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Types of Mesothelioma
Location, Cell Subtypes, Symptoms, Staging and Treatment Differences
Mesothelioma is classified by the site where the cancer originates and by the microscopic appearance of the tumor cells. These classifications address distinct questions and are not interchangeable.
The four main anatomical sites are the pleura (around the lungs), peritoneum (abdomen), pericardium (around the heart), and tunica vaginalis (surrounding the testis). Pleural mesothelioma is the most common, followed by peritoneal. Pericardial and tunica vaginalis mesotheliomas are rare. Histologically, mesothelioma is classified as epithelioid, biphasic, or sarcomatoid.
Anatomical site largely determines the pattern of presentation and the applicable staging framework, while both anatomical site and histology can influence treatment decisions and prognosis. Evidence from pleural mesothelioma should not be assumed to apply to other sites.
This article provides general educational information and is not a substitute for diagnosis or treatment advice from a qualified healthcare professional.
On This Page
- Types at a Glance
- What Are the Types of Mesothelioma?
- How Mesothelioma Is Classified
- Pleural Mesothelioma
- Peritoneal Mesothelioma
- Pericardial Mesothelioma
- Tunica Vaginalis Mesothelioma
- Does Asbestos Affect All Types the Same Way?
- Histologic Subtypes
- How Symptoms Differ
- How Diagnosis Differs
- How Staging Differs
- How Treatment Differs
- How Prognosis Differs
- Genetics and Germline Testing
- Why Specialist Care Matters
- Questions to Ask Your Medical Team
- Frequently Asked Questions
- References
Mesothelioma Types at a Glance
| Type | Where it starts | Relative frequency | Typical presentation | Staging approach | Treatment evidence |
|---|---|---|---|---|---|
| Pleural | Pleura surrounding the lungs | Most common (>8 in 10) | Breathlessness, chest pain, pleural effusion | Site-specific AJCC/TNM system | Largest evidence base |
| Peritoneal | Peritoneum lining the abdomen | Second most common | Abdominal distension/pain, ascites, early satiety | No equivalent AJCC Stage I–IV system | CRS-HIPEC for selected patients; systemic evidence limited |
| Pericardial | Pericardium surrounding the heart | Rare | Effusion, breathlessness, chest discomfort; sometimes tamponade | No validated pericardial-specific AJCC Stage I–IV system | No randomized site-specific standard |
| Tunica vaginalis | Tunica vaginalis surrounding the testis | Very rare | Hydrocele, scrotal swelling or mass | No widely validated site-specific Stage I–IV system | Mainly retrospective/case-series evidence |
What Are the Types of Mesothelioma?
Mesothelioma begins in mesothelial tissue, a thin lining that covers or surrounds several body cavities and organs. The anatomical name of the tumor is based on the site where it originated, not simply where disease is later found.
This distinction matters because cancer from another organ can spread to a serosal surface. For example, metastatic cancer involving the pleura or pericardium is not the same as primary pleural or pericardial mesothelioma. Determining the true site of origin relies on imaging, pathology, and the overall clinical context.
How Mesothelioma Is Classified
Mesothelioma is classified by anatomical site and histologic subtype. For example, a patient may have epithelioid pleural mesothelioma or biphasic pleural mesothelioma. The anatomical term describes the tumor’s origin, while the histologic term describes its microscopic appearance.
Classification by anatomical site
The four principal anatomical sites are pleural, peritoneal, pericardial, and tunica vaginalis. These sites differ in frequency, presentation, staging systems, surgical options, and available treatment evidence.
Classification by histology
Current pathology guidance recognizes three main histologic categories: epithelioid, biphasic, and sarcomatoid. Pathologists use morphology, immunohistochemistry, and, when necessary, molecular tests, rather than relying on a single marker.
Pleural Mesothelioma
Pleural mesothelioma develops in the pleura, the membrane surrounding the lungs and lining the chest cavity. It is by far the most common anatomical type, accounting for more than 8 in 10 mesotheliomas according to the American Cancer Society.
Symptoms usually reflect pleural and chest involvement rather than a unique mesothelioma pattern. Shortness of breath, chest pain, cough, fatigue, and pleural effusion may occur, but these symptoms are not specific to mesothelioma.
