title: Lymphatic vessels in colorectal cancer and their relation with inflammatory infiltrate.
abstract: OBJECTIVE
  The aim of this study was to determine why colorectal tumors confined to submucosa rarely metastasize. Under normal conditions, the submucosa contains many large lymphatic vessels with thin walls that would presumably favor the spread of cancer cells through the lymphatic system.
  
  
  METHODS
  Specimens of colorectal cancer tissue, the border between tumor and normal tissue, and normal tissue were obtained from patients undergoing radical resection of colorectal cancer. The material was embedded in methacrylate resin for light microscopy and Epon for transmission electron microscopy examination. Light microscopy observations were routinely performed on serial sections.
  
  
  RESULTS
  No lymphatic vessels were ever found in the tumor mass. The border area contained peritumoral inflammatory infiltrate of variable thickness. Where submucosal lymphatic vessels came into contact with peritumoral inflammatory infiltrate, they were profoundly altered: their endothelium was fragmented, and their walls were disrupted. These altered lymphatic vessels were almost always accompanied by mast cells, which were observed in the process of degranulating toward the lymphatic endothelium. No such alterations were detected in blood vessels.
  
  
  CONCLUSIONS
  Our results suggest that mast cells, probably influenced by inflammatory infiltrate and/or colorectal cancer cells, destroy lymphatic vessels, which prevents cancer cells from spreading through the lymphatic system.
authors.affiliation: Dipartimento di Neuroscienze, Sezione di Medicina Molecolare, University of Siena, Siena, Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Sacchi
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Weber
authors.forename: Margherita
authors.initials: M
authors.lastname: Aglianó
authors.forename: Paola
authors.initials: P
authors.lastname: Lorenzoni
authors.forename: Antonella
authors.initials: A
authors.lastname: Rossi
authors.forename: Anna Maria
authors.initials: AM
authors.lastname: Caruso
authors.forename: Remo
authors.initials: R
authors.lastname: Vernillo
authors.forename: Renato
authors.initials: R
authors.lastname: Gerli
authors.forename: Marco
authors.initials: M
authors.lastname: Lorenzi
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D015179:Colorectal Neoplasms / Q000473:pathology* / Q000648:ultrastructure; D005260:Female; D006801:Humans; D008207:Lymphatic Metastasis / Q000648:ultrastructure; D008208:Lymphatic System / Q000473:pathology* / Q000648:ultrastructure; D008297:Male; D008407:Mast Cells; D008854:Microscopy, Electron; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D009367:Neoplasm Staging