Intracranial metastases from malignant pleural mesothelioma. Report of three autopsy cases and review of the literature.

We report three cases of brain metastases from malignant pleural mesothelioma that were seen at autopsy. We present a summarized review of 15 similar reports that were previously published. Our study included three aged male patients with a long occupational history of heavy asbestos exposure. In two patients, the metastases were discovered incidentally at autopsy, and there were no neurologic symptoms referred to before death. In the other patient, who had clinically occult mesothelioma, the intracranial tumor was discovered ante mortem: in this patient, the clinical features, as well as a computed tomographic scan, suggested a primary tumor of the brain. Interestingly, the histologic features of the latter case that were seen at autopsy depicted a spindle cell tumor that focally exhibited pseudopalisading, necrosis, vascular buds, which deceptively recalled a glioblastoma. All the three cases shared a basic sarcomatous pattern of malignant pleural mesothelioma in both primary and metastatic tumors. The immunohistochemical profile was consistent with such interpretation. It was concluded that metastases to the brain from malignant pleural mesothelioma, although rare, are not exceptional even if their clinical relevance is not prominent. They are seen concomitantly with high-grade tumors, and by mimicking a primary tumor on a clinical, instrumental, and histologic ground, they may occasionally represent a potential source of diagnostic pitfall.