Anatomical pathology (or Anatomic pathology) is a medical specialty that is concerned with the gross, microscopic, chemical, immunologic, and molecular examination of organs, tissues, and whole bodies (as in autopsy) to determine the presence of disease. Italian scientist Giovanni Battista Morgagni is widely considered the founding father of anatomic pathology.
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. 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.
Differences between anatomic pathology and clinical pathology
Anatomic pathology relates to the processing of surgical and gynecological specimens. Its sub-specialties include surgical pathology (neuropathology, dermatopathology, etc.), cytopathology, and forensic pathology.
Clinical pathology is the division that processes the test requests more familiar to the general public; such as blood cell counts, coagulation studies, urinalysis, blood glucose level determinations, and throat cultures. It typically encompasses chemistry, hematology, microbiology, immunology, urinalysis, and blood bank.
The differences between the two may appear to be small, but the differentiation in laboratory workflow of these two medical specialties has led to the creation of different functionalities in the laboratory information systems (LISs) and anatomic pathology computer systems often utilized while practicing these specialties. Specimen collection, receipt, and tracking; work distribution; and report generation may vary — sometimes significantly — between the two types of labs, requiring targeted functionality in the utilized software. Other differences include:
- Specific dictionary-driven tests are found in clinical pathology environments but not so much in anatomic pathology environments.
- Ordered anatomic pathology tests typically require more information than clinical pathology tests.
- A single anatomic pathology order may be comprised of several tissues from several organs; clinical pathology orders usually do not.
- Anatomic pathology specimen collection may be a very procedural, multi-step processes, while clinical pathology specimen collection is routinely more simple.
Skills and procedures
The procedures used in anatomic pathology include:
- Gross examination – the examination of diseased tissues with the naked eye. This is important especially for large tissue fragments, because the disease can often be visually identified. It is also at this step that the pathologist selects areas that will be processed for histopathology. The eye can sometimes be aided with a magnifying glass or a stereo microscope, especially when examining parasitic organisms.
- Histopathology – the microscopic examination of stained tissue sections using histological techniques. The standard stains are haematoxylin and eosin, but many others exist. The use of haematoxylin and eosin-stained slides to provide specific diagnoses based on morphology is considered to be the core skill of anatomic pathology. The science of staining tissues sections is called histochemistry.
- Immunohistochemistry – the use of antibodies to detect the presence, abundance, and localization of specific proteins. This technique is critical to distinguishing between disorders with similar morphology, as well as characterizing the molecular properties of certain cancers.
- In situ hybridization – Specific DNA and RNA molecules can be identified on sections using this technique. When the probe is labeled with fluorescent dye, the technique is called fluorescent in situ hybridization (FISH).
- Cytopathology – the examination of loose cells spread and stained on glass slides using cytology techniques.
- Electron microscopy – the examination of tissue with an electron microscope, which allows much greater magnification, enabling the visualization of organelles within the cells. Its use has been largely supplanted by immunohistochemistry, but it is still in common use for certain tasks, including the diagnosis of kidney disease and the identification of immotile cilia syndrome among many others.
- Tissue cytogenetics – the visualization of chromosomes to identify genetics defects such as chromosomal translocation.
- Flow immunophenotyping – the determination of the immunophenotype of cells using flow cytometry techniques. It is very useful to diagnose the different types of leukemia and lymphoma.