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Pathology is a medical specialty that provides the scientific foundation for all medical practice. The pathologist works with all other medical specialties, using the tools of laboratory medicine (histology, cytology, biochemistry, molecular biology, etc.) to provide information essential to problem solving in clinical practice. 

Because of its broad and heterogeneous nature, the field of pathology allows one to select a niche which suits his or her specific desires and needs; whether it be strictly in community or in private clinical practice, or in academic medicine, with components of research and/or teaching, anatomic or clinical pathology or a combination thereof - pathology has the flexibility to accommodate most individuals.   It also has an appeal for those seeking flexibility in life-style choices, especially for those wishing to have time for family.  Many pathologists are generalists concerned with all facets of disease that are analyzed in the laboratory. Others specialize and interact with clinical sub-specialists. Wherever and  whatever they practice, their findings are fundamental to medical diagnosis, patient management and research.

The pathologist's role in medical practice is diverse. They can serve as:

  • consultants to the physician
  • consultants to the patient
  • directors of laboratories 
  • leaders in administration
  • researchers, or
  • educators

As consultant physicians, they can be considered the "doctor's doctor".  Pathologists participate in day-to-day care of hospital patients by providing and interpreting laboratory information to help solve diagnostic problems and to monitor the effects of therapy.  They are required to provide fast and accurate consultation, applying their knowledge to assist in the diagnosis and treatment of individual patients.  With new and highly complex tests increasing in recent years, clinicians rely more and more on the pathologist for guidance and direction in use of the clinical laboratory.  While the responsibility of the pathologist may be less direct than that of other physicians, it is no less than that of other physicians.  In fact, the pathologist holds a central position in patient care, since their diagnoses form the underpinning for future therapy.  Pathologists are not simply "laboratory physicians"; they can have more contact with patients than would be first imagined.  They provide consultations with clinical colleagues, such as surgeons, radiologists, and even primary care physicians, which means that they can be frequently found "on the ward floor" or in the operating room, on consultations and seeing patients.  They can occasionally, at the behest of the clinician, also engage in providing information directly to the patient or family of the patient. 

Pathologists often oversee the functioning of the various laboratories that process patient samples. In this capacity, they supervise a team of technologists and technicians. They are also responsible for development and institution of appropriate quality control and quality assurance programs that ensure efficient, economical, yet high quality of medical care. 

Because of the broad perspective that pathologists assume in the field of medicine, they are often called upon to serve in various administrative capacities, especially in situations requiring the drawing together of the different disciplines of medicine.  Pathologists often serve as deans and as members of institutional, state, regional and national professional and research bodies.

Pathologists are also uniquely positioned in the field of medicine to be leaders in basic research; they have a familiarity with clinical medicine, they have insight into the significance of diseased tissue changes, they have direct access to patient specimens, and they are familiar with laboratory technologies. Pathology has a special appeal to those who enjoy solving disease-related problems, using technology based upon fundamental biologic sciences, such as biophysics and molecular genetics. As medical scientists, they make contributions that advance the understanding of disease processes as a first step toward devising better ways to identifying, controlling and preventing disease. 

As teachers, pathologists impart their knowledge of disease to their medical colleagues via consultations and formal seminars, and to house-staff and to medical and undergraduate students. 

The Divisions of Pathology

The discipline of pathology is divided into three major areas:

  • Anatomic Pathology
  • Clinical Pathology
  • Experimental Pathology

Anatomic Pathology

Anatomic pathologists analyze the gross and microscopic structural changes caused by disease in tissues or cellular fluids removed during surgery or at autopsy.  The following sub-divisions of anatomic pathology are generally recognized:

  • Surgical Pathology
    • gross appearance and histology of tissues removed during surgery
  • Cytopathology
    • single cells, smears, aspirates and body fluids
  • Autopsy
    • gross appearance and histology of tissues removed following death
    • specialized laboratory testing, forensic pathology

There are a number of sub-specialties of anatomic pathology, including forensics, oral pathology, neuropathology, dermatopathology, and others, in which a pathologist may specialize and receive medical board credentialing.

