A new study published in the journal Diagnostic Cytopathology suggests that the fluid that often builds up around mesothelioma patients’ lungs and abdomen may hold information essential to confirming a diagnosis earlier than other fluid-based tests. The report written by Dr. Suzanne M. Selvaggi of the University of Wisconsin Hospital reviewed 13 years of patient records and found that modern lab markers make testing this fluid a reliable way to diagnose this challenging disease.
Mesothelioma Cases Reviewed Over 13 Years
Despite the fact that the accumulation of fluid in the lungs or abdomen is one of the earliest signs of mesothelioma, the disease is notoriously hard to diagnose based on fluid alone because malignant mesothelioma cells look so similar to benign ones. At best, pathologists have been able to label samples as suspicious for the disease and have required a tissue biopsy for confirmation.
But according to a report published recently, researchers from the University of Wisconsin examined 23 fluid samples that had been collected from mesothelioma patients’ pleura and peritoneum between 2013 and 2025. The samples came from 20 patients, most of whom sought medical assistance after experiencing chest or abdominal pain and shortness of breath.
Mesothelioma Biomarkers Change the Picture
According to the study, mesothelioma diagnostic abilities changed in 2017, when labs began using an expanded panel of stains, with markers for BAP1 and MTAP providing significant promise. These two proteins can normally be found in healthy cells. but often disappear in cancerous mesothelial cells. When mesothelioma cells were stained and those proteins were missing, pathologists could identify the cells as malignant with confidence. Other stains ruled out lung adenocarcinoma, a cancer frequently confused with mesothelioma. Each of the 23 cases were later biopsied, and each of the tissue examinations confirmed the mesothelioma diagnosis.
Mesothelioma research cited in the study shows that BAP1 loss is almost 100% specific to this rare, asbestos-related disease, though testing for BAP1 alone only detects about half to two-thirds of cases. Combining BAP1 and MTAP tests identify a higher percentage of cases.
Mesothelioma Patients Could Benefit from Faster Answers
Mesothelioma patients need answers quickly and with as little complexity as possible: many people suspected of having the disease are older or too frail to be able to tolerate surgery well. The process of draining fluid from the lungs or abdomen can be done quickly and is far less invasive than a surgical biopsy. With fluid buildup being one of the first warning signs, taking a fluid sample can speed early diagnosis and facilitate quick staging and treatment planning.
For now, the American Society of Clinical Oncology’s guidance treats fluid analysis as a screening step to be followed by biopsy, while an international effusion reporting system supports diagnosing from fluid when backed by biomarker tests. with tissue still needed to determine the tumor’s subtype and grade. But having a quick route to initially diagnosing the disease can benefit many patients and is an indication of how diagnosis and treatment have evolved over the last several years.
If you or someone you love has been diagnosed with mesothelioma, the Patient Advocates at Mesothelioma.net are here to help. Contact us today at 1-800-692-8608 to learn more.