Pleural mesothelioma has the most developed evidence base among mesothelioma sites. It has a site-specific TNM staging system, and major randomized trials have evaluated systemic therapies specifically in unresectable pleural disease. In the United States, nivolumab plus ipilimumab is FDA-approved as first-line treatment for adults with unresectable pleural mesothelioma, while pembrolizumab with pemetrexed and platinum chemotherapy is FDA-approved as first-line treatment for unresectable advanced or metastatic pleural mesothelioma. These approvals should not be presented as automatically applying to peritoneal, pericardial, or tunica vaginalis mesothelioma.
Surgery may be considered for selected patients, typically after multidisciplinary review at experienced centers. Suitability for surgery depends on tumor extent, histology, cardiopulmonary fitness, treatment goals, and team expertise. Read our dedicated guide to pleural mesothelioma for more detail.
Peritoneal Mesothelioma
Peritoneal mesothelioma begins in the peritoneum, the membrane lining the abdominal cavity and covering many abdominal organs. It is the second most common anatomical type and accounts for most mesotheliomas arising outside the pleura.
Presentations may include abdominal swelling, pain or pressure, ascites, early satiety, bowel changes, fatigue, or unintended weight loss. These nonspecific findings typically require imaging and tissue diagnosis if mesothelioma is suspected.
Peritoneal disease should not be staged using the pleural AJCC Stage I–IV system. Specialists assess disease distribution, tumor burden, histology, resectability, patient fitness, and other clinical factors. Research staging systems exist but are not interchangeable with the pleural TNM framework.
For selected patients, cytoreductive surgery with hyperthermic intraperitoneal chemotherapy (CRS-HIPEC) may be considered at experienced centers. Recent consensus highlights the need for individualized assessment and notes limited evidence on optimal systemic therapy timing. Clinical trial enrollment is encouraged when appropriate. Read our dedicated guide to peritoneal mesothelioma.
Pericardial Mesothelioma
Primary pericardial mesothelioma arises from the pericardium surrounding the heart. It is exceptionally uncommon, and the published evidence consists largely of case reports, small series, and retrospective reviews rather than randomized trials.
Patients may present with pericardial effusion, shortness of breath, chest discomfort, constrictive physiology, or cardiac tamponade. These findings are more often caused by other conditions, making diagnosis challenging. Imaging can detect pericardial abnormalities, but tissue sampling and expert pathology are often required.
There is no validated pericardial-specific AJCC Stage I–IV system. Clinicians instead evaluate the actual extent of pericardial involvement, invasion of cardiac or mediastinal structures, lymph-node or distant disease, and whether meaningful surgery is technically feasible.
No randomized trial has established a pericardial-specific treatment standard. Management may include urgent treatment of effusion or tamponade, surgery for selected patients, systemic therapy, radiation in certain cases, clinical trials, and supportive care. Evidence from pleural trials may inform specialist discussions but does not directly prove benefit in primary pericardial mesothelioma. Read our dedicated guide to pericardial mesothelioma.
Mesothelioma of the Tunica Vaginalis
Mesothelioma of the tunica vaginalis is a very rare tumor arising from the serosal lining around the testis. While “testicular mesothelioma” is common in patient materials, the anatomically precise term is mesothelioma of the tunica vaginalis, as it does not originate from testicular tissue itself.
Presentations may include hydrocele, scrotal swelling, a paratesticular mass, or findings initially mistaken for an inguinal hernia. Diagnosis is often unexpected and may only be confirmed after surgery and pathological examination.
Evidence is limited. A systematic review of published case-series data identified 275 patients and noted the absence of established treatment recommendations. Reported management has generally centered on surgery, with additional treatment individualized according to pathologic and clinical findings. Because the disease is so rare, treatment decisions are best discussed with specialists familiar with mesothelioma and genitourinary oncology.
Does Asbestos Affect All Mesothelioma Types in the Same Way?
No. The strength and quantity of evidence differ by anatomical site.
Asbestos exposure is the best-established environmental risk factor for pleural mesothelioma and is also associated with peritoneal mesothelioma. However, a recognized exposure history is not required for diagnosis, and exposure history alone is insufficient for diagnosis. Our asbestos exposure guide covers this topic in more detail.
For pericardial and tunica vaginalis mesothelioma, the evidence base is much smaller because these tumors are so rare. An Italian case-control study found associations between occupational asbestos exposure and these rare sites, but the number of cases was limited compared with pleural disease. The strength of evidence should therefore not be presented as equivalent across all anatomical sites.