Clinical Pathology

In the clinical laboratory, the pathologist uses diagnostic and screening tests to identify and interpret changes that characterize different diseases or disease states in cells, tissues, and fluids of the body. They also monitor the metabolic status of patients under medical therapy and decipher specific markers that characterize individual patients for purposes such as transfusion or transplantation. The following sub-divisions are generally recognized:

  • Hematopathology
    • blood, bone marrow, coagulation
  • Transfusion Medicine (Blood Banking)
  • Clinical Chemistry
    • electrolytes, metabolites, proteins, hormones
    • toxicology and therapeutic drug monitoring
  • Microbiology
    • viruses, bacteria, fungi, etc.
  • Cytogenetics
  • HLA Laboratory
  • Molecular Diagnostics

Certain sub-specialties of pathology, such as molecular pathology and medical informatics, do not fit neatly into either of the main categories (anatomic or clinical) but rather straddle these disciplines. 

The majority of pathologists study both clinical and anatomic pathology during their house-staff training, and become board-certified in both disciplines; however, ultimately, most specialize in either one or the other field. 

The Anatomic Pathologist

Tissue in paraffin block and unstained and stained slides

Surgical specimen is "grossed-in" by a pathology resident

The Surgical Pathologist is responsible for diagnosing all tissues removed from the patient during surgery and at autopsy.  Tissues are either sliced frozen or embedded in paraffin wax and sliced, then the very thin sections of the tissue are mounted on glass slides and stained in various ways to permit examination of the histology and special components of the tissue.  Changes in the histology or composition of the tissue aid the pathologist in making a diagnosis. To sharpen the precision of diagnoses, pathologists apply sophisticated new techniques involving monoclonal antibodies, molecular biology, image analysis, electron microscopy, and flow cytometry to the patient's specimens. Each diagnosis is made in collaboration with the patient's physician after consideration of the clinical history and the results of other laboratory tests.

The Cytopathologist, studies individual cells in smears, aspirates, and body fluids, such as pleural, peritoneal, and cereobrospinal fluids, and urine, to detect disease. Cytopathology, is assuming an increasing importance in modern patient care. Originally dominated by the Papapanicolaou or "Pap" smear (see image left) in the detection of female uterine cervical cancer, cytopathology principles are now being applied to all organ systems and their diseases. A specialized form of cytopathology is fine needle aspiration biopsy.  Pathologists often see patients for examination of the lesion and perform the procedure themselves.  Direct feedback to the clinician based on clinical and microscopic features is a unique a particularly rewarding area.  Pathology has its own FNA clinic space within the new outpatient facility(Case Study 1).  

The Autopsy provides unique insights into the natural history of disease and the influence of therapy on disease processes. After an autopsy, the pathologist discusses the findings with the patient's physician and often with other physicians in hospital conferences. Together, they evaluate the findings in each case so that future patients may benefit from this information. Autopsy data are used extensively as a quality-control measure. Current studies show a consistent 30 percent discrepancy rate between clinical diagnoses and actual findings at autopsy.  One of the frequent comments made by pathologists is the gratification that they receive as being the ones who make the final consult - the clinician may make an educated "guess" at the diagnosis from examination of the patient but the final definitive diagnosis generally lies with the pathologist.

The autopsy's value is dramatized when the pathologist is called to determine the exact cause of death in legal cases and to present the findings as an officer of the court. Pathologists who are specially trained and certified in forensic pathology serve as medical examiners for states and large cities. They conduct postmortem studies of suspicious deaths and work intimately with local and state law enforcement officers.

The Clinical Pathologist

The Clinical Pathologist is responsible for the clinical laboratories which cover hematology, clinical chemistry (including toxicology), microbiology (including immunology), and the blood bank (transfusion medicine). These activities involve the pathologist in patient care as a consultant. Some areas of the Clinical Pathology laboratory are also often overseen by Ph.D.s, trained to supervise these specialty clinical labs.  Various programs around the nation offer post-doctoral training leading to board certification in clinical chemistry (e.g., through the American Association of Clinical Chemistry), medical genetics, cytogenetics, microbiology, virology, etc.

In the clinical hematology laboratory, pathologists review all abnormal blood smears. They may also obtain bone marrow specimens from patients. By examining the smear and histological sections of marrow, the pathologist can provide definitive diagnoses of diseases such as leukemia. The pathologist also serves as consultant on special hematologic problems, such as those related to bleeding disorders.

Functioning as an immunohematologist, the pathologist in most hospital settings is in charge of the blood bank, with responsibility for procurement and processing of blood and blood products. The pathologist monitors the use of blood within the hospital, traces the causes of any transfusion reactions, and serves as a consultant in planning appropriate therapy.

