A biopsy is a medical test commonly performed by a surgeon, interventional radiologist, or an interventional cardiologist involving sampling of cells or tissues for examination.It is the medical removal of tissue from a living subject to determine the presence or extent of a disease.he tissue is generally examined under a microscope by a pathologist, and can also be analyzed chemically. When an entire lump or suspicious area is removed, the procedure is called an excisional biopsy.