Histologic Subtypes of Mesothelioma
Histology refers to the microscopic appearance of the tumor. It is distinct from anatomical site, though both influence treatment decisions and prognosis.
Epithelioid mesothelioma
Epithelioid is the most common histologic subtype. Tumors may display various morphologic patterns, and current guidance recommends grading epithelioid pleural mesothelioma using recognized histologic features. In general, epithelioid mesothelioma is associated with a more favorable prognosis than sarcomatoid mesothelioma, but histology is only one factor in prognosis.
Sarcomatoid mesothelioma
Sarcomatoid mesothelioma consists mainly of spindle-shaped malignant mesothelial cells. It is generally more aggressive and can be difficult to diagnose, as other spindle-cell tumors may appear similar.
Biphasic mesothelioma
Biphasic mesothelioma contains both epithelioid and sarcomatoid components. Adequate tissue sampling is essential, as limited biopsies may not capture the full tumor composition.
How pathology confirms mesothelioma
Pathologists do not diagnose mesothelioma from one immunohistochemical stain. Current consensus guidance recommends integrating morphology with a panel of markers that support mesothelial differentiation and markers that help exclude competing diagnoses.
Ancillary studies such as BAP1 or MTAP immunohistochemistry and CDKN2A deletion testing can be useful in selected settings, but their performance and interpretation depend on the anatomical site and diagnostic question.
How Symptoms Differ by Mesothelioma Type
| Anatomical type | Symptoms or findings that may occur | Important caution |
|---|---|---|
| Pleural | Shortness of breath, chest pain, cough, pleural effusion, fatigue | These findings overlap with many pulmonary and cardiac conditions. |
| Peritoneal | Abdominal distension or pain, ascites, early satiety, bowel changes, fatigue | These findings overlap with many gastrointestinal, hepatic, gynecologic, and other abdominal disorders. |
| Pericardial | Pericardial effusion, breathlessness, chest discomfort, constrictive physiology, tamponade | Pericardial disease is far more often caused by conditions other than primary pericardial mesothelioma. |
| Tunica vaginalis | Hydrocele, scrotal swelling or mass, sometimes hernia-like presentation | These are common presentations of many benign conditions; diagnosis usually requires pathology. |
Symptoms alone cannot determine the type of mesothelioma. Persistent or unexplained symptoms require medical evaluation, and the diagnostic approach depends on the affected site. Our symptoms guide covers this in more detail.
How Diagnosis Differs by Type
Diagnosis typically involves clinical history, imaging, and pathology, but the most effective tests vary by site. Pleural disease is evaluated with chest CT and thoracic procedures; peritoneal disease may require abdominal imaging and tissue sampling; pericardial disease often needs echocardiography and cardiac imaging; tunica vaginalis mesothelioma may be found during evaluation of a hydrocele or scrotal mass. Our diagnosis guide and imaging tests guide cover these approaches in more detail.
Fluid cytology may be helpful in certain cases, but its sensitivity varies by site and specimen. If mesothelioma is still suspected, adequate tissue sampling and expert pathology review are important. Imaging alone cannot determine histologic subtype. Our tests and biopsy guide covers these procedures in more detail.
How Staging Differs by Mesothelioma Type
Mesothelioma is not staged identically at every anatomical site.
Pleural mesothelioma has a dedicated TNM staging system developed through the International Association for the Study of Lung Cancer and incorporated into modern staging practice. The staging framework evaluates the primary pleural tumor, regional lymph nodes, and distant metastasis. Our mesothelioma stages guide covers this system in more detail.
Peritoneal, pericardial, and tunica vaginalis mesotheliomas do not have a widely validated AJCC Stage I–IV system like pleural mesothelioma. Clinicians use site-specific measures of disease extent, resectability, tumor burden, nodal or distant spread, and other prognostic factors.
Staging information for pleural mesothelioma should not be assumed to apply to peritoneal, pericardial, or tunica vaginalis mesothelioma.
