Wilms Tumor 1 (WT-1)

WT-1 is a gene that produces a protein involved in normal cell growth and development. In mesothelioma diagnosis, pathologists use a stain that detects the WT-1 protein in tumor tissue. A positive result helps confirm that a cancer in the pleura or peritoneum is mesothelioma rather than a cancer that spread from the lung, ovary, or elsewhere.

Origin

The WT-1 gene was named after Wilms tumor, a pediatric kidney cancer first described by German surgeon Max Wilms in 1899. The gene was cloned in 1990, and studies in the late 1990s established its value as an immunohistochemical marker for distinguishing mesothelioma from lung adenocarcinoma. It is now part of the standard antibody panels recommended by the International Mesothelioma Interest Group and the College of American Pathologists.

Significance in Asbestos Context

WT-1 staining is one of the key tests pathologists rely on to confirm a mesothelioma diagnosis, especially the epithelioid subtype, where it is positive in roughly 70–95% of cases. Because mesothelioma can look similar under the microscope to other cancers spreading to the pleura or peritoneum, WT-1 (combined with markers like calretinin, cytokeratin 5/6, and D2-40, and with negative results for markers like TTF-1 and CEA) provides the diagnostic certainty that doctors, insurers, and asbestos trusts require. A confirmed mesothelioma diagnosis supported by a documented IHC panel including WT-1 is often essential when filing claims with bankruptcy trusts or in litigation. It is important to understand that WT-1 confirms the type of cancer, not its cause: the link to asbestos exposure is established separately through occupational and exposure history. In sarcomatoid mesothelioma, WT-1 is frequently negative, and a negative result does not rule out the disease. Other markers and the overall pathology are used to make that diagnosis.

Example Sentence

Her pathology report showed strong nuclear staining for WT-1 and calretinin with negative TTF-1, confirming epithelioid mesothelioma of the pleura.

Related Terms

Mesothelioma, Immunohistochemistry (IHC), Calretinin, Cytokeratin 5/6, D2-40, Epithelioid Mesothelioma

Notes

• Request a complete copy of your pathology report, including the full immunohistochemistry panel results, and keep it in your personal records. It is the single most important document for both treatment decisions and any legal claim.
• If WT-1 was not performed and your diagnosis is uncertain or being contested, ask whether additional IHC staining can be ordered on the existing tissue block; most pathology labs retain blocks for years.
• If your diagnosis is sarcomatoid or biphasic mesothelioma and WT-1 is negative, this is expected. Ask your pathologist which markers and histologic features support the diagnosis so you can explain it if questioned.
• Consider requesting a second pathology opinion from a mesothelioma specialty center (such as a National Cancer Institute–designated cancer center), particularly if the IHC panel is incomplete or the diagnosis is in doubt.