[Metastatic Brain Tumor from Lung Adenocarcinoma Presenting a Unique Radiographic Pattern during Afatinib Treatment:A...

Epidermal growth factor receptor-tyrosine kinase inhibitors(EGFR-TKIs)are used as first-line treatment for patients with EGFR-mutated non-small cell lung cancer(NSCLC). Afatinib, a second-generation EGFR-TKI, is also effective against central nervous system(CNS)metastasis of NSCLC. However, patients treated with EGFR-TKI for many months may be at an increased risk of CNS metastasis due to the development of resistance in tumor cells to EGFR-TKI. The average period for development of resistance to EGFR-TKI is 8 to 10 months after the initiation of treatment. In the case presented herein, NSCLC showed a good clinical course in the 10 months following the initiation of afatinib;however, CNS metastasis progressed and presented unique findings on MR images. The lesions consisted of multiple cyst-like masses without gadolinium enhancement in the cerebellum and brain stem. The patient died within 2 months of the diagnosis of CNS metastasis. The resistance of tumor cells to afatinib may have occurred in the 10 months following the initiation of the treatment. Thus, CNS metastasis of NSCLC treated with afatinib may develop over a period of many months, exhibiting unique MRI findings, and deteriorate rapidly in some cases.