 MRI Brain, 10/7/92, revealed: a large 6x5x6cm slightly heterogeneous, mostly isointense lesion on both T1 and T2 weighted images arising from the planum sphenoidale and olfactory groove. The mass extends approximately 3.6cm superior to the planum into both frontal regions with edema in both frontal lobes. The mass extends 2.5cm inferiorly involving the ethmoid sinuses with resultant obstruction of the sphenoid and frontal sinuses.