Intraventricular meningiomas are thought to arise from meningothelial inclusion bodies located in the tela choroidea and/or mesenchymal stroma of the choroid plexus 1) 2) 3).
Intraventricular meningiomas show similar characteristics to those found in the extra-axial space. Their cells of origin are the same; however, extra-axial meningiomas are derived from the arachnoid cap cells, naturally occurring near venous sinuses and dural edges. Intraventricular meningiomas originate from the choroid plexus stroma and arise at the tela choroidea. Here, arachnoid cells are found secondary to the embryologic origin of the choroid plexus. Most meningiomas are considered to be benign World Health Organization (WHO) grade I, slow-growing lesions. However, some may progress to atypical or anaplastic histopathological types 4).
In general, these meningiomas are most commonly fibrous meningiomas 5).
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); angiomatous, 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 6).
Intraventricular meningiomas are present usually due to mass effect, either by direct compression of the adjacent brain or from obstruction to normal CSF drainage with resultant hydrocephalus.