Anatomic (or anatomical) pathology is the branch of medicine that studies the effect of disease on the structure of body organs, both as a whole (grossly) and microscopically. The primary role of anatomic pathology is to identify abnormalities that can help to diagnose disease and manage treatment. Although one of the frequent uses of anatomic pathology is to help identify and manage various types of tumors or cancers, it is also valuable in evaluating other conditions, including kidney and liver diseases, autoimmune disorders, and infections, for example. In fact, in most hospitals, all tissue removed during surgery must be examined by a pathologist.
Anatomic pathology is somewhat different from clinical pathology (or laboratory medicine), which deals with the measurement of chemical constituents of blood and other body fluids (clinical chemistry), analysis of blood cells (hematology), and identification of microorganisms (microbiology), to name a few examples. While most of the tests described on this site would be categorized as clinical pathology, many are used in conjunction with anatomic pathology procedures. In fact, technical advances are blurring the distinctions between the two in many areas. Overlaps include, for example, flow cytometry, cytogenetics and molecular pathology, which can be performed on both tissue samples and blood or body fluid samples. Therefore, some knowledge of this branch of medicine may help you better understand the tests that your or a family member's health practitioner may consider in diagnosing, monitoring, and treating a condition.
There are two main subdivisions within anatomic pathology:
- Histopathology, which involves examination of intact tissue under the microscope. This is often aided by the use of special staining techniques and other associated tests, such as using antibodies to identify different components of the tissue.
- Cytopathology (cytology), which is the examination of single cells or small groups of cells. A common cytology test is the cervical Pap smear. Specimens are processed by physician assistants and technologists and then examined under a microscope by a physician pathologist. The pathologist gives the definitive diagnosis to the health practitioner, who then decides on the most appropriate mode of treatment and patient management.
Anatomic pathologists are also involved in performing post-mortem examinations (autopsies). An autopsy may be performed after a person has died of an illness that could not, for whatever reason, be properly or fully diagnosed before death. The physician will seek consent from the family to have an autopsy performed. If the cause of death is suspicious or related to an illegal activity, the autopsy will be performed by a forensic pathologist. Consent from next of kin is not required for such medico-legal autopsies. (For more on this, see our information page on Forensic Pathology and Autopsies.)