A tumour is an abnormal growth made up of cells that push the surrounding normal tissue out of way as it grows. It does not mean the same thing as cancer. A tumour can be either benign (non-cancerous) or malignant (a cancer).
The behavior of a tumour depends on its location in the body, the cells that make up the tumour, and whether the it is benign or malignant.
Some benign tumours can grow to become very large. However, most are unable to spread to other parts of the body. In contrast, malignant tumours have the ability to spread into surrounding tissues or other parts of the body.
One of the most important roles that a pathologist plays in your medical medical care is determining whether a tumour is benign or malignant. By examining tissue from the tumour under the microscope, pathologists can reliably tell the difference between benign and malignant in most circumstances.
Features that are commonly seen in malignant tumours but not in benign tumours include: