Anatomical Pathology is the branch of pathology that deals with the tissue diagnosis of disease. For this, Anatomical Pathologists need a broad-based knowledge and understanding of the pathological and clinical aspects of many diseases.
The tissue on which the diagnosis is made may be biopsy material taken from a patient in the operating theatre, on the ward or from an autopsy (post-mortem). The latter is a small but important component of the work for establishing the cause in cases of sudden or unexpected death, for examining disease progression, including the response to treatment or lack of a response, and in criminal cases (forensic pathology) helping police in their investigations. The work of most Anatomical Pathologists is, however, on tissue from living patients. A large part of this is the detection and diagnosis of cancer. A tissue diagnosis is essential before starting treatment involving major surgery, radiation or drugs, treatments which may have major side effects.
Modern Anatomical Pathologists examine not only samples of solid tissue, but also small specimens of separated cells. This is the subspecialty of Cytology. The specimens include fluids and tissue smears mainly for diagnosis and prevention of cancer. The pathologist collects some of these samples themselves, for example, for the diagnosis of cancer of the breast or the prostate. Often this means that a certain diagnosis can be made before the patient has left the clinic. New methods also allow samples of either separated cells or small tissue fragments to be obtained from organs, such as the pancreas, situated deep within body cavities.