An erosion is the loss of cells on the surface of a tissue. Another word for erosion is erosive. Erosions are commonly seen on the skin, inside the mouth and throat, and in the digestive tract.
When examined under the microscope, the cells that are normally seen on the surface of the tissue will be missing. The tissue surrounding the erosion may show a number of microscopic changes, including inflammation and hemorrhage (bleeding). A specialized type of tissue called granulation tissue may be seen directly below the erosion. Granulation tissue develops after an injury and it helps the tissue heal. Pathologists sometimes describe the cells surrounding an erosion as showing reactive changes or reactive atypia. This means that the cells look abnormal but are not cancerous.
An erosion may be caused by any process that damages the cells on the surface of a tissue. Common causes include trauma, infection, chronic inflammation, and radiation treatment. A tumour under the surface of tissue may also cause an erosion, however, this is much less common. Some erosions in the colon are a sign of inflammatory bowel disease such as ulcerative colitis or Crohn’s disease.