title: Clinical and MRI findings in three dogs with polycystic meningiomas.
abstract: 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. Signs included seizures, circling, and behavior changes. 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.
authors: Department of Clinical Studies, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada. jamesf@uoguelph.ca
authors: Fiona M K
authors: FM
authors: James
authors: Ronaldo C
authors: RC
authors: da Costa
authors: Amy
authors: A
authors: Fauber
authors: Andrew S
authors: AS
authors: Peregrine
authors: Beverly
authors: B
authors: McEwen
authors: Joane M
authors: JM
authors: Parent
authors: Robert
authors: R
authors: Bergman
mesh_terms: D000818:Animals; D003560:Cysts / Q000175:diagnosis / Q000601:surgery / Q000662:veterinary*; D003937:Diagnosis, Differential; D004283:Dog Diseases / Q000175:diagnosis* / Q000601:surgery; D004285:Dogs; D017809:Fatal Outcome; D005260:Female; D008279:Magnetic Resonance Imaging / Q000662:veterinary*; D008297:Male; D008577:Meningeal Neoplasms / Q000175:diagnosis / Q000601:surgery / Q000662:veterinary*; D008579:Meningioma / Q000175:diagnosis / Q000601:surgery / Q000662:veterinary*