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.
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
Nobel Prize winners have included pathologists who used their understanding of pathologic processes to make significant contributions to medicine. Some of the Nobel Laureate pathologists have included: Karl Landsteiner, George Whipple, Howard Florey, Alexander Fleming, MacFarlane Burnet and Baruj Benacerraf.
As consultant to the physicians, 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. They provide consultations with clinical colleagues, such as surgeons, radiologists, and even primary care physicians. 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
- General Pathology
Anatomic pathologists analyse 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:
- Anatomical Pathology
- gross appearance and histology of tissues removed during surgery
- single cells, smears, aspirates and body fluids
- Autopsy/ Forensic
- 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, dermato-pathology, and others, in which a pathologist may specialize and receive medical board credentialing.
The Anatomic Pathologist/ Histo- 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.
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:
- blood, bone marrow, coagulation
- Transfusion Medicine (Blood Banking)
- Clinical Chemistry
- electrolytes, metabolites, proteins, hormones
- toxicology and therapeutic drug monitoring
- Viruses, bacteria, fungi, etc.
- 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 Clinical Pathologist is responsible for the clinical laboratories which cover haematology, 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.
In the clinical haematology 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 leukaemia. The pathologist also serves as consultant on special hematologic problems, such as those related to bleeding disorders.
Functioning as an immuno-haematologist, 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.
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 a 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.
In medical school, pathology is a required basic science, and additional pathology courses can be taken as electives. 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 the normal must be unraveled and understood before we can appreciate the abnormal. 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.
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.