title: Warranting investigation of primary lung adenocarcinoma in patients with an extrapulmonary malignancy and lung nodules due to high frequency.
abstract: OBJECTIVE
  To distinguish primary lung adenocarcinoma (PLA) from metastatic adenocarcinoma/malignancy to optimize therapy.
  
  
  METHODS
  We investigated the utility of thyroid transcription factor 1 (TTF-1) and napsin A in distinguishing PLA from metastatic adenocarcinoma/malignancy and assessed the frequency of PLA in patients with extrapulmonary malignancy/adenocarcinoma (PLA-EPM/EPA).
  
  
  RESULTS
  TTF-1 and napsin A identified PLA in PLA-EPM/ EPA with a sensitivity of 89.4% and 93.3% and a specificity of 93.9% and 94.7%, respectively. PLA was confirmedin 47.4% of PLA-EPM and 40.2% of PLA-EPA. Overall, 38.5% of patients with PLA had EPM. The common organs for PLA-EPA were breast (35.8%), colon (13.2%), and others, whereas the common organs resulting in pulmonary metastasis were the colon (32.8%), breast (28.1%), and others. A patient with a smoking history and without EPM had a higher chance of having PLA. Multiple nodules are not a reliable indication of metastatic adenocarcinoma.
  
  
  CONCLUSIONS
  Our results firmly support the role of TTF-1 and napsin A in identifying PLA-EPM/EPA. We reason that all new lung nodules in patients with a history of EPM should be screened using these techniques due to the high frequency of PLA-EPM, which will affect treatment and prognosis of patients with EPM/EPA.
authors: Dept of Pathology, Northwestern Memorial Hospital, Feinberg School of Medicine, Northwestern University, 251 E. Huron St, Galter Pavilion 7-132F, Chicago, IL 60611; xlin@northwestern.edu.
authors: Bing
authors: B
authors: Zhu
authors: Shavari
authors: S
authors: Dalal
authors: David W
authors: DW
authors: Kamp
authors: Xiaoqi
authors: X
authors: Lin
mesh_terms: D000230:Adenocarcinoma / Q000175:diagnosis* / Q000473:pathology / Q000556:secondary; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016282:Aspartic Acid Endopeptidases / Q000378:metabolism; D014408:Biomarkers, Tumor / Q000378:metabolism; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000175:diagnosis* / Q000473:pathology / Q000556:secondary; D008297:Male; D008875:Middle Aged; D009687:Nuclear Proteins / Q000378:metabolism; D012680:Sensitivity and Specificity; D000074482:Thyroid Nuclear Factor 1; D014157:Transcription Factors / Q000378:metabolism
chemical_list: D014408:Biomarkers, Tumor; C000614412:NKX2-1 protein, human; D009687:Nuclear Proteins; D000074482:Thyroid Nuclear Factor 1; D014157:Transcription Factors; D016282:Aspartic Acid Endopeptidases; C498549:NAPSA protein, human
keywords: Extrapulmonary malignancy; Frequency; Immunohistochemistry; Metastatic malignancy; Primary lung adenocarcinoma