What Is Histopathology?

Histology is the study of tissues, and pathology is the study of disease. So taken together, histopathology means the study of tissues related to disease.

A histopathology report describes the tissue that the pathologist examined. It also identifies features of what cancer looks like under the microscope. A histopathology report is also called a biopsy report or a pathology report.

This article explains what is in a histopathology report and how to interpret results.

How Is Histopathology Performed?

A specialist doctor who examines tissue under a microscope is called a pathologist. Pathologists study biopsied tissue in a lab.

Pathologists process and cut tissue into very thin layers (called sections). Then, they stain and examine it under a microscope. Under a microscope, they can observe and document the tissue's cell details.

Frozen Section

For some diseases, the surgeon can get a sample of the tissue interpreted very quickly through frozen sections (also called a cryosection). Frozen sections are emergency procedures in the lab and usually require a result within about 20 minutes.

This type of pathology is most commonly used to evaluate tumor margins to determine if a surgeon needs to remove more tissue.

However, frozen sections or slices are used sparingly in lymphoma due to problems in interpretation and sampling.

Lymph and Blood Cancers

Lymph nodes are the tissue most commonly examined to evaluate lymphomas in histopathology. A bone marrow biopsy may also be required for a definitive diagnosis for many types of blood cancers.​

Components of a Histopathology Report

Histopathology reports on surgical cancer specimens can be complex. They may include:

• The appearance of the involved tissue
• Diagnosis
• Synoptic report detailing the findings of the case
• Pathologist's comments

Interpreting the Results

Many of the pathologist's findings inform prognosis.

Prognostic indicators may include:

• Tumor grade
• Extent of spread
• Evidence of healthy cells around the cancer
• Evidence cancer has spread

Grading systems differ depending on the kind of cancer. However, the cells are generally scored based on how abnormal they appear under the microscope.

For example, Grade 1 tumors appear more normal, whereas Grade 4 tumors reflect more abnormalities. In other words, the higher the grade, the higher the abnormalities.

Other Sampling Techniques

In addition to histopathology, pathologists may use other techniques to assess the presence of cancer in the tissues.

Molecular Techniques

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

Pathologists diagnose leukemias and lymphomas through a combination of techniques, including:

• Cytochemistry: How cells in the bone marrow take up certain stains
• Immunophenotype: Looks for unique surface proteins
• Karyotype: Chromosomal changes
• Morphology: How the cells look

Immunohistochemistry

Often in lymphomas and other cancers, doctors use immunohistochemistry to help assess the tumor type, prognosis, and treatment.

For example, if CD23 and CD5 are present in the cancer cells, it might support the notion that chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL) is a possible diagnosis.

However, these same markers are also present in other malignancies. So doctors use a process of elimination based on the available information and what is known about the various malignancies and their "typical" CD markers.

Another example of a CD marker is CD20, which is present in some lymphomas but absent in others. For example, diffuse large B cell lymphoma, or DLBCL, is a very common lymphoma associated with the CD20 marker.

For a given sample of leukemia or lymphoma cells, pathologists can test markers using an entire panel of antibodies that stick to different markers, with built-in positive and negative controls.

Chromosomal Studies

Pathologists may perform molecular and chromosomal studies to look at gene rearrangements and specific changes to the chromosomes. Sometimes inserted or deleted genes inform prognosis.

For instance, in CLL, a specific piece of a chromosome (17p) is lost. Along with the missing chromosome, a gene that helps suppress cancer is often lost. The 17p deletion is found in about 5-10% of people with CLL overall. The 17p deletion CLL is a form of CLL that is harder to treat with conventional chemotherapy.

Summary

Histopathology studies tissue to look for disease. Pathologists perform histopathology in a lab. They examine tissue under a microscope and develop a report of their findings. Histopathology reports include descriptions of the tissue, diagnosis, and prognosis. In addition to evaluating tissue, pathologists may also use other techniques to assess and diagnose cancer.

A Word From Verywell

Histopathology reports can be confusing. That's why it's best not to jump to conclusions before going over them with a healthcare provider. Your report will contain information about your tissue sample, offer a diagnosis or suggestions for further testing, and a prognosis if enough information is available. These details will help a doctor manage your treatment in the future.