Abstract
The distinction between separate primary lung carcinomas (SPLCs) and intrapulmonary metastases (IPMs) is crucial to accurate cancer staging. Histopathology-based classification cannot always determine the relatedness of multiple tumors taken from the lung. Recently, next-generation sequencing (NGS) has been used for biomarker determination, but it also has the potential to inform clonality determination among multiple tumors. Here we present a patient with three lung tumors, each diagnosed as adenocarcinoma by histopathology with a differential diagnosis of SPLC versus IPM. We pursued molecular profiling by NGS, which revealed three unique mutational patterns ruling out the possibility of clonal relatedness among the cancers. Our case supports the utility of NGS in supplementing histopathological methods to distinguish between SPLCs and IPMs and to guide treatment decisions.