Meningiomas associated with brain metastases.

The authors report a series of 6 patients with simultaneous occurrence of meningioma and single brain metastasis, who underwent surgical removal with histological verification of both lesions. The site of the primary tumor was the breast in 3 cases, the ovary in one, the lung in one, and was unknown in one. Among the six patients, two had a carcinomatous metastasis accidentally found into a meningioma after histological examination of the meningiomatous mass. Two others had a brain metastasis in the cerebral parenchyma surrounding the meningioma; both lesions were removed in an one-stage operation. Finally, two patients, whose lesions were distant, first underwent removal of the brain metastasis, whereas the meningioma was excised 10 and 13 months later. The pathogenetic relationships between meningiomas and tumors of the female reproductive system are discussed. The occurrence of a metastasis into a meningioma is a rather unusual event, which has been described in 50 previously reported cases. The correct differential diagnosis between meningioma and metastasis is very important in these patients. An intracranial mass lesion occurring in patients with known malignant tumors elsewhere in the body (mainly females with breast cancers) has a small but real chance of being a meningioma.