Female, 55 years old, with history of metastatic nasopharyngeal cancer and concern for new brain metastasis on CT. A somewhat heterogeneously enhancing lesion is evident centered on the anteromedial left inferior temporal gyrus measuring 19 x 15 x 14 mm. On axial images, the lesion demonstrates a gyriform or stellate morphology and is ill-defined on T2-weighted images. The lesion induces moderate edema in the surrounding anterior temporal parenchyma.The lesion sits immediately above the foramen ovale. However, no clear abnormality of the V3 nerve is demonstrated. The lesion abuts the dural margin of the left Meckel's cave, but no abnormalities are seen within Meckel's cave. No lesions are detected along the cisternal segment of the left trigeminal nerve.No additional intracranial enhancing lesions are seen. There is a punctate focus of diffusion restriction within the left superior frontal gyrus. However, this occurs in the context of numerous scattered small foci of FLAIR hyperintensity within the bilateral cerebral hemispheres. No evidence of intracranial hemorrhage or any abnormal extra axial fluid collection is seen. The ventricles are normal in size and morphology. Fatty marrow replacement is evident in the clivus and upper cervical spine compatible with prior radiotherapy.
An enhancing lesion is evident centered on the anterior medial aspect of the left inferior temporal gyrus. The differential diagnosis for this lesion would certainly include metastatic disease, potentially via perineural spread given its location relative to the foramen ovale. However, no evidence of tumor involvement of the V3 nerve is seen.Some of the features of the lesion, however, are not completely typical of metastatic disease. Consequently, if a review of the radiation oncology records indicates that the anterior temporal lobes received a sufficient dose of radiation, then radiation necrosis should also be considered in the differential.A punctate focus of diffusion restriction within the left superior frontal gyrus is nonspecific. However, given the context of moderately extensive scattered small foci of signal abnormality, this may simply represent an incidental acute microvascular ischemic lesion.