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.

Lateral ventricular meningioma (LVM) is a rare entity, accounting for 0.5%-5% of all intracranial meningiomas. This type of meningioma arises from meningothelial inclusion bodies in the tela choroidea and/or mesenchymal stroma of the choroid plexus. Although not yet fully characterized, a membranous structure is frequently observed around LVMs. This study analyzed quiescent and activated fibroblast phenotypes in LVMs with focus on the relationship between tumor growth and development of the membranous structure.
This retrospective study analyzed 9 LVM cases for which gross total removal was achieved. Expression of the ependymal cell marker (Forkhead Box J1 [FoxJ1]) was histopathologically evaluated. The distribution of quiescent and activated fibroblasts was also analyzed using anti-fibroblast-specific protein-1 (FSP1)/S100A4 antibody and anti-α-smooth muscle actin (αSMA) antibody, respectively. The control group was 5 cases with primary convexity meningioma for which Simpson grade I removal was achieved.
Small LVMs (≤30 mm) were covered by a FoxJ1-positive(+) ependymal cell monolayer; no αSMA(+) cells were detected in the tumor; and a thick membrane capsule was not observed. None of the convexity meningiomas showed FoxJ1(+) cells. Large LVMs (>30 mm) had thick membrane capsules without an ependymal cell monolayer, which resembled dura mater. The FSP1/S100A4(+) and αSM(+) cells were clearly concentrated in the peripheral area just below the thick dura mater-like membrane capsules.
This study found an association between activated fibroblasts and dura mater-like membrane capsules in LVMs. The characteristics of membranous structure in LVMs may differ depending on tumor size.

Review the data published on the subject to create a more comprehensive natural history of intraventricular meningiomas (IVMs). A Medline search up to March 2018 using \"intraventricular meningioma\" returned 98 papers. As a first selection step, we adopted the following inclusion criteria: series and case reports about IVMs, as well as papers written in other languages, but abstracts written in English were evaluated. Six hundred eighty-one tumors were evaluated from 98 papers. The majority of the tumors were located in the lateral ventricles (602-88.4%), fourth ventricle (59-8.7%), and third ventricle (20-2.9%). These tumors accounted for a mortality rate of 4.0% (25 deaths) and a recurrence rate of 5.3% (26 recurrences). The majority of the tumors were grade I (89.8%) and consisted of the following subtypes: fibrous, 39.7% (n = 171); transitional, 22.0% (n = 95); meningothelial, 18.6% (n = 80); angiomatosus, 3.2% (n = 14); psammomatous, 2.6% (n = 11); and others, 13.9% (n = 60). Forty-five patients (7.4%) presented with grade II (GII) tumors, and 17 patients (2.8%) presented with grade III (GIII) tumors. These tumors follow the histopathological distribution of meningiomas in general, with the exception of the higher prevalence of the fibrous subtype, possibly due to its embryonic origin. Recurrence and mortality were lower than in other localizations likely due to a complete surgical resection rate than in the convexity and skull base, which suggests that GTR is the gold standard for the management of IVMs.

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.