How Treatment Differs by Mesothelioma Type
| Type | Treatment approach in broad terms | Evidence limitation |
|---|---|---|
| Pleural | Systemic therapy has randomized-trial support; surgery and radiation may have roles in selected patients within multidisciplinary care. | Randomized trial evidence is strongest for unresectable pleural disease; treatment still depends on individual factors. |
| Peritoneal | CRS-HIPEC may be considered for selected patients; systemic therapy and trials may also be considered. | Evidence is less robust than for pleural disease, and optimal systemic-therapy sequencing remains uncertain. |
| Pericardial | Manage hemodynamic complications first when present; selected surgery, systemic therapy, radiation, trials, and supportive care may be considered. | No randomized pericardial-specific treatment standard has been established. |
| Tunica vaginalis | Published management is usually surgery-centered, with additional therapy individualized. | No established evidence-based treatment pathway has been validated in large prospective trials. |
The key principle is that mesothelioma treatment is not a single universal approach. Anatomical site, histology, disease extent, symptoms, prior treatment, patient fitness, and care goals all influence treatment. Clinical trial eligibility may also differ by site, as some studies enroll only pleural mesothelioma. Our treatment guide covers the full range of approaches used across mesothelioma types.
How Prognosis Differs by Type
Prognosis varies widely and cannot be summarized with a single figure for all mesotheliomas. Anatomical site, histology, disease extent, treatment options, overall health, treatment era, and patient selection all affect outcomes.
Pleural mesothelioma has the largest trial and registry datasets. Peritoneal outcomes may differ significantly in selected patients at specialized centers, especially in surgical series. Pericardial and tunica vaginalis data are limited, making direct comparisons unreliable.
Survival figures from one anatomical type should not be applied to another, and group statistics should not be presented as individual life expectancy.
Our complete guide to Mesothelioma Prognosis and Survival covers these concepts in more detail.
Genetics and Germline Testing
Inherited cancer susceptibility affects a minority of patients with mesothelioma. Pathogenic germline variants can involve BAP1 and other cancer-predisposition genes; BAP1 is the best-characterized hereditary association in mesothelioma.
The 2025 ASCO pleural mesothelioma guideline states that all patients with mesothelioma should be offered germline testing. It also recommends that all patients who are offered testing be offered pretest genetic counseling with a qualified health professional. The genes evaluated may be informed by the patient’s personal and family history and other actionable cancer-risk genes.
Germline testing looks for inherited variants that can be present throughout the body, whereas somatic testing evaluates changes identified in tumor cells. Results should be interpreted with qualified genetic counseling.
Why Specialist Care Matters
Mesothelioma is uncommon, and pericardial and tunica vaginalis mesotheliomas are especially rare. Diagnosis and treatment may require collaboration among specialists in oncology, surgery, radiology, pathology, pulmonology, gastroenterology, cardiology, urology, genetics, and palliative care, depending on the anatomical site.
Specialist review is especially valuable when diagnosis is uncertain, major surgery is considered, disease arises outside the pleura, or clinical trial participation is possible.
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Questions to Ask Your Medical Team
- Where did my mesothelioma originate?
- What histologic subtype was identified?
- Has my pathology been reviewed by a pathologist experienced in mesothelioma?
- Which staging or disease-extent system is appropriate for my anatomical type?
- Which treatment evidence applies directly to my type of mesothelioma, and which recommendations are extrapolated from pleural disease?
- Should my case be reviewed by a multidisciplinary mesothelioma team?
- Should I be offered germline testing, and what pretest genetic counseling is available?
- Are there clinical trials that accept patients with my specific anatomical type?
Frequently Asked Questions
What are the four main types of mesothelioma?
The four main anatomical types are pleural, peritoneal, pericardial, and mesothelioma of the tunica vaginalis. They are named for the site where the tumor originates.
What is the most common type of mesothelioma?
Pleural mesothelioma is by far the most common and accounts for more than 8 in 10 mesotheliomas, according to the American Cancer Society.
What is the rarest type of mesothelioma?
Pericardial and tunica vaginalis mesotheliomas are both very rare. Because of their rarity, precise rankings depend on the dataset, so it is more accurate to describe both as rare sites rather than assign a fixed ranking.
Are epithelioid and sarcomatoid separate anatomical types?
No. Epithelioid, sarcomatoid, and biphasic are histologic subtypes. Pleural, peritoneal, pericardial, and tunica vaginalis are anatomical sites.
Are all mesothelioma types staged the same way?
