Magnetic Resonance Imaging and Histological Classification of Intracranial Meningiomas in 112 Dogs

Abstract

Background: Intracranial meningiomas are the most common primary brain tumors in dogs. Classification of meningiomas by tumor grade and subtype has not been reported, and the value of magnetic resonance imaging (MRI) characteristics for predicting tumor subtype and grade has not been investigated.Hypothesis: Canine intracranial meningiomas are a heterogenous group of tumors with differing histological subtypes and grades. Prediction of histopathological classification is possible based on MRI characteristics.Animals: One hundred and twelve dogs with a histological diagnosis of intracranial meningioma. Methods: Retrospective observational study.Results: Meningiomas were overrepresented in the Golden Retriever and Boxer breeds with no sex predilection. The incidence of specific tumor grades was 56% benign (Grade I), 43% atypical (Grade II), and 1% malignant (Grade III). Grade I histological subtypes included meningothelial (43%), transitional (40%), microcystic (8%), psammomatous (6%), and angiomatous (3%). No statistically significant (P o .05) associations were found among tumor subtype or grade and any of the MRI features studied.Conclusions and Clinical Importance: Meningiomas in dogs differ from their counterparts in humans mainly in their higher incidence of atypical (Grade II) tumors observed. MRI characteristics do not allow for prediction of meningioma subtype or grade, emphasizing the necessity of histopathology for antemortem diagnosis. The higher incidence of atypical tumors in dogs may contribute to the poorer therapeutic response in dogs with meningiomas as compared with the response in humans with meningiomas.

Histiocytic Sarcoma with Central Nervous System Involvement in Dogs: 19 Cases (2006–2012)

“…FLAIR, fluid attenuated inversion recovery.aUtilizing method of Sturges et al.,25 1 dog had 2 discrete mass lesions (olfactory and falcine).…”

Advances in Diagnostic and Treatment Modalities for Intracranial Tumors

“…Although many investigators have attempted to utilize a variety of imaging techniques to diagnose, and even grade, intracranial lesions in dogs, specificity, sensitivity, or both have been shown to be consistently suboptimal in numerous studies,12, 15, 16, 36, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56 particularly when applied to clinically relevant prospective random populations of patients. A majority of intracranial tumors in both dogs and cats are hypo‐ to isointense on T1‐weighted imaging, and hyperintense on T2‐weighted imaging.…”

“…Secondary neoplasia accounts for approximately 50% of all intracranial tumors in dogs, with the most common tumor types being hemangiosarcoma, pituitary tumors, lymphoma, metastatic carcinoma, extension of nasal neoplasms, and histiocytic sarcoma 13. The majority of primary and secondary intracranial tumors occur in older adult dogs with the majority over 5 years of age 11, 12, 13, 14, 15, 16. Median age for dogs with meningiomas, gliomas, and choroid plexus tumors is reported as 10–11 years, 8 years, and 5–6 years, respectively 9, 12, 15, 16.…”

“…The majority of primary and secondary intracranial tumors occur in older adult dogs with the majority over 5 years of age 11, 12, 13, 14, 15, 16. Median age for dogs with meningiomas, gliomas, and choroid plexus tumors is reported as 10–11 years, 8 years, and 5–6 years, respectively 9, 12, 15, 16. Primary tumors (particularly gliomas) occasionally may be seen in younger dogs 9, 17.…”

“…No sex predisposition has been reported; however it has been suggested that brain tumors generally are overrepresented in larger breeds and meningiomas are overrepresented in Golden Retrievers, Boxers, and Miniature Schnauzers. Astrocytiomas and oligodendrogliomas are highly overrepresented in specific brachycephalic breeds (Boxers, Boston Terriers, and Bulldogs), and choroid plexus tumors are overrepresented in Golden Retrievers 7, 9, 12, 15, 16, 18. Intracranial neoplasia generally is accepted to be less common in cats, although a necropsy study of approximately 4,000 cats suggested a frequency of just under 2% 19.…”