Mesothelioma tumors are classified by cell type (also called histology) based on microscopic examination. Understanding your cell type helps doctors develop the most effective treatment plan and provides important information about expected disease behavior.
Cell Type Comparison
Epithelioid Mesothelioma
The most common and most treatable cell type. Epithelioid cells grow more slowly and respond better to treatment than other types.
Characteristics
- Uniform, cube-shaped cells
- Well-defined cell boundaries
- Slower growth rate
- Less likely to metastasize quickly
- Best response to chemotherapy
Treatment Response
Epithelioid mesothelioma responds best to standard treatments including surgery, chemotherapy, and immunotherapy. Patients are often candidates for aggressive multimodal therapy.
Median survival: 14-19 months
Sarcomatoid Mesothelioma
The rarest and most aggressive cell type. Sarcomatoid cells grow quickly and are resistant to many treatments.
Characteristics
- Spindle-shaped, elongated cells
- Irregular cell patterns
- Rapid growth rate
- High tendency to spread
- Most resistant to treatment
Treatment Response
Sarcomatoid mesothelioma is challenging to treat. Surgery is rarely recommended. Chemotherapy and immunotherapy may slow progression but have lower response rates.
Median survival: 4-6 months
Biphasic Mesothelioma
Contains both epithelioid and sarcomatoid cells. Prognosis depends on the ratio of each cell type present.
Characteristics
- Mix of epithelioid and sarcomatoid cells
- Must contain at least 10% of each type
- Behavior varies by dominant cell type
- Prognosis depends on cell ratio
- Treatment response varies
Treatment Response
Treatment approach depends on which cell type is dominant. A higher percentage of epithelioid cells generally means better treatment response and prognosis.
Median survival: 8-12 months
Rare Cell Types
Several rare cell type variants exist, including desmoplastic, lymphohistiocytoid, and well-differentiated papillary mesothelioma. These uncommon variants may have different prognostic implications.
Learn more about rare cell types →How Cell Type Is Determined
Cell type is identified through tissue biopsy. A pathologist examines the tumor cells under a microscope and may use special staining techniques (immunohistochemistry) to accurately classify the cells. This process is essential because:
- Different cell types respond differently to treatments
- Cell type affects eligibility for certain clinical trials
- Prognosis varies significantly by cell type
- Surgical decisions may depend on cell type
Cell Type and Treatment Decisions
Doctors consider cell type when developing treatment plans:
- Epithelioid tumors — Often candidates for aggressive treatment including surgery and multimodal therapy
- Sarcomatoid tumors — May focus on palliative care, chemotherapy, or clinical trials for new treatments
- Biphasic tumors — Treatment approach depends on the dominant cell type and overall health
Importance of Second Opinions
Because cell type significantly affects treatment options, obtaining a second opinion on your pathology results from a mesothelioma specialist is often recommended. Specialized pathologists with mesothelioma experience are more likely to accurately identify cell type and any subtypes that may affect prognosis.