Left parasagittal T2W magnetic resonance image of the brain of the dog. A large, bulbous mass of heterogeneous signal intensity (open arrow) is present within the left frontal sinus. The infiltrative component is extending caudally into the diploe of the frontal and parietal bone. A broad‐based, well‐defined, extra‐axial, T2W‐hyperintense mass (white arrow) is noted within the parietal lobe ventral to the abnormal parietal bone