Histopathologically, IEMC is a biomorphic tumor that comprises of undifferentiated cell mesenchymal mixed with differentiated cartilaginous tissue. Therefore, the tumor in most cases showed heterogeneous intensity in most sequences. Contrast-enhanced MRI remains the gold standard to demonstrate these lesions. However, the radiological findings are not pathognomonic for IEMCs. Calcifications that may appear incidentally on CT could be aware of the radiologist regarding IEMC. ICMEs almost are extra-axial, well-capsulated, and lobulated in shape. However, 13 cases were reported to be intra-axial (parenchymal in origin) lesions.5
TOF-MRA and SWI techniques help in the radiological diagnosis of IEMCs. The apparent dural tail is one of the most characteristic radiological features of meningioma. In our two cases, the dural tail sign wasn't net while we identified the brimmed vascular nodule without vessel dilatations on TOF-MRA. This nodule appears as a prominent blooming on SWI. This nodule is the same as those seen in vascular lesions. Although it is not pathognomonic, vasogenic peritumoral edema on FLAIR and T2WIs usually is prominent. The same features are seen in angiomatous meningiomas too. However, calcification can be distinguishable features for IEMCs. Additionally, we can recognize vascular lesions such as AVM and aneurysms by TOF-MRA.
Up-to-date, no study could differentiate IEMC from meningioma by radiological scanning studies. IEMCs are misdiagnosed as atypical meningioma,1,2 hemangiopericytoma,3 schwannomas,4 dural-based metastasis,5 gliomas, or oligodendroglioma.6 IEMCs vary from hypo- to isointense on T1-WIs with intense heterogeneous enhancement after administering a contrast substance. On T2WIs, IEMCs demonstrate iso- to hyperintensity. These lesions show an iso- to hyperintensity on MRA images that mimic arteriovenous malformations. Sometimes IEMCs demonstrate extremely hypervascular on angiographic images.3,4 Included in our two cases, the radiological features were mentioned in 30 patients. Six among them were reported to have cystic components, four were highly vascular, and three were hemorrhagic.
TOF-MRA can guide the surgeon in understanding the vascularity of the tumor, as TOF-MRA demonstrates the main vessels that passing through the tumors and is useful to identify tumor involvement with the cavernous sinus and main vascular structures. SWI technique is beneficial for detecting smaller vascular lesions that otherwise are missed by other sequences.
The craniospinal meninges are the most commonly seen location of IEMCs in CNS.1,3−6 We can divide IEMCs into dural or parenchymal. The most commonly affected region was the frontal with a dural attachment that was seen in 23 patients. Most of the reported lesions with a dural or meningeal attachment are usually supratentorial (71 patients); 49 were reported to be lateral lesions while 22 were midline lesions. Parenchymal origin was reported in 13 tumors. One of the most challenging in diagnosis the lesion is taken small biopsy or specimens from one component without pieces from the second one when obtained pieces without the cartilaginous elements.1,3−6 The lesion is generally demonstrated well-circumscribed, the rubbery firm solid, multilobulated, gray or reddish-brown colored, and almost invasive. Prominent vascularity and focal calcification are the main features of the lesion's cut surface.
The present study suffered from a few limitations, most of the early reported IEMC cases miss the important details needed to define the natural history and applied treatment, the recently reported cases miss sufficient data regarding the radiological examinations, and the pooled data were not sufficient to achieve meta-analysis review.