Localized Malignant Mesothelioma

Localized malignant mesothelioma is a rare form of mesothelioma that grows as a single, well-defined mass instead of spreading across the lining of the chest or abdomen. Under the microscope it looks like ordinary mesothelioma, but because it is contained it can often be removed surgically, and the outlook is usually better.

Origin

Pathologists have long separated localized tumors of the pleura from the usual diffuse, spreading mesothelioma. For many years localized tumors were assumed to be benign; the recognition that some are true malignant mesotheliomas, with the same features and stains, came in the late twentieth century, and the World Health Organization classification of pleural tumors now lists localized mesothelioma separately.

Significance in Asbestos Context

Localized malignant mesothelioma usually shows up on imaging as a single nodule or mass attached to the pleura or peritoneum, without the rind of tumor or widespread nodules typical of diffuse disease. Because it can be confused with solitary fibrous tumor, a sarcoma or lung cancer, the diagnosis rests on careful pathology with immunostains. When the tumor can be removed completely, some patients live for many years, though others later have recurrence or spread. It is still a malignant mesothelioma, and trust mesothelioma criteria generally do not distinguish localized from diffuse disease. Whether asbestos exposure is as strongly linked to the localized form as to diffuse mesothelioma has been debated, so defendants may argue the point, and the exposure history remains important.

Example Sentence

The surgeon removed a four-centimeter pleural mass, and the pathologist diagnosed localized malignant mesothelioma of epithelioid type with clear margins.

Related Terms

Malignant Mesothelioma, Pleural Mesothelioma, Solitary Fibrous Tumor, Surgical Resection, Epithelioid, Prognosis, Differential Diagnosis

Notes

• Ask your surgeon whether the tumor was completely removed and what follow-up imaging is planned.
• Keep the pathology report and the slides' location; a second review may be requested.
• Tell your doctors and lawyer about all past asbestos exposure even if you were told the tumor is unusual.