagasaki University Hospital, 1-7-1 Sakamoto, Nagasaki, Japan. naoyuki3334@hotmail.com.
authors.forename: Naoyuki
authors.initials: N
authors.lastname: Yamaguchi
authors.affiliation: Department of Gastroenterology and Hepatology, Nagasaki University Hospital, 1-7-1 Sakamoto, Nagasaki, Japan. ftake@nagasaki-u.ac.jp.
authors.forename: Fuminao
authors.initials: F
authors.lastname: Takeshima
authors.affiliation: First Department of Surgery, Nagasaki University Hospital, 1-7-1 Sakamoto, Nagasaki, Japan. tokazu@nagasaki-u.ac.jp.
authors.forename: Kazuo
authors.initials: K
authors.lastname: To
authors.affiliation: First Department of Surgery, Nagasaki University Hospital, 1-7-1 Sakamoto, Nagasaki, Japan. takehiro@nagasaki-u.ac.jp.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Takeshita
authors.affiliation: Department of Pathology, Nagasaki University Hospital, 1-7-1 Sakamoto, Nagasaki, Japan. y-haruna@nagasaki-u.ac.jp.
authors.forename: Haruna
authors.initials: H
authors.lastname: Yasui
authors.affiliation: Department of Pathology, Nagasaki University Hospital, 1-7-1 Sakamoto, Nagasaki, Japan. abek@nagasaki-u.ac.jp.
authors.forename: Kuniko
authors.initials: K
authors.lastname: Abe
authors.affiliation: Department of Gastroenterology and Hepatology, Nagasaki University Hospital, 1-7-1 Sakamoto, Nagasaki, Japan. kazuhiko@nagasaki-u.ac.jp.
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Nakao
mesh_terms: D000368:Aged; D018279:Carcinoma, Signet Ring Cell / Q000473:pathology*; D003110:Colonic Neoplasms / Q000473:pathology*; D003113:Colonoscopy / Q000379:methods*; D055088:Early Detection of Cancer / Q000379:methods; D005840:Gentian Violet; D006801:Humans; D008297:Male; D062048:Narrow Band Imaging / Q000379:methods*; D013194:Staining and Labeling / Q000379:methods
chemical_list: D005840:Gentian Violet