What is Mesothelioma?

10 questions to ask your doctor this week

The first oncology visit after a mesothelioma diagnosis is a lot to absorb. Walking in with a written list of questions makes a real difference. Here are ten prioritized questions, written for someone new to the diagnosis.

1. What type of mesothelioma do I have (pleural, peritoneal, pericardial) and what cell type (epithelioid, sarcomatoid, biphasic)?
2. What stage is my cancer, and what does that mean for treatment options?
3. Should I get a second opinion at a mesothelioma specialty center, and which would you recommend?
4. What are my realistic treatment goals — cure, life extension, symptom management, or a combination?
5. What are all the treatment options you’re considering (surgery, chemotherapy, radiation, immunotherapy, clinical trials)?
6. Should I have biomarker or genetic testing that might change my treatment options?
7. What clinical trials might be available for someone with my diagnosis?
8. What side effects should I expect, and how will we manage them?
9. Who on my care team can I call between appointments, and for what kinds of questions?
10. How often will we reassess, and what scans or tests will we use?

Write these down. Bring them to every appointment. Even if your doctor covers most of them without prompting, you’ll know you covered the ground. For more on what to expect in the weeks after diagnosis, see our Treatment page. The American Cancer Society also publishes a general questions-to-ask guide that’s worth reviewing.

Understanding your diagnosis: location, cell type, and stage

Your mesothelioma diagnosis is actually several pieces of information, each of which shapes the treatment conversation. Here’s what those terms mean in plain language.

Location — where the cancer started

• Pleural — in the lining around the lungs. The most common form, about 75% of cases.
• Peritoneal — in the lining around the abdomen. Most of the remaining cases.
• Pericardial — in the lining around the heart. Rare.

Cell type — how the cancer cells look under a microscope

• Epithelioid — the most common type and generally the most responsive to treatment.
• Sarcomatoid — less common, generally more aggressive, with fewer standard treatment options.
• Biphasic — a mix of both cell types; outcomes depend on the ratio.

Stage — how far the cancer has spread

Doctors use a staging system (I through IV for pleural mesothelioma) based on tumor size, lymph node involvement, and whether the cancer has spread beyond the original site. Stage influences whether surgery is an option, which drugs make sense, and what the typical course looks like. Ask your doctor to explain your specific staging and cell type. Those two pieces determine much of what follows.

The NCI Mesothelioma Treatment (Patient PDQ) has detailed information on staging systems and how they affect treatment planning. For the next step, see our Treatment page.

How mesothelioma is actually diagnosed

Most mesothelioma diagnoses take several steps. Understanding the process helps you know where you are and what’s next.

1. Imaging. Usually a chest X-ray first, followed by a CT scan. A PET/CT may follow to look for spread. An MRI can add detail about chest-wall or diaphragm involvement.
2. Fluid analysis. If there’s fluid around the lungs (pleural effusion), your doctor may draw a sample (thoracentesis) and send it to the lab. Fluid alone usually cannot confirm mesothelioma, but can help rule out other causes.
3. Biopsy. A tissue sample is the only way to confirm mesothelioma. This is usually done through VATS (video-assisted thoracoscopic surgery) or a needle biopsy. The sample goes to pathology.
4. Pathology review. A specialist pathologist examines the tissue and runs immunohistochemical stains to identify the specific cell type. This is where your epithelioid, sarcomatoid, or biphasic designation comes from.
5. Staging. Once the diagnosis is confirmed, additional imaging and sometimes further biopsies determine the extent of disease and assign a stage.

If your diagnosis came quickly through only some of these steps, or if the cell type is unclear, ask for a second opinion — ideally from a mesothelioma specialty center. Mesothelioma is rare and initial misdiagnosis is common. A second pathology review is routine and often valuable. The NCI maintains a directory of NCI-designated cancer centers, many of which have dedicated mesothelioma programs.

Red flags vs. worries that can wait

Between appointments, every new symptom can feel like an emergency. Here’s how to think about which are urgent and which can wait for the next scheduled visit.

Call your care team today (or go to the ER):

• Sudden or severe chest pain or pressure, especially with sweating, nausea, or left-arm pain (treat as possible cardiac emergency — go to the ER)
• New or worsening shortness of breath, especially at rest
• Fever above 100.4°F, chills, or signs of infection
• Coughing up blood
• Severe new headache, vision changes, or confusion
• Swelling, warmth, or pain in one leg (possible blood clot)
• Sudden severe belly pain, persistent vomiting, or inability to keep fluids down

Bring up at the next scheduled visit:

• Gradual fatigue changes
• Mild appetite changes
• Bowel or bladder pattern changes (if gradual)
• Sleep trouble
• Mood or anxiety changes
• Mild, slowly worsening cough

Keep a simple daily symptom journal: date, what you noticed, how bad it was on a 0-10 scale. Patterns matter more than individual bad days. For mental health support, see our Support page, which includes information on crisis resources. If you’re in the United States and having thoughts of self-harm, call or text 988 for free, confidential crisis support.