How to Read the Gross Description Section of Your Pathology Report

Section Editor: Jason Wasserman MD PhD FRCPC
November 9, 2026

The gross description is the part of your pathology report that describes your tissue as it looked to the naked eye, before any slides were made. It records how the sample arrived and what it looked like. It also records its size and how it was cut up for the microscope. In this setting, “gross” means “visible without a microscope.” Some reports call this section the gross examination or the macroscopic description.

This article explains how to read the gross description section of your pathology report. It covers the measurements, the descriptive words, and the list of codes that often appears at the end. It also explains why the gross description can differ from the final diagnosis.

What is the gross description?

The gross description is a written record of the gross examination, which is the first thing that happens to your tissue in the pathology laboratory. Before anything is placed under a microscope, the tissue is identified and measured. It is then described and cut into small pieces. Only a small part of a large specimen fits on glass slides, so this step determines which areas the pathologist will see.

Most of the gross description is written for the laboratory. It lets anyone reading the report later know exactly what was received and which areas were examined. Some of it, such as the size of a mass or its distance from the edge of the tissue, also helps explain the final diagnosis.

In many reports, the gross description appears after the final diagnosis, near the end. Our section-by-section guide to the pathology report shows where it sits among the other sections.

Who writes the gross description?

A pathologist’s assistant often writes the gross description of a surgical specimen. These are specially trained professionals who examine and dissect tissue under the supervision of a pathologist. In some hospitals, a pathologist or a doctor training in pathology performs the gross examination.

The person examining the tissue usually dictates the description as they work, so it is written in short, technical sentences. The pathologist who signs your report is responsible for the whole report, including the gross description. For complex specimens, the pathologist may examine the tissue alongside the pathologist’s assistant before it is cut.

What does the gross description of a small biopsy look like?

The gross description of a small biopsy is usually short, often two or three lines. It names the specimen and confirms the label. It then gives the size and says how much was sent for slides. Here is an example from a skin biopsy:

A. SKIN, LEFT FOREARM, PUNCH BIOPSY:
Received in formalin, labeled with the patient’s name and “left forearm,” is a tan skin punch biopsy, 0.4 cm in diameter and 0.5 cm in depth. The specimen is bisected and submitted entirely in cassette A1.

Each part of this description has a purpose. “Received in formalin” means the tissue arrived in a preservative. The label confirms the sample belongs to you and came from the right place. “Bisected” means it was cut in half, and “submitted entirely” means all of it was processed for the microscope.

For a small biopsy, a short gross description is normal. It does not mean the sample was examined quickly or carelessly. Most of the information about a biopsy comes from the microscopic examination and the final diagnosis.

What does the gross description of a larger specimen look like?

The gross description of a larger surgical specimen, such as a lumpectomy or a section of bowel, can run to several paragraphs. It describes the whole specimen first, then any mass or abnormal area, and then the relationship between the mass and the tissue edges. Here is a shortened example from a breast lumpectomy:

B. BREAST, RIGHT, PARTIAL MASTECTOMY:
Received fresh, labeled with the patient’s name and “right breast lumpectomy,” is an oriented piece of fibrofatty tissue, 6.5 x 5.0 x 3.2 cm. A short suture marks the superior margin, and a long suture marks the lateral margin. The margins are inked: superior blue, inferior green, medial red, lateral yellow, anterior orange, posterior black. Serial sectioning reveals a firm, tan-white, ill-defined mass, 1.8 x 1.5 x 1.2 cm. The mass is 0.4 cm from the posterior margin and 1.1 cm from the superior margin. All other margins are more than 1.5 cm away. The remaining tissue is unremarkable.

This kind of description often contains several pieces of information that patients notice:

Orientation. The surgeon marks the specimen, often with stitches of different lengths, so the laboratory knows which side faced which direction in your body. Without orientation, the pathologist could tell that the tumor reached an edge but not which edge.
Ink. The outer surface is painted with colored ink, a different color for each side. The ink shows up under the microscope and marks the true surgical edge. Our article on surgical margins explains how the ink helps determine whether a margin is negative or positive.
The mass. The size and color of any mass are recorded, along with how firm it feels and whether its edge is smooth. A firm, tan-white mass with an irregular edge raises concern for cancer, but only the microscope can confirm what it is.
Distances to the margins. Measure the distance from the mass to each edge with a ruler. These distances guide which areas are sampled, and the final distances are confirmed under the microscope.

What do the common words in the gross description mean?

The gross description uses a small set of words repeatedly, and most describe how the tissue was handled or what it looked like. These are the words patients ask about most often:

Received fresh or received in formalin. Fresh tissue arrives without preservative, usually straight from the operating room. Formalin is the liquid preservative used for almost all pathology samples.
Labeled with. The words written on the container. Recording the label is one check that confirms the sample belongs to you.
Tan, tan-white, or pink. The color of the tissue. Color helps the pathologist identify abnormal areas, but it rarely provides a diagnosis on its own.
Firm, soft, or rubbery. How the tissue feels. Many cancers are firmer than the surrounding tissue, though scar tissue can also be firm.
Well-circumscribed or ill-defined. Whether a mass has a clear, smooth border or blends into the surrounding tissue.
Serially sectioned or bisected. Serially sectioned means sliced like a loaf of bread so that each slice can be examined. Bisected means cut in half.
Submitted entirely or in toto. All of the tissue was processed for the microscope. In toto is Latin for “in total.”
Representative sections. Only selected areas were processed, chosen because they best show the mass, the margins, and the normal tissue. This is standard for large specimens.
Fragments, aggregated. The sample arrived in several small pieces, and the measurement is of the pieces gathered together.
Unremarkable. Nothing abnormal was seen with the naked eye. This does not rule out a change that can only be seen under the microscope.
Grossly. Means “to the naked eye.” A phrase such as “grossly uninvolved margins” describes what could be seen before slides were made, not the final result.

