Intracranial meningioma in a pet rat: MRI findings

We herein report the magnetic resonance imaging (MRI) findings in a brain meningioma in a pet rat (Rattus norvegicus domestica). A 1.5-year-old pet rat was referred for depression, ataxia, tremors and bilateral nystagmus; a brain MRI was elected suspecting an intracranial neoplasia. The study was performed with a 0.25 T scanner. The MRI revealed a well-defined oval mass with a heterogeneous appearance, hyperintense in T1 and T2, and with extra-axial localisation and severe brain compression, the mass appeared strongly and diffusely contrast-enhancing. Euthanasia was elected, with the necropsy confirming the presence of a voluminous extra-axial mass. Histologically, a well-differentiated, benign meningotheliomatous meningioma was diagnosed, with the histochemical stains allowing one to exclude a granular cell tumour. To the best of our knowledge, this is the first report of MRI investigations on a pet rat intracranial meningioma.