Overview
Some mesothelioma tumors have unusual cell patterns that pathologists rarely see. Getting the diagnosis right matters—some rare types respond better to treatment than common ones.
Characteristics
- Uncommon microscopic appearances
- May be difficult to diagnose correctly
- Some variants have better prognoses
- Others are more aggressive than typical types
- Require specialized pathology expertise
- Often initially misdiagnosed
Subtypes
Desmoplastic
Dense fibrous tissue with few tumor cells; often mistaken for benign conditions
Lymphohistiocytoid
Contains many inflammatory cells; may have better prognosis
Small cell
Resembles small cell lung cancer; aggressive behavior
Deciduoid
Cells resemble pregnancy-related tissue; rare, prognosis unclear
Adenomatoid
Gland-like appearance; generally benign variant
Well-differentiated papillary
Slow-growing; often has excellent prognosis
Diagnosis
Accurate cell type identification is critical for treatment planning. Diagnosis typically involves:
- Requires expert pathologist review
- Multiple immunohistochemistry markers needed
- Genetic testing may assist diagnosis
- Second opinion strongly recommended
- May be confused with other cancers or benign conditions
Treatment Options
Treatment for rare mesothelioma cell types may include:
- Treatment based on predominant cell characteristics
- Some variants respond well to standard therapy
- Others may require different approaches
- Clinical trials important for rare variants
- Treatment individualized based on behavior
Prognosis
Prognosis for rare cell types varies significantly. Well-differentiated papillary mesothelioma, for example, often has an excellent prognosis with survival of many years. In contrast, small cell variants tend to be aggressive. Due to rarity, large studies are limited, and individual outcomes depend on the specific variant and treatment response.
Learn about mesothelioma prognosis factors →Getting a Second Opinion
Because cell type significantly affects treatment options and prognosis, obtaining a second opinion on your pathology results from a mesothelioma specialist is often recommended. Pathologists with mesothelioma experience are more likely to accurately identify cell type, subtypes, and any unusual features that may affect your treatment plan.