In pathology, benign is used to describe a non-cancerous growth such as a tumour. It can also be used to describe normal tissue. The opposite of benign is malignant.
A benign tumour is a large group of non-cancerous cells that are growing faster than the normal cells around them. Because they are growing faster than the normal cells, the tumour cells form a mass that stands out from the surrounding tissue.
While benign tumours can still cause damage by compressing nearby structures, such as other organs, nerves, or blood vessels, the cells cannot typically spread to other parts of the body. The movement of tumour cells to another part of the body is called metastasis and this is usually only seen with malignant (cancerous) tumours.
One of the most important decisions a pathologist has to make every day is deciding whether a tumour is benign or malignant. To help them make this decision, pathologists examine a sample of the tumour under the microscope and look for the following features: