title: Morphological change of a laterally spreading rectal tumor over a short period.
abstract: BACKGROUND
  Laterally spreading tumors (LSTs) are generally defined as superficial lesions ≥10 mm in diameter that typically extend laterally rather than vertically along the colonic wall. LSTs are usually categorized into 2 subtypes: granular type and nongranular type. Large nodules or depressed areas in granular-type LSTs (LST-Gs) are endoscopic findings of a cancerous component and sometimes represent submucosal invasion. However, the lateral growth and development of LST-Gs remains unclear.
  
  
  METHODS
  This case report describes a case of 79-year-old woman who underwent total colonoscopy due to a positive fecal occult blood test and was detected a LST-G, about 30 mm in diameter in the lower rectum. The lesion consisted of not only aggregated small and large nodules typically seen in LST-Gs but also the hardly elevated flat parts. In the flat part, there were dilated round pits and no evident capillary vessels. Three months later, the flat part increased in height, the dilated round pits were partly replaced by type IIIL pits, and capillary vessels were evident. The lesion was removed by endoscopic submucosal dissection, and diagnosed pathologically as tubular adenoma. We performed the sequence analyses on KRAS, BRAF, NRAS and PIK3CA genes in flat part and nodular part separately, and a mutation of KRAS gene at codon 146 was observed at only nodular part, suggesting probable that nodular part be a precancerous lesion.
  
  
  CONCLUSIONS
  This is a unique and suggestive case, providing information on progression of LST-Gs at the very early stage to carcinogenesis.
authors: Department of Gastroenterology, National Cancer Center Hospital East, Kashiwa City, Chiba, Japan. hidemyam@fc.kuh.kumamoto-u.ac.jp
authors: Hideaki
authors: H
authors: Miyamoto
authors: Yasuhiro
authors: Y
authors: Oono
authors: Kuang-l
authors: KL
authors: Fu
authors: Hiroaki
authors: H
authors: Ikematsu
authors: Satoshi
authors: S
authors: Fujii
authors: Takashi
authors: T
authors: Kojima
authors: Tomonori
authors: T
authors: Yano
authors: Atsushi
authors: A
authors: Ochiai
authors: Yutaka
authors: Y
authors: Sasaki
authors: Kazuhiro
authors: K
authors: Kaneko
mesh_terms: D000236:Adenoma / Q000473:pathology*; D000368:Aged; D003113:Colonoscopy; D018450:Disease Progression; D005260:Female; D006801:Humans; D062048:Narrow Band Imaging; D012004:Rectal Neoplasms / Q000473:pathology*; D013997:Time Factors
references: Gastrointest Endosc. 2008 Oct;68(4 Suppl):S3-47
references: 18805238
references: Cancer Res. 1998 Aug 1;58(15):3289-93
references: 9699657
references: Am J Gastroenterol. 2000 Jul;95(7):1794-9
references: 10925987
references: Endoscopy. 2011 Feb;43(2):100-7
references: 21165823
references: Gut. 2004 Sep;53(9):1334-9
references: 15306595
references: Br J Cancer. 2001 Sep 1;85(5):692-6
references: 11531254
references: Cancer. 1995 Feb 15;75(4):953-7
references: 7842415
references: World J Surg. 1997 Sep;21(7):694-701
references: 9276699
references: Br J Cancer. 2009 Aug 18;101(4):715-21
references: 19603018
references: Lancet Oncol. 2010 Aug;11(8):753-62
references: 20619739
references: Endoscopy. 2001 Apr;33(4):367-73
references: 11315901
references: J Natl Cancer Inst. 1998 May 6;90(9):675-84
references: 9586664
references: Endoscopy. 2001 Aug;33(8):682-6
references: 11490384
references: Dig Endosc. 2011 May;23 Suppl 1:112-5
references: 21535215
references: Cancer Biol Ther. 2006 Aug;5(8):928-32
references: 16969076