Ventricular meningiomas are neoplastic cells originating from the ependymal lining of the central canal of the spinal cord and the ventricles of the brain. These tumorigenic cells predominantly manifest in the fourth ventricle, followed by the spinal cord. Most intraparenchymal ventricular meningiomas are located within the brain tissue, exhibiting a higher degree of malignancy compared to their intracerebroventricular counterparts. While intracranial dissemination and metastasis to the spinal cord can occur, extra-neurologic metastasis is an exceedingly rare phenomenon that lacks a clear elucidation regarding its underlying mechanism. The authors presented a case of supratentorial brain parenchymal type ventricular meningioma surgical treatment in a young female patient, occurring two years after the development of multiple metastases in both lungs, pleura, and mediastinum. This may be attributed to the high malignancy degree and strong invasiveness of this lesion, as well as its proximity to the dura mater and venous sinus. The craniotomy provided an opportunity for tumor cells to invade the adjacent venous sinus, leading to dissemination through the blood system. Additionally, postoperative radiation and chemotherapy were administered to inhibit tumor angiogenesis; however, these treatments also increased the likelihood of tumor cell invasion into neighboring brain tissues and distant metastasis.

We report 13 patients with third ventricular meningiomas (TVM) and discuss the clinical, radiological, pathological and surgical features, as well as follow-up of these tumors. TVM are rare intracranial tumors, and because of this, there are few reports in the literature. Of 11,600 intracranial meningiomas that were surgically treated and pathologically confirmed at Beijing Tian Tan Hospital over a period of 10 years (2003-2013), 13 TVM were selected for a retrospective review. We recorded the clinical, radiological, pathological, and surgical data and statistically analyzed the preoperative, postoperative and 6 month postoperative Karnofsky performance scale (KPS) scores. TVM represented 0.11% of intracranial meningiomas. Radiologically, TVM were divided into three groups: anterior (n=3), posterior (n=3), and entire third ventricle (n=7). Three patients (23.1%) were misdiagnosed preoperatively. Total removal was achieved in 61.5% (8/13) of patients, and subtotal resection was achieved in 38.5% (5/13). Pathologically, the tumors were World Health Organization (WHO) Grade I in 11 patients (84.6%) and WHO Grade II in two (15.6%). There were no statistically significant differences in the preoperative, postoperative, or 6 month postoperative KPS scores (F=0.814; p=0.401). TVM without dural attachments are rare neoplasms that should be differentiated from choroid plexus papilloma, craniopharyngioma, and pineocytoma. Surgery is the optimal treatment and may result in a favorable prognosis, and understanding of the radiological subtype can help with the choice of surgical approach.