Biopsy is the removal of a sample of tissue from the body for examination. The tissue is examined under a microscope to assist in diagnosis. Many medical conditions, including all cases of cancer, must be diagnosed by removing a sample of tissue from the patient and sending it to a pathologist for examination.

Any organ in the body can be biopsied using a variety of techniques, some of which require major surgery, while others do not even require local anesthesia (e.g., fine needle aspiration biopsy of thyroid, breast, lung, liver, etc).

After the biopsy specimen obtained by the doctor it is sent for examination to a pathologist in a preservative fluid (formalin). The pathologist prepares a written report after examining the tissues and fluids from the body under a microscope. This information helps the doctor to manage the patient's health condition appropriately.