One spayed female Labrador retriever and two castrated male golden retrievers were evaluated for chronic (i.e., ranging from 3 wk to 24 wk) neurologic signs localizable to the prosencephalon.
MRI demonstrated extra-axial, contrast-enhancing, multiloculated, fluid-filled, cyst-like lesions with a mass effect, causing compression and displacement of brain parenchyma.
Differential diagnoses included cystic neoplasm, abscess or other infectious cyst (e.g., alveolar hydatid cyst), or fluid-filled anomaly (e.g., arachnoid cyst).
The cyst-like lesions were attached to the rostral falx cerebri in all cases. In addition, case 2 had a second polycystic mass at the caudal diencephalon.
Surgical biopsy (case 3 with a single, rostral tumor via transfrontal craniectomy) and postmortem histology (in cases 1 and 2) confirmed polycystic meningiomas.
Tumor types were transitional (cases 1 and 3) and fibrous (case 2), with positive immunohistochemical staining for vimentin.
Case 3 was also positive for E-cadherin, s100, and CD34.
In all cases, staining was predominantly negative for glial fibrillary acid protein and pancytokeratins, supporting a diagnosis of meningioma.
This report describes the first cases of polycystic meningiomas in dogs.
Polycystic meningiomas are a rare, but important, addition to the differential diagnoses for intracranial cyst-like lesions, significantly affecting planning for surgical resection and other therapeutic interventions.
Source: Fiona M. K. James, Ronaldo C. da Costa, Amy Fauber, Andrew S. Peregrine, Beverly McEwen, Joane M. Parent, Robert Bergman (2012): Clinical and MRI Findings in Three Dogs with Polycystic Meningiomas. In: Published online before print July 27, 2012, doi: 10.5326/JAAHA-MS-5774
Journal of the American Animal Hospital Association Sep/Oct 2012 jaaha.5774
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