Anatomical pathology

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Anatomical pathology is the branch of pathology that is concerned with the diagnosis of disease based on the gross and microscopic examination of cells and tissues. The father of the modern Anatomical pathology is the Italian Giovanni Battista Morgagni.

Anatomical Pathology (AP) is one of the two primary certifications offered by the American Board of Pathology. The other is Clinical Pathology (CP).

1 Role of the anatomical pathologist
2 Procedures
3 Subspecialties
4 See also
5 External links

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Role of the anatomical pathologist

Contrary to popular belief, the field mostly concerns the study of tissue obtained from live patients. In fact, almost all tissues removed from a patient for any reason are examined by a pathologist. The autopsy, though, remains an important tool in gaining medical knowledge.

Biopsy specimens are small pieces of tissue taken from a tumor when its nature is uncertain. Histological examination of the biopsy usually allows the pathologist to determine if the tumor is benign or malignant, and differentiate between different types of cancer. This information is important for accurate estimation of the prognosis and choice of the best therapy. Biopsies can also be used to diagnose diseases other than cancer. For example, the dermatopathologist sees many skin biopsies from rashes and other inflammatory skin diseases, taken by dermatologists when the nature of the disease is not evident. Stomach and colon biopsies are also taken to help diagnose inflammatory or infectious diseases of the digestive tract.

In contrast to a biopsy that merely samples a lesion, an excision (or resection) specimen is the complete removal of the tumor or diseased organ by a surgeon. For example, a mastectomy specimen contains the whole breast tissue, overlying skin and adjacent lymph nodes. On excision specimens, the pathologist will comment on surgical margins to estimate the likelihood that the tumor was completely excised during the surgery.

The opinion of the pathologist is written as a pathology report addressed to the doctor who performed the procedure.

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Procedures

The procedures used in anatomical pathology include:

Gross pathology, 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 the part that will be processed for histopathology.
Histopathology is the Microscopic examination of stained tissue sections using histological techniques. The standard stains are haematoxylin and eosin but many others exist. The science of staining tissues sections is called histochemistry. Antibodies can also be used to stain specific proteins, a technique called immunohistochemistry. Specific DNA and RNA molecules can be identified on sections using the technique of in situ hybridization. When the probe is labeled with fluorescent dye, the technique is called FISH.
Cytopathology is the examination of loose cells spread and stained on glass slides using cytology techniques.
Electron microscopy is used to identify organelles within the cells. Its usefulness has been greatly reduced by immunhistochemistry but it is still irreplaceable for the diagnosis of kidney disease, identification of immotile cilia syndrome and many other tasks.
Tissue cytogenetics can identify genetics defects, like chromosomal translocation.
Flow immunophenotyping is the determination of the immunophenotype of cells using flow cytometry techniques. It is very useful to diagnose the different types of leukemia and lymphoma.

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Subspecialties

Doctors turn to pathologists for help when the diagnosis is not evident. Therefore, pathologists are expected to know many more diseases than clinicians - they are the "doctor's doctor". The amount of knowledge needed is enormous. Since one person cannot possibly know everything, pathologists tend to sub-specialize. The American Board of Pathology certifies anatomical pathologists, and recognizes the following secondary specialties of Anatomic Pathology: Neuropathology, Cytopathology, Dermatopathology, Forensic pathology, Hematology. Here is a (probably incomplete) list of the commonly recognized subspecialties, including those which do not have subspecialty boards:

Surgical pathology: diagnosis of diseases in organs removed by general surgeons, especially breast, lung, bowel. This is the core of anatomical pathology. Most of these organs are covered by sub-subspecialties:
- Gastrointestinal pathology: diagnosis of bowel diseases from biopsies taken by a gastroenterologist. One of its sub-subspecialty is hepatopathology, the diagnosis of liver diseases based on liver biopsy.
- Uropathology, including diseases of the urinary tract and the male genital tract
- Cardiac pathology
- Pulmonary pathology
- Endocrine pathology
- Gynecologic Pathology, including diseases of the female genital tract and the placenta
- soft tissue pathology and orthopedic pathology
- E.N.T. Pathology
- Neuropathology: diagnosis of diseases from tissues removed by neurosurgeons. Neuropathologists also examine whole brains and spinal cords removed at autopsy.
- Dermatopathology: diagnosis of skin diseases from the histological examination of skin biopsies taken by a dermatologist.
- Ophthalmic pathology
- Hematopathology
- Nephropathology
- Pediatric pathology and its sub-subspecialty neonatal pathology
- Immunopathology
Cytopathology
Forensic pathology

Oral & Maxillofacial pathology is different; the American Board of Oral and maxillofacial pathology certifies dentistry doctors, not medical doctors, to practice this sub-specialty of Pathology.

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