Significations et usages de Pathology

  A renal cell carcinoma (chromophobe type) viewed on a hematoxylin & eosin stained slide

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Pathology is the precise study and diagnosis of disease. The word pathology is from Ancient Greek πάθος, pathos, "feeling, suffering"; and -λογία, -logia, "the study of". Pathologization, to pathologize, refers to the process of defining a condition or behavior as pathological, e.g. pathological gambling. Pathologies is synonymous with diseases. The suffix "path" is used to indicate a disease, e.g. psychopath.

Pathology addresses 4 components of disease: cause/etiology, mechanisms of development (pathogenesis), structural alterations of cells (morphologic changes), and the consequences of changes (clinical manifestations).^[1]

Pathology is further separated into divisions, based on either the system being studied (e.g. veterinary pathology and animal disease) or the focus of the examination (e.g. forensic pathology and determining the cause of death).

General pathology is a broad and complex scientific field which seeks to understand the mechanisms of injury to cells and tissues, as well as the body's means of responding to and repairing injury. Areas of study include cellular adaptation to injury, necrosis, inflammation, wound healing, and neoplasia. It forms the foundation of pathology, the application of this knowledge to diagnose diseases in humans and animals.

The term general pathology is also used to describe the practice of both anatomical and clinical pathology.

  The History of Pathology

  Pathologist at work

The history of pathology can be traced back to antiquity when people began examining bodies. The examination of bodies led to the dissection of bodies in order to justify the cause of death. During that time, the people already began formulating today what we know as inflammation, tumors, boils, and much more.^[2]

Pathology began to develop as a subject during the 19th Century through teachers and physicians that studied pathology. They referred to it as “pathological anatomy” or “morbid anatomy.” However, pathology as a field of medicine was not recognized until the late 19th and early 20th centuries. In the 19th century, physicians realized that disease-causing pathogens, germs, created themselves and that symptoms were not the vital characteristics of a disease. Through the new information gathered regarding germ reproduction, physicians began to compare the characteristics of one germ’s symptoms as they developed within an affected individual to another germ’s characteristics and symptoms. This realization led to the foundational understanding that diseases are able to create themselves, and that they can affect human beings in unique ways. In order to determine causes of diseases, medical experts used the most common and widely accepted assumptions or symptoms of their times. This is true for those in the past and today.^{[3] [4]}

What set pathology apart from other specialties was the ability to determine a symptom with the naked eye. During the 19th century, Rudolf Virchow gave the biggest contribution to the field by introducing the procedure of analyzing tissue and cells through a microscope to pathologists. This greatly affected the discipline because it was another way to analyze objects, and it led to more advanced technological developments.

By the late 1920s to early 1930s pathology was deemed a medical specialty. ^[5] During the years following, the decision to split pathology in to sub-specialties arose. Today, anatomical, clinical, molecular, plant, forensic, oral, veterinary, dermatopathology, hematopathology, and pathology exist as medical specialties. Today, pathologists are discovering new diseases, examining exotic diseases that enter the country, and working on a solution to cure diseases such as AIDS, HIV, Herpes, cancer, and more. Thus the evolution of pathology is evidence of the real value of science, which lies in its ability to continually research and develop new methods while giving credit to those who originally developed the idea.^[6]

  Anatomical pathology

  Pathologist instructor and students of anatomical pathology.

Anatomical pathology (Commonwealth) or anatomic pathology (United States) is a medical specialty that is concerned with the diagnosis of disease based on the gross, microscopic, chemical, immunologic and molecular examination of organs, tissues, and whole bodies (autopsy).

Anatomical pathology is itself divided in subspecialties, the main ones being surgical pathology, cytopathology, and forensic pathology. To be licensed to practice pathology, one has to complete medical school and secure a license to practice medicine. An approved residency program and certification (in the United States, the American Board of Pathology or the American Osteopathic Board of Pathology) is usually required to obtain employment or hospital privileges.

Anatomical pathology is one of two branches of pathology, the other being clinical pathology, the diagnosis of disease through the laboratory analysis of bodily fluids and tissues. Often, pathologists practice both anatomical and clinical pathology, a combination known as general pathology. The distinction between anatomic and clinical pathology is increasingly blurred by the introduction of technologies that require new expertise and the need to provide patients and referring physicians with integrated diagnostic reports. Similar specialties exist in veterinary pathology.

