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[[Image:Renal Cell Carcinoma.jpg|thumb|right|200px|A renal cell [[carcinoma]] (chromophobe type) viewed on a [[hematoxylin]] & [[eosin]] stained slide]]

In [[medicine]], '''pathology''' is the study and [[medical diagnosis|diagnosis]] of [[disease]]. The related [[science|scientific]] study of disease processes is called "[[general pathology]]". Medical pathology is divided into two main branches, [[anatomical pathology]] and [[clinical pathology]]. Medical pathologists work through examination of [[Organ (anatomy)|organs]], [[tissue (biology)|tissues]], [[bodily fluid]]s, and whole bodies ([[autopsies]]). 

The term "pathology" has a broader meaning in the sciences to refer to the study of disease, not specifically in the domain of biology. For example in [[psychology]], the term "[[psychopathology]]", or simply "pathology," considers paths within its domain ([[mental disorder|mental]], [[Emotional and behavioral disorders|emotional and behavioral]]) to be forms of "illness" or "disease."

[[Veterinary pathology]] is concerned with animal disease, whereas [[phytopathology]] is the study of plant diseases.

The word ''[[wiktionary:pathology|pathology]]'' is from [[Ancient Greek|Greek]] {{lang|grc|πάθος}}, ''pathos'', "feeling, suffering"; and {{lang|grc|-λογία}}, ''[[wiktionary:-logia|-logia]]''. ''[[Pathologization]]'', to pathologize, refers to the process of defining a condition or behavior as pathological.

==General pathology==
{{Main|General pathology}}
General pathology, also called investigative pathology, experimental pathology, or theoretical pathology,{{Citation needed|date=July 2009}} is a broad and complex [[science|scientific field]] which seeks to understand the mechanisms of injury to [[Cell (biology)|cells]] and [[tissue (biology)|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.

===Anatomical pathology===
{{Main|Anatomical pathology}}
[[File:UNDmicroscope.jpg|thumb|200px|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 examination|gross]], [[Histopathology|microscopic]], chemical, immunologic and [[Molecular pathology|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 [[Medical license|licensed]] to practice pathology, one has to complete [[medical school]] and secure a license to practice medicine.  An approved [[Residency (medicine)|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 [[Medical laboratory|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===
{{Main|Clinical pathology}}
[[Image:Konelab60i.png|thumb|200px|right|[[Clinical chemistry]]: an automated blood chemistry analyser.]]Clinical pathology is a medical specialty that is concerned with the diagnosis of disease based on the [[Medical laboratory|laboratory]] analysis of bodily fluids such as blood and [[urine]], and tissues using the tools of [[clinical chemistry|chemistry]], [[Clinical microbiology|microbiology]], [[hematology]] and molecular pathology.  Clinical pathologists work in close collaboration with [[medical technologist]]s 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 dermatpathologist.

==Forensic pathology==
[[File:Birth defect03.jpg|thumb|200px|Birth defect]]
{{Main|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 (common law)|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==
{{Main|Veterinary pathology}}
Veterinary pathologists are [[veterinarians|doctors of veterinary medicine]] who specialize in the [[medical diagnosis|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.

== Psychopathology ==
In [[psychology]] and [[psychiatry]], '''psychopathology''' is the study of mental illness, mental distress and abnormal, maladaptive behavior. The term is most commonly used within psychiatry where pathology refers to disease processes. Abnormal psychology is a similar term used more frequently in the non-medical field of psychology. 

==Plant pathology==
{{Main|Phytopathology}}
[[File:Powdery mildew.JPG|thumb|[[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.<ref name=Arios>George N. Agrios (1997) Plant Pathology fourth edition, Academic Press. New York.</ref> 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==

{{see|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.<ref>http://www.molecularpathology.org.uk/</ref>

== Pathology as a medical specialty ==
{{Main|Pathology as a medical specialty}}

{{Infobox Occupation
| name= Pathologist
| image= 
| caption= 
| official_names= Doctor, Medical Specialist  
<!------------Details------------------->
| type= [[Specialty (medicine)|Specialty]]
| activity_sector= [[Medicine]]
| competencies= 
| formation= Degree in Medicine
| employment_field= [[Hospital]]s, [[Clinic]]s
| related_occupation= 
| average_salary= {{profit}} USD $242,000
}}

Pathologists are doctors who diagnose and characterize disease in living patients by examining [[Biopsy|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.   

[[Image:Infiltrating ductal carcinoma of the breast.jpg|thumb|right|200px|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 laboratory|medical laboratories]] (which include chemistry, microbiology, cytology, the blood bank, etc.), pathologists play an important role in the development of [[laboratory information system]]s. 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.

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==
* [[Surgical pathology]]
* [[Hematopathology]]
* [[Telepathology]]
* [[List of publications in biology#Pathology|Important publications in pathology]]
* [[List of pathologists]]

==References==
{{reflist}}

==External links==
* [http://www.cap.org/ College of American Pathologists]
* [http://www.flickr.com/groups/labmed/ Flickr group: Pathology and Lab Medicine]: numerous photos illustrating the work of pathologists. 
* [http://www.humpath.com/ humpath.com] (Atlas in Human Pathology)
* [http://www.pathsoc.org.uk/ Pathological Society of Great Britain and Ireland]
* [http://www.rcpath.org/ Royal College of Pathologists (UK)]
* [http://www.rcpa.edu.au Royal College of Pathologists of Australasia (Australia & Oceania)]
* [http://www.uscap.org/ United States and Canadian Academy of Pathology]
* [http://library.med.utah.edu/WebPath/webpath.html WebPath: The Internet Pathology Laboratory for Medical Education]

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