Pleural mesothelioma is a cancer that starts in the pleura, the thin lining around the lungs and chest wall. It is the most common form, making up more than 8 out of 10 mesotheliomas, according to the American Cancer Society. Most cases trace back to breathing in asbestos fibers, often decades earlier. A pathology report may call it malignant pleural mesothelioma or diffuse pleural mesothelioma. Both names mean the same disease. It is not lung cancer, though it grows around the lung.

Asbestos is by far the main cause of pleural mesothelioma. The National Cancer Institute reports a history of asbestos exposure in about 70% to 80% of mesothelioma cases. Most of that exposure happened at work, in shipyards, construction, plumbing, insulation, railroads, mining, and factories. Fibers also came home on work clothes, so some family members were exposed that way. Some people can point to no exposure at all, and that does not make the diagnosis wrong. Rarer causes include erionite, past radiation to the chest, and an inherited gene change.

Early pleural mesothelioma symptoms are usually shortness of breath and pain in the side of the chest or lower back. Others include a cough that will not go away, trouble swallowing, and hoarseness. Many people also have fatigue, appetite loss, unexplained weight loss, fever, or night sweats. Much of this comes from fluid building up around the lung and pressing on it. These look like pneumonia or ordinary aging, which is why the diagnosis is often missed. If a chest problem is not clearing up, mention any asbestos history.

Yes. A pleural effusion, fluid collecting between the lung and the chest wall, is very common in pleural mesothelioma. Published series of diagnosed patients report it in 54% to 90% of cases, and it is often the first sign. Draining it with a needle, called thoracentesis, usually brings quick relief, though fluid often returns. Talc pleurodesis seals the space with powder, but works in only about 30% of mesothelioma patients. A soft catheter left in place drains fluid at home and means fewer hospital days.

Yes, mesothelioma cells can sometimes be found in pleural fluid, but that fluid alone often cannot confirm the diagnosis. Drained fluid is checked in a lab by a test called cytology. Published reviews find cytology detects mesothelioma in only about 30% of cases, and as low as 16% in some studies. So a normal fluid result does not rule cancer out. Doctors usually need a tissue sample, called a biopsy, taken through a small camera procedure. Special stains on that tissue separate mesothelioma from other cancers.

Pleural mesothelioma is diagnosed with imaging plus a tissue biopsy. A chest x-ray or CT scan usually comes first and may show fluid or thickening of the lung lining. A PET or MRI scan can help tell scar tissue from cancer. A biopsy is still needed, because under the microscope mesothelioma looks a lot like lung cancer. Special lab stains are required to tell them apart, and that testing takes time. If a first biopsy is unclear, it is fair to ask for a second pathology opinion.

No, pleural thickening on a scan does not automatically mean cancer. Asbestos also causes benign, meaning non-cancerous, changes such as pleural plaques and diffuse pleural thickening. Those mark past exposure rather than a tumor. Thickening still raises a question worth answering, especially when fluid is also present. A PET scan can help separate scar tissue from cancer, but only a biopsy settles it. With an asbestos history, ask for review by a doctor who sees asbestos disease often.

Pleural mesothelioma has three main cell types, and the type affects treatment and outlook. About 6 out of 10 are epithelioid, which usually grows more slowly. About 1 out of 10 are sarcomatoid, the most aggressive, and 3 out of 10 are biphasic, a mix of both. Cell type helps guide treatment, but it does not rule out immunotherapy, drugs that help the immune system fight cancer. In the CheckMate 743 trial, immunotherapy helped both groups live longer than chemotherapy did, and the gain was largest in non-epithelioid disease.

Pleural mesothelioma is staged 1 through 4 using the TNM system, which describes the tumor, lymph nodes, and distant spread. In stage 1 the cancer is limited to the lining on one side of the chest. Stage 2 means it has grown deeper or reached lymph nodes on that same side. Stage 3 means wider growth into nearby structures or more distant lymph nodes. Stage 4 means it has spread to distant organs. Doctors now use version 9 of this system, from 2024, so older records may show a different number.

Pleural mesothelioma usually spreads locally first, growing along the chest lining. From there it reaches nearby structures such as the chest wall, the diaphragm, and the covering of the heart. It can then involve lymph nodes in the chest. In advanced disease it can reach the bones, the other side of the chest, and the abdominal lining, called the peritoneum. Because it grows as a rind around the lung rather than one lump, doctors measure spread differently than in many cancers.

Life expectancy for pleural mesothelioma varies widely, and no single number predicts one person's course. American Cancer Society figures from SEER cover people diagnosed in the United States from 2015 to 2021. Those figures group people by how far the cancer had spread, not by stage number. Five-year relative survival was 23% localized, 15% regional, 11% distant, and 15% overall. Relative survival compares people with mesothelioma to people of the same age in the general population. That separates out deaths from other causes, and these figures cover everyone diagnosed, whatever treatment they had.

Stage 3 and stage 4 are advanced, but treatment can still extend life and ease symptoms. SEER groups cases by how far the cancer had spread, not by stage number. Among United States cases diagnosed from 2015 to 2021, 5-year relative survival was 15% for regional and 11% for distant spread. In CheckMate 743, median survival was 18.1 months with nivolumab plus ipilimumab and 14.1 months with chemotherapy. A median means half of that group lived longer and half lived less. At five years, 14% of the immunotherapy group were alive, versus 6% on chemotherapy.

Treatment for pleural mesothelioma usually combines drug therapy with care that controls symptoms. For disease that cannot be removed by surgery, the FDA has approved two first-line regimens. Those are nivolumab plus ipilimumab, two immunotherapy drugs, from October 2, 2020, and pembrolizumab with chemotherapy, from September 17, 2024. Chemotherapy with cisplatin and pemetrexed is still widely used. Some teams add bevacizumab, a drug that blocks a tumor's blood supply, off-label, since it is not FDA approved for mesothelioma. Palliative care, which eases symptoms alongside treatment, and clinical trials are worth asking about.

Surgery for pleural mesothelioma is debated, and recent evidence has moved against major operations. MARS 2 randomly assigned 335 UK patients whose disease looked removable. It tested extended pleurectomy and decortication, which removes the lung lining but keeps the lung. Median survival was 19.3 months with surgery and 24.8 months with chemotherapy alone, with about three times as many serious complications. Guidelines still support surgery for carefully chosen people with early-stage epithelioid disease at a high-volume center. Ask whether a suggested procedure aims to remove tumor or to ease breathing.

Pleural mesothelioma is not contagious, and it is usually not inherited. Most cases come from asbestos exposure rather than a gene passed down in a family. Even so, inherited changes in a gene called BAP1 are found in about 1% to 3% of mesothelioma patients overall. ASCO's 2025 pleural mesothelioma guideline includes recommendations on germline testing, which looks for inherited gene changes. Ask your loved one's team whether that testing and genetic counseling fit your family. Relatives who carry a BAP1 change can be offered lifelong monitoring.