EGFR中罕见的外显子18-21突变包括除致敏L858R替换和外显子19缺失外的所有EGFR突变，以及抗突变T790M。Rare exon 18-21 mutations in EGFR consist of all EGFR mutations excluding sensitizing L858R substitutions and exon 19 deletions, as well as resistance mutation T790M.