Looking up a word in your report?

Our Pathology Dictionary explains individual terms you may see in the gross description, such as “specimen,” “mass,” and “calcification.”

How are measurements written in the gross description?

Measurements in the gross description are usually given in centimeters, with three numbers for a piece of tissue. A measurement such as “6.5 x 5.0 x 3.2 cm” gives the specimen’s length, width, and depth. A mass is measured the same way, and the largest of the three numbers usually matters most.

Some specimens are also weighed, usually in grams. Weight is recorded for organs such as the uterus, thyroid, and prostate, where the size of the whole organ can help explain the findings. Very small pieces of tissue may be measured in millimeters.

Gross measurements are not always final. The size of a tumor used for staging is confirmed by combining the gross measurement with what the pathologist sees under the microscope. The final size appears in the final diagnosis or the synoptic report, and that is the number to use.

What is the list of codes at the end of the gross description?

The list of codes at the end of many gross descriptions is called the cassette key, section code, or block summary. It records which piece of tissue went into which cassette. A cassette is a small plastic box that holds the tissue while it is processed and embedded in wax. Each cassette becomes a tissue block, and slides are cut from each block.

Representative sections are submitted as follows:
B1: mass with closest (posterior) margin
B2-B4: remainder of mass
B5: superior margin
B6-B9: remaining margins
B10: unremarkable breast tissue

The letter matches the specimen part, so “B” means the second specimen listed in the report. The number identifies the cassette. Most patients do not need to read this list closely. It matters later if more tests are needed, because it tells the laboratory which block holds the tumor. For example, a test such as immunohistochemistry would usually be done on block B1 or B2 in this example.

Why does my report mention formalin, cold ischemia time, or fixation time?

Some gross descriptions record when the tissue was removed, when it was placed in formalin, and how long it stayed there. These times appear most often on breast specimens, because they affect the accuracy of tests for treatment markers. Formalin preserves the tissue by firming up its proteins, a process called fixation.

Cold ischemia time. The time between removing the tissue from your body and placing it in formalin. The proteins in tissue start to break down during this time, so a shorter time is better.
Fixation time. How long the tissue stayed in formalin before processing. For breast tumors tested for estrogen receptor and progesterone receptor, guidelines call for 6 to 72 hours in formalin. These guidelines come from the American Society of Clinical Oncology and the College of American Pathologists (2020 update).

Fixation also affects turnaround time. A large specimen needs to sit in formalin before it can be cut well, and tissue containing bone needs extra days to soften. Our article on how long pathology results take explains the other steps.

Why might the gross description differ from the final diagnosis?

The gross description can differ from the final diagnosis because it records only what can be seen with the naked eye. The microscope often adds to it or corrects it. When they disagree, the final diagnosis counts.

Something looked abnormal but was not. A firm area that looked like a tumor may turn out to be scar tissue or fat necrosis under the microscope.
Something looked normal but was not. Some changes, such as small areas of cancer or precancerous cells, may not be visible to the naked eye. Tissue described as unremarkable can still contain an important finding.
The tumor may be larger or smaller than it looked. Cancer cells can extend beyond the visible edge of a mass, or part of a visible mass may be scar or inflammation.
The tissue shrank. Tissue shrinks in formalin and during processing. In one study of kidney tumors, the tumors measured about 5% smaller after formalin and about 11% smaller on the slides than when fresh. Fatty tissue and skin can shrink more.

For these reasons, the pathologist reviews the gross description alongside the slides before writing the final diagnosis. If the final report gives a different size or distance than the gross description, your care team will use the final number.

Can a specimen be examined without a microscope?

Some specimens are examined by gross examination only, without any slides. The report may say “gross examination only” or give a short gross diagnosis. This happens when looking at the specimen answers every question that matters.

Examples include teeth, orthopedic hardware such as a removed screw or joint implant, and other foreign objects. Which specimens are handled this way depends on each hospital’s policy. If anything unexpected is seen, the specimen is sent for slides as usual.

What happens to the rest of my tissue?

Tissue that was not placed in a cassette is usually kept in formalin for a short time after the gross examination. This allows the pathologist to go back and take more samples if the slides raise a new question. In laboratories accredited by the College of American Pathologists, leftover wet tissue is kept for at least two weeks after the final report.

Laboratories keep the tissue blocks and slides made from your sample much longer. The same College of American Pathologists rules require them to be kept for at least ten years, and rules in other countries vary. These blocks can be used for new tests years later, or sent to another hospital for a second opinion.

Some hospitals ask permission to keep leftover tissue for research or a tumor bank. This is separate from your diagnosis, and the gross description may note that tissue was set aside for that purpose.

Next: the microscopic description

After the gross examination, the tissue is processed into slides and examined under the microscope. Our article on the microscopic description section explains the next part of your report.

Questions to ask your doctor

What size was the tumor in my final report, and how does it compare with the gross description?
Was all of my tissue examined under the microscope, or were representative sections taken?
Does the final report confirm the margin distances given in the gross description?
Did my surgeon orient the specimen, and which margin was closest to the tumor?
Were any areas described as abnormal in the gross description found to be benign under the microscope?
Which tissue block would be used if more tests are needed?
Was the cold ischemia time or fixation time recorded for my specimen, and did it affect any test results?
How long will my tissue blocks and slides be kept?
Can my slides and blocks be sent to another hospital for a second opinion?