title: Histologic evolution from adenocarcinoma to squamous cell carcinoma after gefitinib treatment.
abstract: We report two cases of lung cancer with histologic transformation from adenocarcinoma to squamous cell carcinoma after gefitinib treatment. Both cases involved advanced lung cancers, initially confirmed as adenocarcinomas with sensitive epidermal growth factor gene mutations. After gefitinib treatment, the second pathologic examination in each case revealed squamous cell carcinoma retaining identical mutations without newly acquired resistance mutations. The underlying mechanism may have been pluripotent tumor cells with divergent differentiation or mixed lung cancer including both adenocarcinomatous and squamous cell carcinomatous components. This report widens the spectrum of histologic evolution as a mechanism underlying the acquisition of drug resistance.
authors.affiliation: Department of Pathology, National Taiwan University Hospital and National Taiwan University College of Medicine, Taipei, Taiwan.
authors.forename: Min-Shu
authors.initials: MS
authors.lastname: Hsieh
authors.affiliation: Department of Anatomical Pathology, Far Eastern Memorial Hospital, New Taipei City, Taiwan.
authors.forename: Jie-Yang
authors.initials: JY
authors.lastname: Jhuang
authors.affiliation: Department of Pathology, National Taiwan University Hospital and National Taiwan University College of Medicine, Taipei, Taiwan.
authors.forename: Syue-Fong
authors.initials: SF
authors.lastname: Hua
authors.affiliation: Department of Anatomical Pathology, Far Eastern Memorial Hospital, New Taipei City, Taiwan. Electronic address: komet1414@gmail.com.
authors.forename: Yueh-Hung
authors.initials: YH
authors.lastname: Chou
mesh_terms: D000230:Adenocarcinoma / Q000188:drug therapy* / Q000473:pathology*; D000970:Antineoplastic Agents / Q000009:adverse effects* / Q000627:therapeutic use; D002294:Carcinoma, Squamous Cell / Q000139:chemically induced* / Q000473:pathology*; D002471:Cell Transformation, Neoplastic / Q000139:chemically induced*; D005260:Female; D000077156:Gefitinib; D006801:Humans; D008175:Lung Neoplasms / Q000139:chemically induced* / Q000188:drug therapy / Q000473:pathology*; D008875:Middle Aged; D011799:Quinazolines / Q000009:adverse effects* / Q000627:therapeutic use
chemical_list: D000970:Antineoplastic Agents; D011799:Quinazolines; D000077156:Gefitinib