No. Pleural mesothelioma has a dedicated TNM staging system. Other anatomical sites do not have an equivalent widely validated AJCC Stage I–IV system, so the pleural staging framework should not simply be applied to them.
Do all mesothelioma types receive the same treatment?
No. Treatment depends strongly on anatomical site, histology, disease extent, symptoms, resectability, previous treatment, and overall health. Some randomized treatment evidence and FDA approvals are specifically for pleural mesothelioma.
Does asbestos cause every type of mesothelioma?
Asbestos is the best-established environmental risk factor for pleural mesothelioma. It is also associated with other sites, but the amount and strength of evidence are not identical across all anatomical types. Rare-site evidence is much more limited.
Should people with mesothelioma have genetic testing?
ASCO recommends that all patients with mesothelioma be offered germline testing and that patients offered testing also be offered pretest genetic counseling with a qualified health professional.
References
- American Cancer Society. Mesothelioma. Last revised February 3, 2026. Accessed August 2026.
- Kindler HL, Ismaila N, Bazhenova L, et al. Treatment of Pleural Mesothelioma: ASCO Guideline Update. Journal of Clinical Oncology. 2025;43(8):1006–1038. doi:10.1200/JCO-24-02425.
- Husain AN, Chapel DB, Attanoos R, et al. Guidelines for Pathologic Diagnosis of Mesothelioma: 2023 Update of the Consensus Statement From the International Mesothelioma Interest Group. Archives of Pathology & Laboratory Medicine. 2024;148(11):1251–1271. doi:10.5858/arpa.2023-0304-RA.
- Wolf AS, Eisele M, Giroux DJ, et al. The International Association for the Study of Lung Cancer Pleural Mesothelioma Staging Project: Expanded Database to Inform Revisions in the Ninth Edition of the TNM Classification of Pleural Mesothelioma. Journal of Thoracic Oncology. 2024;19(8):1242–1252. doi:10.1016/j.jtho.2024.01.018.
- Brown LM, Wilkins SG, Bansal VV, et al. Consensus Guideline for the Management of Peritoneal Mesothelioma. Annals of Surgical Oncology. 2026;33(6):5125–5141. doi:10.1245/s10434-025-17358-x.
- McGehee E, Gerber DE, Reisch J, Dowell JE. Treatment and Outcomes of Primary Pericardial Mesothelioma: A Contemporary Review of 103 Published Cases. Clinical Lung Cancer. 2019;20(2):e152–e157. doi:10.1016/j.cllc.2018.11.008.
- Marinaccio A, Consonni D, Mensi C, et al. Association Between Asbestos Exposure and Pericardial and Tunica Vaginalis Testis Malignant Mesothelioma: A Case-Control Study and Epidemiological Remarks. Scandinavian Journal of Work, Environment & Health. 2020;46(6):609–617. doi:10.5271/sjweh.3895.
- Grogg JB, Fronzaroli JN, Oliveira P, et al. Clinicopathological Characteristics and Outcomes in Men With Mesothelioma of the Tunica Vaginalis Testis: Analysis of Published Case-Series Data. Journal of Cancer Research and Clinical Oncology. 2021;147(9):2671–2679. doi:10.1007/s00432-021-03533-6.
- Baas P, Scherpereel A, Nowak AK, et al. First-line Nivolumab Plus Ipilimumab in Unresectable Malignant Pleural Mesothelioma (CheckMate 743): A Multicentre, Randomized, Open-label, Phase 3 Trial. The Lancet. 2021;397(10272):375–386. doi:10.1016/S0140-6736(20)32714-8.
- Chu Q, Perrone F, Greillier L, et al. Pembrolizumab Plus Chemotherapy Versus Chemotherapy in Untreated Advanced Pleural Mesothelioma: A Phase 3 Randomized Controlled Trial. The Lancet. 2023;402(10419):2295–2306. doi:10.1016/S0140-6736(23)01613-6.
- U.S. Food and Drug Administration. FDA Approves Pembrolizumab With Chemotherapy for Unresectable Advanced or Metastatic Malignant Pleural Mesothelioma. September 17, 2024.
- National Cancer Institute. Nivolumab. Updated May 8, 2025. Accessed August 2026.
Medical Disclaimer: This article offers general medical information and is not a substitute for advice from your oncology team. See our full medical disclaimer.
