title: Effect of skip lymphovascular invasion on hepatic metastasis in colorectal carcinomas.
abstract: BACKGROUND
  "Skip" lymphovascular invasion presenting as discontinuous foci of tumor cells within the colon wall is now excluded from consideration when determining T stage in the TNM classification. The purpose of this study was to assess the clinicopathological characteristics of colorectal cancer (CRC) patients with such skip lymphovascular invasion.
  
  
  METHODS
  First, a retrospective questionnaire survey of the incidence of skip lymphovascular invasion was performed for a total of 1,868 patients with CRCs at ten institutions. Next, we comparatively assessed clinicopathological data for 896 CRC patients with or without skip lymphovascular invasion.
  
  
  RESULTS
  The incidence of skip lymphovascular invasion was 1.1 % (20 out of 1,868). Most of the affected cases were rectal, pT2, and node negative, with moderately differentiated histology. Skip lymphovascular invasion was present in the muscularis propria and subserosa, with the tumors directly invading submucosa (pT1) or muscularis propria (pT2). Hepatic metastasis was greater in CRC with skip lymphovascular invasion (25 %) than in pT1/2 CRC (0 %; P < 0.001) or pT3 CRC without such invasion (13.8 %; P = 0.185).
  
  
  CONCLUSIONS
  Our study suggests that skip lymphovascular invasion is associated with hepatic metastasis in CRC cases. Thus, definition of a T category including such invasion would be useful for clinical practice.
authors.affiliation: Division of Gastroenterology and Hepatology, Department of Internal Medicine, Toho University Omori Medical Center, 6-11-1 Omorinishi, Ota-ku, Tokyo, 143-8541, Japan.
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Okamoto
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Mitomi
authors.forename: Kazuhito
authors.initials: K
authors.lastname: Ichikawa
authors.forename: Shigeki
authors.initials: S
authors.lastname: Tomita
authors.forename: Takahiro
authors.initials: T
authors.lastname: Fujimori
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Igarashi
mesh_terms: D000230:Adenocarcinoma / Q000473:pathology* / Q000556:secondary; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015179:Colorectal Neoplasms / Q000473:pathology*; D005260:Female; D006801:Humans; D008113:Liver Neoplasms / Q000473:pathology* / Q000556:secondary; D008198:Lymph Nodes / Q000473:pathology; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D009367:Neoplasm Staging; D012189:Retrospective Studies; D019043:Vascular Neoplasms / Q000473:pathology* / Q000556:secondary; D055815:Young Adult