Anterior Skull Base Masses

Giant Tumors Involving the Anterior Skull Base

• Magnetic resonance images demonstrate multiple masses of the anterior skull base with varying intrinsic signal properties, morphology, and pattern of enhancement.

• Case A features a broad-based, avidly enhancing extraaxial mass centered at the floor of the anterior cranial fossa along the fovea ethmoidalis and extending posteriorly along the planum sphenoidale. Mass effect and superior displacement of the overlying gyrus recti and orbitofrontal cortex are present. Also note the posterior displacement of the anterior cerebral arteries without evidence of vascular encasement.

• Case B features a large, heterogenous, enhancing mass that appears to be centered along the inferior margin of the cribriform plate, with the bulk of the tumor projecting into the right nasal cavity. Bowing and chronic remodeling of the adjacent bony structures and sinuses are present. Concomitant chronic obstructive changes of the right maxillary sinus are seen, resulting from obstruction of the right ostiomeatal complex.

• Case C features an irregular, heterogeneously enhancing mass. Infiltration and direct destructive intracranial extension is present through the cribriform plate, with associated aggressive-appearing extension through the left lateral orbital wall. Complex, irregular internal enhancement is seen, with cystic change along the margins and fluid-fluid levels indicative of intratumoral hemorrhage/necrosis. Cerebrospinal fluid clefting of the intracranial component of this lesion confirms the extraaxial morphology, with marked mass effect and vasogenic edema. Chronic obstruction and infiltration of the right frontal sinus are present.

• Case D features an abnormal, enhancing, intraaxial mass lesion centered within the orbitofrontal parenchyma. Relatively heterogenous intrinsic enhancement is present. Examination of the remainder of the brain parenchyma reveals multifocality, with additional areas of abnormal parenchymal enhancement.