The Who, What, Where, When and Sometimes, Why.

Contents of a Pathology Report

Pathology reports are written in medical language because they are prepared for health care providers. This can make some of the wording hard to understand.

However, understanding the basic parts of the report can help you be better informed about your diagnosis.

Different pathology labs may use different terms to describe the same information. So, your report may not have the exact wording found here.

Needle biopsy reports contain less information than surgical biopsy reports.

Also, some tests are only done when invasive breast cancer or certain types of breast cancer are found. If no cancer is found in the tissue or if your diagnosis is ductal carcinoma in situ (DCIS), many of the sections described below will not be on your report.

Find questions to ask your health care provider concerning your pathology results.

For people who get neoadjuvant (before surgery) therapy

Some information on a pathology report is a bit different for people who get neoadjuvant therapy compared to those who get surgery as their first treatment.

Learn about pathology reports after neoadjuvant therapy.

Diagnosis or final diagnosis

This is the most important section of the report. It gives the pathologist’s final diagnosis and may include information on the tumor such as size, type, grade, hormone receptor status and HER2 status.

If lymph nodes were removed, the status of these lymph nodes will also be included.

This information may appear grouped together or as separate sections.

Microscopic description

The microscopic description details what the pathologist saw and measured when they looked at the biopsy tissue under a microscope.

Tumor size

Tumor size is most often reported in centimeters or millimeters (1 inch = 2.54 centimeters = 25.4 millimeters).

The best way to measure tumor size is under a microscope, especially for small tumors.

The longest length of the tumor in the tissue removed during surgery is reported as the tumor size.

The tumor size may be much smaller than the size of the tissue sample. The measurement of entire sample is reported in the gross description.

In general, the smaller the tumor, the better the prognosis (chance of survival) tends to be.

Learn about tumor size and breast cancer staging.

Non-invasive vs. invasive

Ductal carcinoma in situ (DCIS) is a non-invasive breast cancer.

With DCIS, the cancer cells are contained within the milk ducts. It’s called “in situ” (which means “in place”) because the cancer cells have not spread to nearby breast tissue.

Invasive breast cancer has spread from the original site (the milk ducts or lobules) into the nearby breast tissue, and possibly to nearby lymph nodes and/or other parts of the body.

Tumor grade

For invasive breast cancers, the pathologist notes the shape of the cancer cells and how many of the cancer cells are in the process of dividing to determine the histologic grade.

Tumor grade describes the structure of the cells and is different from tumor stage. It’s reported using either a number system or words.

In general, the more the cancer cells look like normal breast cells, the lower the grade and the better the prognosis (chances for survival) tends to be.

The most common grading system is the Nottingham system:

  • Grade 1. The tumor cells look the most like normal tissue and are slow-growing (well-differentiated).
  • Grade 2. The tumor cells fall somewhere in between grade 1 and grade 3 (moderately-differentiated).
  • Grade 3. The tumor cells look very abnormal and are fast-growing (poorly-differentiated).

Nuclear grade

The nuclear grade describes how closely the nuclei of cancer cells look like the nuclei of normal breast cells.

In general, the higher the nuclear grade, the more abnormal the nuclei are and the more aggressive the tumor cells tend to be.

The nuclear grade is a part of overall tumor grade.

Hormone receptor status

Hormone receptors are proteins found inside some cancer cells. When hormones attach to hormone receptors, the cancer cells with these receptors grow.

  • Hormone receptor-negative breast cancers are estrogen receptor-negative (ER-negative) and progesterone receptor-negative (PR- negative). These cancers do not express hormone receptors. This means they have few or no hormone receptors.
  • Hormone receptor-positive breast cancers are estrogen receptor-positive (ER-positive) and progesterone receptor-positive (PR-positive). These cancers express hormone receptors. This means they have a lot of hormone receptors.

The standard of care is to test all breast cancers for hormone receptor status. The hormone receptor status of your tumor helps guide your treatment.

If the tumor is ER-positive and PR-positive, your treatment will include hormone therapy (such as tamoxifen or an aromatase inhibitor). Hormone therapy prevents the cancer cells from getting the hormones they need to grow and may stop tumor growth.

Sometimes, a breast cancer is ER-positive, but PR-negative. Because current hormone therapies are designed to treat ER-positive cancers, these cases are treated the same as breast cancers that are positive for both hormone receptors.

Hormone receptor-negative breast cancers are not treated with hormone therapy.   

If the tumor is ER-negative, PR-negative and HER2-negative, you may see the tumor described as triple negative breast cancer.

Learn about hormone receptor status and prognosis (chances for survival)

HER2 status

HER2 (human epidermal growth factor receptor 2) is a protein that appears on the surface of some breast cancer cells. It may also be called HER2/neu or ErbB2. 

The HER2 protein is an important part of the pathway for cell growth and survival.

The standard of care is to test all breast cancers for HER2 status. HER2 status helps guide your treatment.

Testing for HER2 status

The main tests for HER2 status are:

  1. Immunohistochemistry (IHC), which detects the amount of HER2 protein on the surface of the cancer cells
  2. Fluorescence in situ hybridization (FISH), which detects the number of HER2 genes in the cancer cells

Most often, IHC is the first test done. If the score is +2 (borderline), the tumor is sent for FISH testing to confirm the status.

Results of an IHC test

Score is 0 or 1+

Tumor is HER2-negative

Score is 2+

Results are unclear and should be confirmed by FISH

Score is 3+

Tumor is HER2-positive

Results of a FISH test

Negative (non-amplified)

The tumor is HER2-negative

Positive (amplified)

The tumor is HER2-positive

HER2 status and metastatic breast cancer

Learn about HER2 status and metastatic breast cancer, including HER2-low metastatic breast cancer.