  Clinical pathology

  Clinical chemistry: an automated blood chemistry analyser.

Clinical pathology is a medical specialty that is concerned with the diagnosis of disease based on the laboratory analysis of bodily fluids such as blood and urine, and tissues using the tools of chemistry, microbiology, hematology and molecular pathology. Clinical pathologists work in close collaboration with medical technologists, hospital administrations, and referring physicians to ensure the accuracy and optimal utilization of laboratory testing.

Clinical pathology is one of the two major divisions of pathology, the other being anatomical pathology. Often, pathologists practice both anatomical and clinical pathology, a combination sometimes known as general pathology.

  Dermatopathology

Dermatopathology is a subspecialty of anatomic pathology that focuses on the skin as an organ. It is unique in that there are two routes which a physician can use to obtain this specialization. All general pathologists and general dermatologists are trained in the pathology of the skin; however, the dermatopathologist is a specialist in this organ. In the USA, either a general pathologist or a dermatologist can undergo a 1 to 2 year fellowship in the field of dermatopathology. The completion of this fellowship allows one to take a subspecialty board examination, and becomes a board certified dermatopathologist.

  Hematopathology

  Hematopathology: A Wright's stained bone marrow aspirate smear of patient with precursor B-cell acute lymphoblastic leukemia.

Hematopathology is the study of diseases of blood cells (White blood cells, red blood cells, platelets) and cells/tissues/organs comprising the hematopoietic system. The term hematopoietic system refers to tissues and organs that produce and/or primarily host hematopoietic cells and include bone marrow, lymph node, thymus, spleen, and other lymphoid tissues. In the United States, hematopathology is a board certified subspecialty (American Board of Pathology) practiced by those physicians who have completed general pathology residency (anatomic, clinical, or combined) and an additional year of fellowship training in hematology. The hematopathologist reviews biopsies of lymph nodes, bone marrows and other tissues involved by an infiltrate of cells of the hematopoietic system. In addition, the hematopathologist may be in charge of flow cytometric and/or molecular hematopathology studies. After the hematopathologist makes the diagnosis, the hematologist or hemato-oncologist can make a decision about the best course of action.

  Oral and Maxillofacial Pathology

Oral and Maxillofacial Pathology is one of nine dental specialties recognized by the American Dental Association. Oral Pathologists must complete three years of post doctoral training in an accredited program and subsequently obtain Diplomate status from the American Board of Oral and Maxillofacial Pathology. The specialty focuses on the diagnosis, clinical management and investigation of diseases that affect the oral cavity and surrounding maxillofacial structures including but not limited to odontogenic, infectious, epithelial, salivary gland, bone and soft tissue pathologies.

  Forensic pathology

Forensic pathology is a branch of pathology concerned with determining the cause of death by examination of a cadaver. The autopsy is performed by the pathologist at the request of a coroner usually during the investigation of criminal law cases and civil law cases in some jurisdictions. Forensic pathologists are also frequently asked to confirm the identity of a cadaver.

The word forensics is derived from the Latin forēnsis meaning forum.

  Veterinary pathology

Veterinary pathologists are doctors of veterinary medicine who specialize in the diagnosis of diseases through the examination of animal tissue and body fluids. As with medical pathology, veterinary pathology is divided in two branches, anatomical pathology and clinical pathology. Veterinary pathologists are critical participants in the drug development process.

  Plant pathology

  Powdery mildew, a biotrophic fungus

Plant pathology (also phytopathology) is the scientific study of plant diseases caused by pathogens (infectious diseases) and environmental conditions (physiological factors). Organisms that cause infectious disease include fungi, oomycetes, bacteria, viruses, viroids, virus-like organisms, phytoplasmas, protozoa, nematodes and parasitic plants. Not included are insects, mites, vertebrate or other pests that affect plant health by consumption of plant tissues. Plant pathology also involves the study of pathogen identification, disease etiology, disease cycles, economic impact, plant disease epidemiology, plant disease resistance, how plant diseases affect humans and animals, pathosystem genetics, and management of plant diseases.

