It is important to note that IHC, like the RT-PCR assay used in this report, is not capable of differentiating ALK fusion-positive versus full-length ALK-positive NSCLC; thus, occasional cases of IHC-positive lung cancer could possibly express full-length ALK rather than the chimeric kinase although none of our 4 cases were IHC-positive. Here, ALK is linked to non-small cell lung carcinoma.