Echinoderm microtubule-associated protein-like 4- anaplastic lymphoma kinase EML4-ALK gene rearrangements are present in around 5% of non-small cell lung carcinoma (NSCLC) patients . In the majority of cases, they are adenocarcinomas . It is noteworthy that, in some series, more than 17% of lung cancer patients who never smoked have this genomic alteration . Currently, analysis for the EML4-ALK status is mainly performed by immunohistochemistry (IHC) and confirmed by FISH analysis from tissue biopsies . This status can also be detected on cytological samples by immunochemistry (ICC) and/or by FISH analysis . However, molecular biology methods are also used for this genomic alteration detection in tissues or cells, in particular by next generation sequencing (NGS) . The presence of an EML4-ALK rearrangement leads to targeted treatment . Despite a frequent early response, relapse and progression is systematically noted, which can lead to a change in targeted therapy . In most cases, this tumor progression is linked to the emergence of EML4-ALK mutations .