How to Understand Your Mesothelioma Pathology Report
Written by Kate Placzek, PhD on November 7, 2026
A pathology report summarizes what a pathologist finds after examining a tissue sample from a biopsy or surgery. It includes the diagnosis and other details about the sample. If mesothelioma is found, the report may provide more information about the cancer.
Below, we explain how to read a mesothelioma pathology report, including common sections, medical terms, and test results you may encounter. This information can help you prepare questions for your doctor about your individual findings and how they relate to your diagnosis and treatment.
How Does a Pathologist Prepare the Report?
A pathologist is a doctor who studies tissue and cells to look for signs of disease. For suspected mesothelioma, the pathologist examines a biopsy sample under a microscope and may perform other tests. These findings can confirm whether cancer is present and provide details about the tumor.
Pathology is one part of the diagnostic process. Doctors also consider imaging results, symptoms, medical history, and other test results when making a diagnosis and planning care.
What You May See on a Mesothelioma Pathology Report
Pathology reports can look different depending on the type of sample, how it was collected, and the tests performed. Still, many reports include some of the same basic information. Your report may not have every section described below, and the wording can vary between laboratories.
- Patient or identifying information: Lists details such as the patient’s name, date of birth, and medical record number. It may also include the date the sample was collected and the name of the doctor who ordered the test.
- Clinical information or clinical history: Gives the pathologist background that may help with the diagnosis. This can include symptoms, imaging findings, the reason for the biopsy, or a suspected diagnosis.
- Gross description: Describes the size, color, shape, and other features of the tissue that can be seen without a microscope.
- Microscopic description: Explains what the pathologist sees when examining the tissue and cells under a microscope. Not all pathology reports include this section.
- Final diagnosis: Summarizes the pathologist’s findings and identifies the diagnosis. If mesothelioma is found, this section may include more details about the cancer.
- Comments: Provides added context about the findings. It may also mention tests that are still pending or recommend additional testing.
Understanding a Mesothelioma Diagnosis
The diagnosis section explains what the pathologist found in the tissue sample. If the sample shows mesothelioma, the report may also name the cell type, sometimes called the histologic type. Cell type is based on how the cancer cells look under a microscope.
The three main mesothelioma cell types are:
- Epithelioid: The most common cell type. It is often linked to a better prognosis and may respond better to treatment than other cell types.
- Sarcomatoid: The least common cell type. It tends to grow and spread faster than epithelioid mesothelioma.
- Biphasic: A mix of both epithelioid and sarcomatoid cells.
The report may also describe how the tumor is growing or whether it has reached nearby tissue. These details can help doctors understand the extent and features of a patient’s cancer. Doctors also use imaging, cancer stage, overall health, and other information when discussing prognosis and treatment.
What Do Immunohistochemistry Results Mean?
Immunohistochemistry (IHC) is testing done in the laboratory using tissue already collected during a biopsy or surgery. Special stains are applied to the tissue to show whether certain proteins are present. The pattern of these proteins can help a pathologist confirm mesothelioma or distinguish it from cancers that may look similar.
A pathology report may list markers such as:
- Calretinin
- WT-1
- D2-40
- Cytokeratin 5/6
Results may be listed as positive or negative. But one marker alone cannot confirm or rule out mesothelioma. Pathologists look at the overall pattern of IHC results along with the appearance of the cells and other findings.
What if Your Pathology Report Has Additional Testing or Unclear Results?
Sometimes a pathologist needs more information before reaching a final conclusion. This may include additional IHC stains, other laboratory tests, or a review by a pathologist with experience in mesothelioma.
- What is the final diagnosis listed on my pathology report?
- If mesothelioma was found, what cell type do I have?
- What do my immunohistochemistry (IHC) results mean?
- Are any test results still pending?
- Do I need any additional testing?
- Does my pathology report provide information about my cancer stage?
- Would it be helpful to have another pathologist review my tissue sample?
Some results may be added later in an addendum, which is an update to the original pathology report. A pending test or incomplete report does not necessarily mean there is a problem. It may simply mean more testing is needed.
Patients can ask their care team when to expect additional results. Their doctors can also explain how the pathology findings fit with imaging and other information used to make a diagnosis.
Sources
Free Mesothelioma Treatment Guide
Kate Placzek, PhD, is a medical writer and editor with years of experience as a scientific researcher. For Mesothelioma.com, she helps ensure our content stays accurate and easy to understand.
