title: [TTF-1 expression and its diagnostic application in lung carcinomas].
abstract: OBJECTIVE
  To detect the expression of thyroid transcription factor 1 (TTF-1) and study its application in the diagnosis of lung carcinomas.
  
  
  METHODS
  Of 134 specimens from lung lobectomy, 105 were primary lung carcinomas including 76 non-small cell carcinomas (NSCLCs), 28 small cell lung cancers (SCLCs) and 1 complex carcinoma (SCLC and SCC), and 29 were metastatic carcinomas. Expression of TTF-1 was detected by immunohistochemistry. The expression level of TTF-1 was graded as, +:6% to 25% of tumor cells positive, ++:26% to 50%, +++:51% to 75%, and ++++:> 76%.
  
  
  RESULTS
  The positive nuclear immunoreactivity of TTF-1 was identified in 23 of 28 SCLCs (82.1%), but none in squamous cell cancer (SCC) (P < 0.001). The positive expression rate of TTF-1 in lung adenocarcinomas (ACs) was 73.8% (31/42). There was no correlation between TTF-1 expression and ACs differentiation or ACs subtypes (P > 0.05). All but one (thyroid follicular carcinoma) metastatic ACs were TTF-1-positive. Mesenchymal component and lymphoid or inflammatory cells were consistently TTF-1-negative.
  
  
  CONCLUSIONS
  A significant difference of TTF-1 expression may assist in distinguishing SCLC from SCC, lymphoma or inflammatory lesions. Owing to its restrictive expression in lung tissue, TTF-1 might be used to differentiate primary from metastatic adenocarcinoma of the lung.
authors.affiliation: Cancer Institute (Hospital), Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing 100021, China. lindm3@yahoo.com
authors.forename: Dong-mei
authors.initials: DM
authors.lastname: Lin
authors.forename: Shuang-mei
authors.initials: SM
authors.lastname: Zou
authors.forename: Ning
authors.initials: N
authors.lastname: Lü
authors.forename: Peng
authors.initials: P
authors.lastname: Wen
authors.forename: Xiu-yun
authors.initials: XY
authors.lastname: Liu
authors.forename: Zu-gen
authors.initials: ZG
authors.lastname: He
mesh_terms: D000230:Adenocarcinoma / Q000175:diagnosis* / Q000378:metabolism; D001943:Breast Neoplasms / Q000473:pathology; D002289:Carcinoma, Non-Small-Cell Lung / Q000175:diagnosis* / Q000378:metabolism; D015179:Colorectal Neoplasms / Q000473:pathology; D003937:Diagnosis, Differential; D006801:Humans; D008175:Lung Neoplasms / Q000175:diagnosis* / Q000378:metabolism / Q000556:secondary; D009687:Nuclear Proteins / Q000096:biosynthesis*; D000074482:Thyroid Nuclear Factor 1; D014157:Transcription Factors / Q000096:biosynthesis*
chemical_list: C000614412:NKX2-1 protein, human; D009687:Nuclear Proteins; D000074482:Thyroid Nuclear Factor 1; D014157:Transcription Factors