Presentation
Severe headaches in a patient known for breast carcinoma on follow-up.
Patient Data
Rounded relatively symmetrical capsulo-lenticular masses isointense to the cortical grey matter on T1, FLAIR and T2 with restricted diffusion on DWI/ADC. Surrounding vasogenic edema of a low signal on DWI and facilitated diffusion on ADC. No hemorrhagic component on the GE sequence. The postcontrast sequence shows a vivid homogeneous enhancement.
The MR spectroscopy shows an intratumoral choline peak, lipid peak (tumor necrosis) and depleted NAA.
Two other small enhancing nodules are noted in the right temporal and left frontal lobes at the grey-white matter junction..
Trichilemmal cysts are noted.
Case Discussion
The MRI features in a patient known for breast carcinoma are highly suggestive of brain metastases. The symmetrical location in the capsulo-lenticular regions is rarely seen (as in this case).
CNS lymphoma may be considered in the differential diagnosis, however some MRI findings are against this diagnosis:
the location of the frontal and temporal lesions at the grey-white matter junction
the surrounding edema is usually more prominent in metastases compared to CNS lymphoma
the MR spectroscopy in this case is almost typical of metastases, while in CNS lymphoma, we usually observe a reversed choline/creatinine peak +/- sometimes a lactate peak