An imaging report describes images taken inside your body, such as a mammogram, CT scan, or MRI. A pathology report describes tissue or cells that were removed from your body and examined under a microscope. Both reports often appear in the same patient portal, and both can use words like “mass” or “suspicious.” They answer different questions, though, and different doctors write them.
This article explains how to tell the two kinds of reports apart and how they work together to reach a diagnosis. It also explains why the two reports sometimes seem to disagree and who to ask about each one.
The main difference between a pathology report and an imaging report is what the doctor actually examined. An imaging report is based on pictures, while a pathology report is based on the tissue or cells themselves.
Imaging can show where something is and what it looks like from the outside. Pathology shows what it is made of. That is why most diagnoses of cancer depend on a pathology report, even when the abnormal area was first found on a scan.
Imaging and pathology reports follow different layouts, and a few headings usually make the report type clear. If you are unsure which kind of report you are reading, look at the headings and the words used to describe what was found.
Some reports describe a procedure that combines both. An “ultrasound-guided breast biopsy” report, for example, is usually written by the radiologist who performed the biopsy. It describes how the sample was taken but does not give the diagnosis. The diagnosis comes later, in a separate pathology report on the tissue.
The same applies to a cytology report, such as a Pap test or a fine needle aspiration. Pathologists write cytology reports, even though they examine cells rather than tissue.
Imaging cannot usually diagnose cancer on its own because it shows the shape of an abnormal area, not the cells inside it. Many noncancerous conditions look similar to cancer on a scan. Infections, scars, and benign tumors such as cysts can all appear as a mass or a lesion.
To know for certain, doctors usually need a tissue sample. The sample is taken by biopsy or removed during surgery. The pathologist then examines the cells directly under the microscope and can often run additional tests on the same tissue.
There are a few exceptions. Some liver cancers in people with cirrhosis, for example, can be diagnosed from imaging alone when the scan shows a very typical pattern. These exceptions are uncommon, and your care team will explain when one applies to you.
Imaging and pathology are usually two steps in the same process. Imaging often finds the problem, pathology identifies it, and imaging is then used again to see whether a cancer has spread.
After an image-guided biopsy, the radiologist and the pathologist check that the two results make sense together. This step is called radiologic-pathologic correlation. If the scan looked like cancer but the biopsy shows only normal tissue, the needle may have missed the abnormal area. In breast biopsies, for example, the pathologist may cut deeper into the tissue to look for the microcalcifications seen on the mammogram.
When the results still do not fit together, they are called discordant. In that case, the care team may consider a repeat biopsy, surgical removal of the area, or another scan after a short interval. A discordant result does not mean anyone made an error. It means the team needs more information before it can be confident.
Many imaging reports end with a category or score that summarizes how worrying a finding looks. These categories belong to the imaging report, not the pathology report. They describe the level of suspicion on the images, not a diagnosis.
The best-known example is BI-RADS, which is used for mammograms, breast ultrasound, and breast MRI. The current version is the American College of Radiology’s BI-RADS Atlas, 5th edition, published in 2013. Its categories are:
Even a BI-RADS 4 or 5 finding is not a diagnosis. Most breast biopsies do not find cancer, and only the pathology report can confirm whether cancer is present. Similar imaging systems exist for other organs, such as Lung-RADS (version 2022) for lung cancer screening CT scans.
Pathology has its own category systems, separate from imaging scores. For example, a thyroid nodule may receive a score on ultrasound. If a needle sample is then taken, the pathology report uses a different system: the Bethesda System for Reporting Thyroid Cytopathology, 2023 edition.
The size of a tumor in a pathology report is often different from its size in an imaging report. This is common and usually doesn’t mean either report is wrong, because the two doctors measure in different ways.
On a scan, the radiologist measures what the picture shows. That can include swelling or scar tissue around a tumor, which makes it look larger. It can also miss tiny extensions of the tumor that are too small to see on the scan, which makes it look smaller. In one study of pancreatic cancer, the size under the microscope was about 4 to 6 mm larger than on CT or MRI on average. The gap varied widely between patients in both directions.
The pathologist measures the tumor directly and confirms its edges under the microscope. After the tumor is removed, the pathologic size is usually used for the T stage in the pathology report. Our dictionary entry on the tumor stage (T stage) explains how size affects the stage.
Lymph node findings on imaging and pathology are based on different evidence, so they do not always match. On a scan, a lymph node is described as abnormal mainly because of its size, shape, or activity on a PET scan. Lymph nodes can look enlarged or active because they are fighting an infection, not only because they contain cancer.
The pathologist can see whether cancer cells are actually present in the lymph node. A node that looked normal on imaging may contain a small amount of cancer. A node that looked abnormal may contain no cancer at all.
This is why staging uses two kinds of lymph node results. A clinical N stage, such as cN0, is based on imaging and physical examination. A pathologic N stage, such as pN0, is based on lymph nodes examined under the microscope. Our article on lymph nodes in your pathology report explains how the pathologist examines and counts lymph nodes.
The best person to explain your imaging report is the doctor who ordered the scan. They know why the test was done and can explain the findings in the context of your health. They can also contact the radiologist if a finding needs clarification.
MyPathologyReport.com explains pathology reports, so our articles and our pathology assistant, Osler, do not interpret imaging reports. For general information about imaging tests, RadiologyInfo.org is a patient resource from the Radiological Society of North America and the American College of Radiology. If your imaging report has not appeared in your patient portal, our article on getting your results explains who to contact.
When you have both reports, bring them to your appointment together. Your doctor can explain how the imaging findings and the pathology diagnosis fit together and what they mean for your next steps.