Meningioma

Case example

The first candle is lit

A 12 year-old, female-spayed Golden Retriever was presented for multiple episodes of seizures.

MRI findings

An oval, mixed and to the majority T2w hyper- and isointense (isointense to the gray-matter), as well as T1w isointense lesion is within the caudal aspect of the right olfactory and caudally adjacent within the ipsilateral frontal lobe (image 1) Multiple small circular and amorphous T2w hyper- and T2w FLAIR hypointense (isointense to the cerebrospinal fluid signal) areas are within this mass (image set 2). It causes a mild mass effect with left-ward deviation of the falx cerebri and markedly, homogeneously contrast enhances with multifocal “dural-tail” signs, characterized by thin, tapering and markedly contrast enhancing extensions from the mass along the leptomeninges (image set 3 and image 4). Mild to moderate perilesional edema is characterized by surrounding T2 and T2 FLAIR hyperintense regions extending along the white-matter (image 5).

Conclusions

  • Extra-axial right olfactory and frontal lobe lesion with mild to moderate perilesional edema and dural-tail signs is most consistent with a meningioma.

Learning points

  • Typical MRI characteristics are: T2w hyper- and T1w isointensity, as well as intense and homogenous pattern of T1w contrast enhancement with sharp contours. However, depending on the histological type imaging findings can vary and a classification system allowing for a reliable tumor categorization is not yet available.
  • The “Dural-tail sign” is not pathognomonic and can present in 23 to 82% of cases.
  • Histological evaluation of focal areas of T2w hyperintensity indicated foci of low cellularity with intratumoral necrosis or haemmorhage.

More information

  • »Magnetic Resonance Imaging and Histological Classification of Intracranial Meningiomas in 112 Dogs«
    — B.K. Sturges et al., JVIM 2008;3(22):586-595
  • »Canine and feline intracranial meningiomas: an updated review«
    — L. Motta et al., Vet J. 2012;192(2):153-65
  • »Magnetic resonance imaging diagnosis of brain tumors in dogs«
    — T. Bentley, Vet J. 2015;205(2):204-16

Images courtesy of Animal Health Partners, Canada.

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