Lung carcinoma presenting as metastasis to intracranial meningioma: case report and review of the literature.

Tumor-to-tumor metastasis is rare. The authors report a case of a 52-year-old man with a 1-year history of a right parasaggital meningioma, whose clinical signs were consistent with enlarging meningioma. In preparation for surgery, the routine preoperative chest radiograph revealed a lung mass. Fine-needle aspiration of the mass revealed adenocarcinoma. The patient underwent surgical excision of the intracranial mass, which was thought to be a meningioma. However, pathologic examination revealed a transitional meningioma extensively infiltrated with deposits of metastatic carcinoma from the patient's primary lung tumor. Metastasis to meningioma was therefore responsible for the rapid enlargement of the long-standing meningioma, and caused the first clinical manifestation of primary lung carcinoma. Recurrent metastasis developed at the surgical site 5 weeks later, requiring surgical excision and postoperative radiation to prevent further recurrence. This is a highly unusual presentation for lung carcinoma and, to the authors' best knowledge, is the first such case reported. A review of the published literature revealed 20 other cases of lung carcinoma metastatic to meningioma, which were incidentally discovered on surgery or autopsy.