Histopathology Report - How is it Done and What Does it Include?

Histopathology Report Techniques and Prognostic Predictors

Histopathology involves scrutinizing tissue samples to identify a particular disease.

Histopathology is the examination of tissues from the body under a microscope to spot the signs and characteristics of disease. Histology is the study of tissues, and pathology is the study of disease.

So taken together histopathology literally means the study of tissues as relates to disease. A histopathology report describes the tissue that has been sent for examination and the features of what the cancer looks like under the microscope.

A histopathology report is sometimes called a biopsy report or a pathology report.

The Histopathology Report

The specialist doctor who does the examination under the microscope is called a Pathologist. The tissue that is studied comes from a biopsy or surgical procedure whereby a sample of the suspect tissue is selected and sent to the laboratory. It is then processed and cut into very thin layers (called sections), stained and examined under microscopes to characterize the details of the cells in the tissue. For some diseases, the surgeon can get a sample of the tissue interpreted very quickly through the use of frozen sections. Frozen sections or slices are used sparingly in lymphoma, however, due to problems in interpretation and sampling. In lymphomas, lymph nodes are the tissue most commonly examined in histopathology. For many types of blood cancers, a bone marrow biopsy may also be required for a definitive diagnosis.

Components of the Report

Histopathology reports on surgical cancer specimens are getting more and more complex. They may include:

  • The microscopic appearance of the involved tissue
  • Special stains
  • Molecular techniques
  • Other tests

Molecular techniques refer to the ability to analyze cells and tissues at the molecular level, which is at the level of proteins, receptors, and the genes that code for these things.

Interpreting the Report

Many of the findings from such examination of the tissues are linked to prognosis. Prognostic indicators may include tumor grade and extent of spread, and whether or not the cancer was removed with a margin of healthy cells surrounding it, or if there is evidence the cancer has spread beyond what was removed.

Grading systems differ depending on the kind of cancer being graded, but generally the cells are scored based on how abnormal they appear under the microscope, with Grade 1 tumors being more normal looking and Grade 4 tumors reflecting more abnormalities. A high-grade tumor, then, is generally one in which the cells have more abnormalities. Grading is not the same as staging. Staging has more to do with where the cancer is found in the body and how far it has spread.

Molecular Descriptions and Other Sampling Techniques

In addition to the histopathology, other techniques may be used to assess the presence of cancer in the tissues, including fine needle aspiration cytology, and some of these techniques may be used more extensively in health care settings around the world.

Often times in lymphomas and other cancers, something called immunohistochemistry is done to help assess the tumor type, prognosis and treatment.

For instance, the presence of the following markers may be investigated for lymphoma:
CLA (CD 45), L26 (CD20), CD 3, UCHL1 (CD45R0), kappa/lamda light chain restriction, CD 15, CD 30, bcl-2/bcvl-1, CD 5, CD 10, tdt.

For a given sample, markers can be tested using a whole panel of antibodies, with positive and negative controls, built in.

Molecular and chromosomal studies may be done to look at gene rearrangements and specific changes to the chromosomes.

Sometimes inserted or deleted genes are linked to information about prognosis. For instance, in chronic lymphocytic leukemia, or CLL, a specific piece of a chromosome is lost, and often times lost along with it is a gene that helps supress cancer. The 17p deletion is found in about 3 to 10 percent of people with CLL, overall. 17p deletion CLL is a form of CLL that is harder to treat; people with 17p deletion CLL tend to be difficult to treat with conventional chemotherapy.

Sources:

Ho C, Rodig SJ. Immunohistochemical markers in lymphoid malignancies: Protein correlates of molecular alterations. Seminars in Diagnostic Pathology. 2015. 32(5):381-91.

Histopathology Reporting: Guidelines for Surgical Cancer. By Derek C Allen. Springer Science & Business Media, Jun 29, 2013.

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