Radiographic appearance of leptomeningeal disease in patients with EGFR-mutated non-small-cell lung carcinoma treated with tyrosine kinase inhibitors: a case series.

EGFR is frequently mutated in non-small-cell lung carcinomas (NSCLCs). Clinically available tyrosine kinase inhibitors (TKIs) are effective in treating EGFR-mutant NSCLC. In this case series, we present five patients with TKI-treated EGFR-mutated NSCLC who developed leptomeningeal disease (LMD) lacking characteristic imaging findings. All five patients received TKIs prior to development of cytology-confirmed LMD. Clinical signs of LMD preceded radiographic evidence by 2-12 months. T790M, the most common resistance mutation to first-generation EGFR inhibitors, was identified in four cases. These cases illustrate that in patients with EGFR-mutant NSCLC, TKIs may effectively control LMD, creating a lag between onset of symptoms and observation of radiographic findings.