Venous invasion of colorectal cancer, modified histology

Histologic section of a surgically removed colon cancer (stage II adenocarcinoma) stained with Movat's pentachrome stain and subsequently digitally enhanced. A tumour invading a nearby vein is visible in the top centre of the image (grey) surrounded by elastin fibres (dark green) found in the wall of the blood vessel. A blood vessel without tumour is visible in the lower left corner of the image (pink). Tumour spread into surrounding veins (venous invasion) is one of the first and most important steps in the spread of colorectal cancer to distant organs (metastasis). When this feature is identified in surgically removed colorectal cancer specimens, it is associated with a higher rate of distant metastasis and may prompt oncologists to offer chemotherapy. Using an elastin stain allows for far more sensitive and accurate detection of venous invasion by highlighting residual elastin fibres of the vein wall. This is particularly useful when a tumour partially destroys the blood vessel wall that it is invading, making its recognition difficult using conventional stains. An increasing number of pathologists in Canada and the United Kingdom are now routinely using these alternative stains when examining colorectal cancer specimens. Horizontal width of image is approximately 1000 micrometres.