In clinical chemistry, the pathologist supervises the technical staff in performance of tests, use of instruments and maintenance of a strict system of quality control. Toxicology is often part of the clinical chemistry service, involving the pathologist in therapeutic drug monitoring and detection of illicit drugs and poisons.  Pathologists have spearheaded the new field of molecular diagnostics, becoming the first to bring DNA molecular biology directly to the bedside. Now pathologists can identify carriers of genetic disease, diagnose viral and bacterial infections and monitor cancer therapy using DNA technology. Genetic susceptibility to inherited cancer is a dynamic new testing area.  In addition to traditional testing for immune responses to various agents of disease by immunology, the pathologist uses the tools of molecular biology to help assess the ability of patients to protect themselves from various environmental factors and to tolerate a transplanted organ. In forensics, pathologists perform DNA fingerprinting for identification. 

Abnormal results are identified on the laboratory reports, and the pathologist communicates with the patient's physician when there are unusual or unexpected results that requires follow-up. This is of special concern when life-threatening critical values are found, requiring immediate response.

Pathologists play a major role in the development and appropriate utilization of comprehensive information systems, ensuring economical use of the clinical laboratory while maintaining, a high quality of medical care.

The Pathologist As Teacher

One of the great appeals of a pathology career is the opportunity to teach. No other medical specialty offers as many different opportunities in education.  Pathologists teach at the bedside, in the laboratory, over the microscope, in the lecture hall, in the classroom, in workshops and in seminars. They instruct medical students, residents in pathology and other clinical services, graduate students in basic science departments, and students in medical technology and nursing education programs.

Pathologists are closely involved in the continuing medical education of' practicing physicians. In community hospitals where the pathology laboratory performs tests on entering patients, the pathologist has a broad view of all patient problems. Other specialists call on them for formal teaching conferences and for consultation on individual patients as well as for guidance on the application and usefulness of newly available tests.  Pathologists also play a major role in the conferences held by the clinical services of all hospitals, large and small. 

In medical school, pathology is a required basic science, and additional pathology courses can be taken as electives. In many schools, medical students with high ranking in their pathology course are named to the Pathology Honor Society, a national honorary society sponsored by the Association of Pathology Chairs.  As an indication of our commitment and dedication to teaching at the University of Oklahoma Health Sciences Center, the Sophomore Medical School Class Aesculapian Award for Outstanding Teacher of the Year has been presented to a member of the Pathology Department every year for the past 12 years, and since 1988 there have been 28 nominees from the department for this award.

Pathologists are committed to their own educational growth and regularly attend programs at local, regional and national meetings, where diagnostic applications of new basic science findings and technology are presented.

The Research Pathologist

Pathology is attractive to those who like to be on the cutting edge and who are not only content merely to treat disease but who are compelled to search for and find solutions.  Pathologists are often referred to as "medical detectives", since they are always in search of definitive answers.  The pathologist-investigator seeks new understanding of the basic nature of disease as a first step toward devising better ways to identify, control and prevent it.  Pathologists have a unique advantage in biomedical research because of their close ties to clinical medicine, their familiarity with laboratory technology, and their insight into the significance of diseased tissue changes.

In this quest for answers, usually thenormalmust be unraveled and understood before we can appreciate theabnormal. And because it is frequently a defect in the normal processes that leads to disease, normal biological functions must be understood at a molecular level.  Pathologists engaged in research use the sophisticated technologies of modern molecular biology, biochemistry, immunology, cell biology and tissue pathology. These tools and methods include cell culture, biochemical analysis, electron microscopy, immunological and molecular genetic techniques, computer modeling, and use of animal models.

The range of problems under study by research pathologists spans all disease processes and may involve tracing a newly recognized disease to its origin. Experimental pathologists use the power of molecular biology to identify the genes involved in many disease processes, ranging from cancer to inherited diseases and infections.  The pathologist plays a key role in improving diagnoses through identifying new pathogenic bacteria, discovery of new infectious agents, and better application of modern methods of diagnosis such as magnetic resonance imaging (MRI). Examples are the unraveling of the role of retroviruses in AIDS and the utility of MRI in diagnosing multiple sclerosis.

Nobel Prize winners have included pathologists who used their understanding of pathologic processes to make significant contributions to medicine. Nobel Laureate pathologists have included Karl Landsteiner, George Whipple, Howard Florey, Alexander Fleming, MacFarlane Burnet and Baruj Benacerraf. 