HER2 status and early breast cancer

  • HER2-negative breast cancer cells have little or no HER2 protein.
  • HER2-positive breast cancer cells have a lot of HER2 protein. You also may hear the term HER2 over-expression.

HER2-positive cancers can benefit from HER2-targeted therapies, such as trastuzumab (Herceptin), which directly target the HER2 receptor.

Trastuzumab and other HER2-targeted therapies are not used to treat HER2-negative cancers.

If the tumor is HER2-negative, ER-negative and PR-negative, you may see the tumor described as triple negative breast cancer.

Learn more about HER2 status and prognosis (chances for survival).

Learn more about treatment with trastuzumab (Herceptin) and other HER2-targeted therapies.

Tumor margins

When breast cancer is surgically removed (during a surgical biopsy, lumpectomy or mastectomy), a rim of normal tissue surrounding the tumor is also removed. This rim is called a margin.

The pathologist looks at the margins under a microscope and determines whether or not they contain cancer cells. This helps show whether or not all of the tumor was removed.

Negative margins (also called clean, not involved or clear margins)

  • The outer edges of the margins do not contain cancer cells. (There’s only normal tissue at the edges of the tissue removed from the breast.)
  • In most cases, no more surgery is needed.

Positive margins (also called involved margins)

  • The margins contain cancer cells.
  • More surgery may be needed to get negative margins. (Discuss the details with your surgeon.)
  • Sometimes it’s not possible or necessary to get negative margins due to the tumor location (for example, if it’s at the chest wall or right under the skin).

Close margins

  • The cancer cells approach, but don’t touch the edge of the breast tissue removed.
  • More surgery may or may not be needed, especially with ductal carcinoma in situ (DCIS). (Discuss the details with your surgeon.)
  • To further make sure the entire tumor was removed, the removed breast tissue may be X-rayed. This is useful when microcalcifications were found on a mammogram and are related to the cancer. Depending on the results of the X-ray, more tissue may be removed at the time of the surgery.
  • If microcalcifications were found on a mammogram before surgery, another mammogram may be done after surgery to ensure all the microcalcifications were removed.

Learn more about tumor margins.

Lympho-vascular invasion (angiolymphatic invasion)

Lympho-vascular invasion occurs when cancer cells enter lymph channels or small blood vessels. This may suggest a more aggressive tumor.

Lymph node status

If lymph nodes in the underarm area (axillary lymph nodes) were removed during surgery, the pathologist looks at them under a microscope and determines whether or not they contain cancer.

  • Lymph node-negative means none of the axillary lymph nodes contain cancer.
  • Lymph node-positive means at least one axillary lymph node contains cancer.

In general, lymph node-negative breast cancers have a better prognosis (chances for survival) than lymph node-positive breast cancers.

Learn more about lymph node status and prognosis.

Learn more about lymph node assessment.

Learn about lymph node status and breast cancer staging.

Other information in a pathology report

The following items are included in all pathology reports, but don’t impact prognosis (chances for survival) or treatment.

Patient information

This section of the report has basic information including your name, medical record number, date of birth, age and sex, date of the breast biopsy and name of the doctor who ordered the report (most often your surgeon).

Be sure to check this information to make sure you have the correct pathology report.

Specimen(s) received (specimen source/specimen submitted)

This section records the location in the breast where the biopsy sample(s) was removed. It may simply state left or right breast, or it may give more detail.

It also includes the date the pathologist received the tissue.

Procedure (description of procedure)

This is a description of the type of biopsies used to remove the tissue sample and lymph nodes (if lymph nodes were removed).

Clinical history (clinical information/clinical diagnosis/pre-operative diagnosis)

The clinical history describes the initial diagnosis before the breast biopsy and sometimes, a brief summary of your symptoms.

The location of the tumor biopsy is also noted (for example, left or right breast).

If you had breast cancer in the past and the biopsy tissue is available, the pathologist will often review this tissue to distinguish the recurrence of a past tumor from a new breast cancer.

Gross description (macroscopic description)

One of the first things pathologists do when they receive biopsy tissue is take measurements and record a description of the tissue as it appears to the naked eye (without a microscope).

This gross description may include the size, weight, color, texture or other features of the tissue and any other visual notes.

If there are multiple samples, there’s often a separate gross description section for each sample. In these cases, the pathologist gives a reference number or letter to each tissue sample to avoid confusion.

The gross description also includes information on how the sample was handled once it reached the pathologist.  

Pathologist’s signature

The pathologist signs and dates the report (most often, electronically).

Information sometimes seen on a pathology report

The following items don’t impact prognosis (chances for survival) or treatment and may not appear on your report.

Some of these tests are only done for certain diagnoses. Others aren’t routinely done because they don’t predict prognosis better than standard measures or because they aren’t reliable measures for all tumors.

Immunohistochemistry (IHC) for prognostic markers

Beyond HER2 status testing, IHC can detect other molecular markers that may give information on prognosis.

Proliferation rate (Ki-67, MIB1)

The proliferation rate is the percentage of cancer cells actively dividing. In general, the higher the proliferation rate, the more aggressive the tumor tends to be.

Proliferation rate could be a good predictor of prognosis. However, there are issues related to its measurement. Although it may be assessed at some medical centers, it’s not standard of care.

The Ki-67 test is a common way to measure proliferation rate. When cells are growing and dividing (proliferating), they make proteins called proliferation antigens. Ki-67 is a proliferation antigen.

MIB1 is the antibody most often used to label the Ki-67 antigen. The more cells MIB1 attaches to in a tissue sample, the more likely the tumor cells are to grow and divide rapidly.

The result of this test is reported as the percentage of Ki-67-positive cells (the proportion of cancer cells in the process of dividing). A higher value shows a higher proliferation rate.

Learn more about understanding your pathology report.

Updated 03/06/23