Basal ganglia hyperintensity on T1-weighted imaging of a patient with central nervous system metastasis producing carcinoembryonic antigens.

We herein report unusual basal ganglia hyperintense lesions on noncontrast T1-weighted magnetic resonance imaging in a patient with central nervous system metastasis from lung adenocarcinoma that was treated with gefitinib. T2*-weighted magnetic resonance imaging showed no hypointense lesions, thereby excluding the possibility of calcification or haemorrhage. A stereotactic brain biopsy of the left basal ganglia lesions revealed atypical cells, some of which formed a glandular lumen with a micropapillary pattern. These cells were immunopositive for markers of lung adenocarcinoma, thereby confirming the diagnosis of metastasis. We speculate that proteins, including carcinoembryonic antigens from the adenocarcinoma cells in the basal ganglia, may have contributed to the hyperintensity observed on noncontrast T1-weighted magnetic resonance imaging.