Career Options in Pathology

In a community hospital practice, the pathologist plays a role in the clinical decision making of physicians in all medical specialties on the hospital staff. As laboratory director, the pathologist is involved in quality improvement, risk management, continuing medical education, and development of comprehensive information systems. Hospital pathologists often operate laboratories that also serve the office practices of their community's physicians.  Although 75 percent of pathologists practice in the community hospital setting, many other options exist.

Medical schools attract the second largest group of pathologists - about 3,000 - often those who desire extensive teaching opportunities, and time for basic or applied research. Pathologists often serve as deans and as members of national professional and research bodies.

With the growth of ambulatory care, pathologists may also practice innon-hospital settings, such as private or group practice, clinics, and other health care facilities.

Independent laboratories have assumed an increasing role as practice sites for pathologists. Many of these laboratories are part of major national medical networks; others are regional or local.

Forensic pathologists typically work in municipal, state and federal agencies, where they investigate unexplained and unnatural deaths.

Positions for pathologists are also available in the military and in government agencies, such as the National Institutes of Health, Armed Forces Institute of Pathology, and Food and Drug Administration.

In addition, pathologists often assume leadership positions in research institutes and with pharmaceutical and biotechnology companies.

The best available data suggest a continuing need for pathologists in all sectors in the future.

Training to become a Pathologist

Medical school graduates need four to five years of accredited residency training to prepare for a career in pathology. Accredited training programs in many hospitals throughout the United States and Canada offer this training and opportunities for subspecialty study. During training, the resident becomes familiar with all activities of a pathology department.

Most pathology residents train in both anatomic pathology (AP) and clinical pathology (CP), although it is possible to train in only one. Specialty certification for the medical practice of pathology is the responsibility of the American Board of Pathology (ABP) which offers primary specialty and subspecialty examinations for certification. Four full years of approved pathology training are required for AP/CP, and three years for only AP or CP. All applicants are then required to have one additional full year of clinical training, and/or clinically related research, or an additional year of advanced pathology training in AP or CP or combination thereof.  For more information on residency training contact the ABP (address below) and visit our Residency Program page.

Following this training, candidates requesting certification must pass an objective written and practical examination. As in other medical disciplines, Board certification is not required for practice, but it is highly prized as evidence of professional competence.

The ABP also offers examinations to certify expertise in 10 subspecialty areas of anatomic and clinical pathology:

  • blood banking /transfusion medicine
  • chemical pathology
  • cytopathology
  • forensic pathology
  • hematology
  • immunopathology
  • medical microbiology
  • neuropathology
  • pediatric pathology
  • dermatopathology (American Board of Dermatology)
  • molecular pathology (as of year 2001)

In the United States-theAmerican Board of Pathology, P.O. Box 25915, Tampa, Fl, 33622-5915, (813)286-2444, publishes a Booklet of Information on Board certification and requirements. In Canada, write to the Office of Training and Evaluation, Royal College of Physicians and Surgeons, 74 Stanley Ave., Ottawa K1M, 1P4, for information on certification.

Additional Sources of Information

Pathology as a Career

Contact with individual pathologists in hospitals, laboratories and medical schools is the best way to learn about the profession and its personal rewards. For additional information about pathology as a career, contact local, state or national pathology organizations.

Undergraduate Study in Pathology

Medical schools offer elective courses in pathology in addition to the required basic science courses. Some medical schools offer "year-out" student fellowships in pathology for medical students usually following the sophomore year. Under certain circumstances, candidates for primary certification by the American Board of Pathology may receive advanced pathology training credit for this period. See our Graduate Program in pathology at the University of Oklahoma Health Sciences Center.

Residency Training

Directory of Pathology Training Programs is published annually in June by theIntersociety Committee on Pathology Information (ICPI). It contains detailed information about accredited residency and postgraduate subspecialty fellowship programs in the United States and Canada. Also listed are medical school post-sophomore fellowships in pathology. Copies of the Directory are sent to all U.S. and Canadian medical schools, medical libraries and teaching hospitals, or may be obtained from ICPI, 4733 Bethesda Avenue, Suite 700, Bethesda, MD 20814; telephone (301)656-2942.

The American Medical Association's annual source book, lists all programs accredited by the Accreditation Council for Graduate Medical Education. Reference copies are located in medical schools and medical libraries or can be purchased from the AMA, 515 North State Street, Chicago, IL 60610; telephone (312)464-4635.

See our Residency Programin pathology at the University of Oklahoma Health Sciences Center.