A large cystic meningioma incidentally detected during general examination for breast cancer.

A 57-year-old woman who underwent needle biopsy for a subcutaneous mass in the breast was diagnosed with invasive ductal carcinoma. General examination incidentally revealed an intracranial tumor. At presentation, the patient showed memory disturbance but no focal neurological deficits. Cranial computed tomography (CT) revealed a large, hypodense cyst in the left frontotemporal region, involving a tumor with extensive hyperostotic changes in the left sphenoid and frontal bones. Magnetic resonance imaging showed that the tumor was attached to the dura mater of the pterional region and extensively enhanced, with involvement of the frontal and sphenoid bones. The less vascular tumor was removed en bloc by drilling the affected sphenoid and frontal bones as much as possible. The microscopic findings of the tumor were consistent with meningothelial meningioma with invasion into the dura mater and bone. Cystic meningioma should be considered when encountered with a dural-based cystic tumor, even in patients with cancer. In such circumstances, prompt and preferential resection may be indicated for intracranial tumors for timely initiation of the long-term treatment of cancer.