Correlation of diagnostic imaging and necropsy findings in intracranial rneningiomas in dogs and cats

Imaging assessment of meningiomas includes consideration of specific features that may provide important clues about their biological behaviour, including dural tail sign, tumour-tissue interface, the cerebrospinal cleft, and peri-tumoural brain oedema. To further elucidate the pathological basis of these key imaging features, magnetic resonance (MR) or computed tomography (CT) images were compared to corresponding macroscopic sections (frozen and plastic-embedded samples) and microscopic sections (samples taken during necropsy) of eight meningiomas from three dogs and five cats. Five meningiomas were transitional, one was meningothelial, one was papillary, and one could not be determined. Infiltrative growth patterns in four cases were associated with a poorly defined tumour-tissue interface showing a less well defined fluid cleft on diagnostic images. Expansive tumour growth in three cases was associated with a well defined tumour-tissue interface, including a well defined fluid cleft on diagnostic images of one case. In one case, pattern of growth could not be determined. Hyperostosis, brain oedema, dural tail sign, and inward buckling of grey matter were seen equally in meningiomas with infiltrative or expansive growth. Meningiomas demonstrate a range of biological behaviours, with variations in tendencies to infiltrate the bones in cats, the brain parenchyma in dogs, or the meninges in both species. In this small series of cases, imaging features did not enable differentiation of infiltrative and expansive growth patterns.