The "disease triangle" is a central concept of plant pathology.^[7] It is based on the principle that infectious diseases develop, or do not develop, based on three-way interactions between the host, the pathogen, and environmental conditions.

  Molecular pathology

Molecular pathology is an emerging discipline within pathology, and focuses in the study and diagnosis of disease through the examination of molecules within organs, tissues or bodily fluids. Molecular pathology shares some aspects of practice with both anatomic pathology and clinical pathology, molecular biology, biochemistry, proteomics and genetics, and is sometimes considered a "crossover" discipline. It is multi-disciplinary in nature and focuses mainly on the sub-microscopic aspects of disease and unknown illnesses with strange causes.

It is a scientific discipline that encompasses the development of molecular and genetic approaches to the diagnosis and classification of human tumors, the design and validation of predictive biomarkers for treatment response and disease progression, the susceptibility of individuals of different genetic constitution to develop cancer, and the environmental and lifestyle factors implicated in carcinogenesis.^[8]

  Pathology as a medical specialty

Pathologists are doctors who diagnose and characterize disease in living patients by examining biopsies or bodily fluids. In addition, pathologists interpret medical laboratory tests to help prevent illness or monitor a chronic condition.

The vast majority of cancer diagnoses are made by pathologists. Pathologists examine tissue biopsies to determine if they are benign or cancerous. Some pathologists specialize in genetic testing that can, for example, determine the most appropriate treatment for particular types of cancer. In addition, a pathologist analyzes blood samples from a patient's annual physical and alerts their primary care physician to any changes in their health early, when successful treatment is most likely. Pathologists also review results of tests ordered or performed by specialists, such as blood tests ordered by a cardiologist, a biopsy of a skin lesion removed by a dermatologist, or a Pap test performed by a gynecologist, to detect abnormalities.

  This mastectomy specimen contains an infiltrating ductal carcinoma of the breast. A pathologist will use immunohistochemistry and fluorescent in-situ hybridization to detect markers which determine the optimal chemotherapy regimen for this patient.

Pathologists work with other doctors, medical specialty societies, medical laboratory professionals, and health care consumer organizations to set guidelines and standards for medical laboratory testing that help improve a patient's medical care and guide treatment, as well as ensure the quality and safety of domestic and international medical laboratories.

Pathologists may also conduct autopsies to investigate causes of death. Autopsy results can aid living patients by revealing a hereditary disease unknown to a patient's family.

Pathology is a core discipline of medical school and many pathologists are also teachers. As managers of medical laboratories (which include chemistry, microbiology, cytology, the blood bank, etc.), pathologists play an important role in the development of laboratory information systems. Although the medical practice of pathology grew out of the tradition of investigative pathology, most modern pathologists do not perform original research.

Pathology is a unique medical specialty. Pathology touches all of medicine, as diagnosis is the foundation of all patient care. In fact, more than 70 percent of all decisions about diagnosis and treatment, hospital admission, and discharge rest on medical test results.^[9]

Pathologists play a critical role on the patient care team, working with other doctors to treat patients and guide care. To be licensed, candidates must complete medical training, an approved residency program, and be certified by an appropriate body. In the US, certification is by the American Board of Pathology or the American Osteopathic Board of Pathology. The organization of subspecialties within pathology varies between nations, but usually includes anatomic pathology and clinical pathology.

  See also

• Hematopathology
• List of pathologists
• Patho-biotechnology
• Surgical pathology
• Speech-Language Pathology
• Telepathology
• United States and Canadian Academy of Pathology

  References

  External links

• College of American Pathologists
• Pathology Resident Wiki: Complete directory of pathology residency and fellowship training programs.
• Flickr group: Pathology and Lab Medicine: numerous photos illustrating the work of pathologists.
• humpath.com (Atlas in Human Pathology)
• Pathological Society of Great Britain and Ireland
• Royal College of Pathologists (UK)
• Royal College of Pathologists of Australasia (Australia & Oceania)
• United States and Canadian Academy of Pathology
• WebPath: The Internet Pathology Laboratory for Medical Education
• Atlases: High Resolution Pathology Images
• pathologybook.info the most comprehensive book information of pathology-related
• pushglass: pathology image search