A Flare For The Unexpected: Bone Flare As Response To Tyrosine Kinase Inhibitor Treatment In A Lung Cancer Patient New Osteoblastic Bone Lesions In A Lung Cancer Patient May Represent Bone Flare And Should Not Be Misdiagnosed As Disease Progression

We report the case of a 72-year-old female never-smoker with stage IV endothelial growth factor-receptor (EGFR) mutated lung adenocarcinoma. This patient was started on first line tyrosine kinase-inhibitor (TKI) and seemingly developed new bone metastases under this treatment. As there was a-remarkable-discrepancy between the partial response seen in the primary tumor and non-osseous-metastatic-locations, the possibility of a bone flare phenomenon was considered. In this case report, we demonstrate that new bony lesions are not always synonymous with disease progression.