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Angiomatous meningiomas are rare histological subtype of meningiomas and account for only 2.1% of all meningiomas 1,3.
The epidemiology and clinical presentation of these tumors do not clearly deviate from that of more common histological variants of meningiomas and is thus not repeated here.
Unfortunately, the main differential for an angiomatous meningioma is a hemangiopericytoma, which used to be considered a variant of meningioma and went by the annoyingly similar name of "angioblastic meningioma".
Angiomatous meningiomas, as their name suggests, demonstrate abundant blood vessels (greater than 50% of a whole tumor) within a tumor with areas of classic meningothelial differentiation 1. They are considered WHO grade I tumors and cellular atypia and anaplasia is not present 3.
The appearance of angiomatous meningiomas on CT is similar to that of more typical meningothelial and fibrous subtypes, appearing as slightly hyperdense to adjacent brain parenchyma and exhibiting vivid contrast enhancement 1.
On MRI angiomatous meningiomas can be difficult to distinguish from microcystic meningiomas and chordoid meningiomas other than the presence of often prominent flow voids. They frequently have obvious dural tails and not infrequently demonstrate some cystic change 1.
Typically they exhibit the following signal characteristics 1:
- T1: hypointense compared to grey matter
- T1 C+: vivid enhancement
- hyperintense compared to grey matter
- peritumoral edema very common (75-100%) 2
- prominent flow voids
- DWI / ADC: facilitated diffusion
- MRA: in some cases, feeding vessels may be visible 1
Treatment and prognosis
Although surgery is the mainstay of treatment, as is the case for other variants, the presence of such abundant blood supply can make surgery more difficult. As such pre-operative embolization may be of benefit.
Other entities to be considered predominantly are extra-axial masses with high T2 signal and masses with prominent blood supply. These include:
solitary fibrous tumor of the dura
- can appear very similar
- less likely to have a dural tail 4
- more likely to enhance heterogeneously 4
- more likely to have microlobulation / irregular contour 4
- perhaps counterintuitively ADC values are higher than in angiomatous meningiomas 4
- bone and brain invasion more common
- somewhat more common in younger males (vs. older females)
- other meningioma variants which usually do not have as prominent flow voids
- intra-axial (albeit peripheral) usually in the posterior fossa
- typically cyst with an enhancing mural nodule