Pathologists use the words cyst to describe an abnormal open space surrounded by a thin wall of tissue. The space can be empty (filled with air) or it can be filled with another type of tissue such as blood, pus (dead immune cells), or skin.
Cysts that have only a single open space are called unilocular while those with multiple smaller spaces are called multilocular.
Cysts can start anywhere in the body. The most common locations are the ovaries and skin. Cysts can range in size from very small (only seen under the microscope) to very large (big enough to be seen without a microscope).
Cyst is a descriptive word which can be applied to many pathological situations. It is not a diagnosis in itself. In many cases, a cyst is a non-cancerous (benign) growth. However, cysts can also be seen in a cancer.
The behavior of the cyst depends on the location of the cyst and the type of cells making the cyst. Your pathologist will examine the cyst under the microscope and provide this information in your pathology report.