A medical study published in February 2026 in Cancer Treatment and Research Communications confirms that Well-Differentiated Papillary Mesothelial Tumor (WDPMT), a rare tumor once considered benign, can progress into diffuse mesothelioma, a deadly cancer.
Researchers reviewed over two decades of medical literature and identified key warning signs that predict when these tumors turn malignant. Their findings have significant implications for patients who may have been told their diagnosis was “indolent” or low-risk.
Why This Matters for Asbestos Exposure Victims
These Tumors Are Linked to Asbestos Exposure
- Of the cases studied where exposure history was available, 43% of patients whose tumors progressed to mesothelioma had a documented history of asbestos exposure (note, however, that many victims of mesothelioma are or were not aware that they were exposed to asbestos, especially to asbestos from contaminated talc-based cosmetic products)
- Pleural (lung lining) WDPMT were most commonly found in men aged 70–80. That’s the same demographic heavily exposed to asbestos in Navy service, shipyards, construction, and industrial work
A “Benign” Diagnosis Can Be Misleading
- WDPMT was historically considered a low-grade, non-cancerous tumor
- This study shows 14 out of 148 patients (9%) progressed to diffuse mesothelioma, sometimes after more than a decade
- Progression occurred as long as 15 years after the original diagnosis
- Many patients who were told they had a benign lesion may actually have, or develop, a compensable malignancy
Two Key Red Flags for Well-Differentiated Papillary Mesothelial Tumor (WDPMT) Progression
Researchers identified two major factors associated with progression to mesothelioma:
- BAP1 Loss: A specific protein marker detectable by pathology testing. When BAP1 is absent on tumor cells, the study found a strong association with cancer progression. The authors recommend this testing be mandatory for all WDPMT diagnoses.
- Multifocality: When tumors appear at multiple sites simultaneously, the risk of progression is significantly elevated. 75% of peritoneal (abdominal) WDPMT cases that progressed were multifocal.
The Diagnostic Line Between "Pre-Cancer" and Cancer Is Blurring
- The study confirms that WDPMT with BAP1 loss is morphologically indistinguishable from mesothelioma in situ (MIS), a pre-invasive stage of mesothelioma
- The authors recommend that any WDPMT with BAP1 or MTAP loss be reclassified as mesothelioma in situ, meaning what was called a “benign tumor” may legally and medically constitute a cancer diagnosis
What This Could Mean for the Legal Rights of People Diagnosed With WDPMT
If you or a loved one has been diagnosed with WDPMT, particularly with:
- A history of asbestos exposure (including talc-based cosmetics)
- BAP1 or MTAP loss on pathology testing
- Multiple tumor sites (multifocal disease)
- A diagnosis that later progressed to diffuse mesothelioma
Then, you may have significant legal rights against the companies responsible for your asbestos exposure and could secure compensation for mesothelioma.
Don’t assume a “benign” diagnosis means you have no claim. This research shows that the line between WDPMT and mesothelioma is thinner than previously understood and asbestos exposure may be the underlying cause of both.
This summary is for informational purposes only and does not constitute legal or medical advice.
Contact our office to discuss your specific diagnosis and exposure history with an experienced asbestos litigation attorney.