Background and Clinical Significance: Molecular testing plays a crucial role in lung cancer diagnosis and management. While single-gene tests (SGTs) remain an important diagnostic tool, developments in novel methods such as next generation sequencing (NGS) provide a more precise mutational profile and enable the targeted treatment of a larger scope of mutation-driven cancers. Case presentation: We present a case of a patient with a rare EGFR variant lung adenocarcinoma, who was misdiagnosed using a SGT. The initial treatment with immunotherapy was unsuccessful. Conclusions: The patient could have benefited if NGS had been performed instead of traditional real-time polymerase chain reaction (RT-PCR) and if adequate tyrosine kinase inhibitor treatment was initiated at the time of diagnosis.
