EML4 and small cell lung carcinoma: According to previous reports, IHC was positive for ALK protein without EML4-ALK fusion mutation in SCLC patients [15], and previous reports also suggest that IHC should not be used as the only method to determine EML4-ALK fusion mutation, but it should be determined by a combination of multiple tests, and in addition, the genetic test can provide more personalized and targeted treatments.