Localized benign pleural mesothelioma arising in a radiation field.

Localized benign pleural mesothelioma is a rare neoplasm representing less than 5% of all pleural tumors. Unlike the malignant diffuse pleural mesothelioma, there is no evidence of a relationship to asbestos exposure. Essentially, the cause of localized benign pleural mesotheliomas remains obscure. We propose that one mechanism of the development of this tumor is prior ionizing radiation to the tumor field. Ionizing radiation is a well-known human oncogen and leads to an increased incidence of benign tumors as well. A 65-year-old woman had a localized benign pleural mesothelioma of her left upper chest 22 years following adjuvant radiation therapy to the left breast and axillary region for a breast carcinoma.