by Jason Wasserman MD PhD FRCPC
June 1, 2022
Dysplasia is a precancerous change that can happen anywhere in the body. The cells in an area of dysplasia show an abnormal pattern of growth and maturation. This change can only be seen when the tissue is examined under the microscope.
The cause depends on where in the body the dysplasia is found and the types of cells involved. Some common causes include infection with human papillomavirus (HPV) in the cervix, smoking and excessive alcohol consumption in the oral cavity (mouth and tongue) and larynx (throat), prolonged exposure to the sun on the skin, and a combination of genetic and environmental factors in the colon.
Pathologists divide dysplasia into different levels called grades and several systems are used to describe the grade. In some parts of the body, the grade is divided into two levels: low-grade dysplasia and high-grade dysplasia. Dysplasia caused by human papillomavirus (HPV) is also divided into two levels called low-grade squamous intraepithelial lesion (LSIL) and high-grade squamous intraepithelial lesion (HSIL). In other parts of the body, the grade is divided into three levels: mild dysplasia, moderate dysplasia, and severe dysplasia.
The level or grade of dysplasia is very important because higher grades (for example high-grade dysplasia and severe dysplasia) are more likely to turn into cancer over time. In contrast, the risk of developing cancer with lower grades (for example low-grade dysplasia and mild dysplasia) is much less.