What is Pathology?


Pathology refers to the study of disease including the causes and effects of it. It also comprises of various bioscience research fields and clinical practices. When this term is used in modern medicine, it often has a narrower fashion used to refer to tests and processes in the contemporary medical field where there is disease diagnosis through the analysis of bodily fluid, tissues, and cells. The term “pathology” can also be used to refer to the progression of disease. An individual that practices pathology is known as a pathologist. Generally, pathology involves four components of disease:

  • The cause of disease

  • Pathogenesis – the mechanism of disease development

  • Morphologic changes seen – the structural alterations that may be present during the disease

  • Clinical manifestations – the consequences of the disease

Areas of study include inflammation, necrosis, injury, wound healing, neoplasia, etcetera. Pathologists study cellular patterns under a microscope to determine if a specimen is benign or malignant, employ genetic studies, and assess various diseases using gene markers. 

History of Pathology

The study of pathology dates back to antiquity. In most early societies, there is a rudimentary understanding of various conditions based on records from China, India, and the Middle East. In ancient Greece, the study of disease was ongoing with many notable early physicians such as Hippocrates. These practices were then continued by the Byzantines and Romans. Due to the many areas of scientific inquiry, the growth in this field stagnated after the Classical Eras and gradually developed throughout various cultures. The growth of this field languished until experimentation proliferated in the Renaissance, baroque, and Enlightenment eras due to the resurgence of empirical methods. By the 17th century, the examination of tissues through microscopy led British Royal Society member Robert Hooke to use the term “cell”. Modern pathology developed as a distinct field in the 19th century through physicians and philosophers who study diseases. Formally, it was not recognized as an area of specialty until the late 19th to early 20th centuries. In the 19th century, physicians start understanding disease-causing pathogens such as viruses, bacteria, prions, parasites, and fungi existed and has the capability to multiply. With new understanding, there was a comparison of symptoms leading to the realization of replication and varied effects each disease can have on the human host. In the late 1920s to early 1930s, pathology became a medical specialty. By the 20th century, pathology can be divided into rarefied fields.

Types of Pathology

Pathology can be divided into subdisciplines. 

  1. Anatomical pathology – this medical specialty is concerned with disease diagnosis based on the gross, microscopic, immunologic, chemical, and molecular examination of tissues, organs, or whole bodies. It can again be divided into:

  1. Surgical pathology – A significant and time-consuming specialty with a primary focus on examining tissues for a definitive diagnosis. Specimens are received as core biopsies, small skin biopsies, etcetera where gross and histologic tissue analysis are assessed by laboratory tests in immunohistochemistry. An autopsy is performed by a pathologist to determine the cause of death, state of health before death, and medical diagnosis and treatment before death.

  2. Cytopathology – A branch of pathology studying diseases on the cellular level. It is mostly used in the diagnosis of cancer, but it can also aid in the diagnosis of infectious diseases and inflammatory conditions. It is usually used on free cells or fragments that exfoliate or can be removed through fine needle aspiration or abrasion.

  3. Molecular pathology – This is a recent discipline that has made great progress in the last decade. It involves the diagnosis and study of disease via molecular examination of bodily fluids, tissues, and organs. Various diseases such as cancer can be due to alterations in the genetic code, mutations, and identification of specific hallmark mutations which allow professionals to diagnose and choose specific treatment. Molecular pathology is a discipline that paves the way for personalized medicine through the prediction of patient response to treatment based on genetic make-up. It also involves the development of genetic and molecular approaches to classification, diagnosis, design, and validation of predictive biomarkers for disease prognosis and susceptibility of cancer development. The high levels of sensitivity allow the detection of small tumors that are otherwise undetectable. This leads to improved care, earlier diagnosis, and better prognosis.

Training and Accreditation

The accreditation needed to be a pathologist varies based on country. In the United States, pathologists are required to complete a four-year undergraduate program, four years of medical school, and another three to four years of postgraduate training. Per the American Board of Pathology, training can be within two specialties: anatomical pathology and clinical pathology. The American Osteopathic Board of Pathology recognizes four pathologies: dermatopathology, forensic pathology, anatomic pathology, and laboratory medicine. In the United Kingdom, the training to be a pathologist is licensed by the UK General Medical Council under the oversight of the Royal College of Pathologists. After undergraduate medical study lasting four to six years, trainees go on to a two-year program. 


  1. Pathology. Wikipedia. Accessed 8/28/2019. https://en.wikipedia.org/wiki/Pathology

  2. What is pathology. McGill. Accessed 8/28/2019. https://www.mcgill.ca/pathology/about/definition