Expression of TTF-1 and cytokeratins in primary and secondary epithelial lung tumours: correlation with histological type and grade.
OBJECTIVE
To assess cytokeratin (CK) and thyroid transcription factor (TTF)-1 expression in primary epithelial lung tumours by comparison with non-pulmonary carcinomas and to correlate it with their histological type and grade.


RESULTS
Immunohistochemistry using antibodies against CKs 5/6, 7, 19, 20 and TTF-1 was applied to 165 primary and 37 secondary epithelial lung tumours. CK5/6 is a sensitive and specific marker of lung squamous carcinomas being positive in 100% of cases. CK7 is a common marker of primary lung adenocarcinomas (100% of cases) but with a lower specificity since it is also observed in other primary lung carcinomas (70% of large-cell neuroendocrine carcinomas, 40% of large-cell carcinomas, 23% of squamous carcinomas) but also in 27% of non-pulmonary adenocarcinomas. Addition of an anti-CK20 may be useful to prove or disprove the pulmonary origin of an adenocarcinoma when there is a history of colon cancer. CK19 is ubiquitous but a predominant or exclusive 'dot-like' pattern is very suggestive of high-grade neuroendocrine carcinoma. TTF-1 is a very sensitive and specific marker to document the pulmonary origin of an adenocarcinoma if a thyroid origin is excluded. Its expression in neuroendocrine lung tumours depends on the tumour grade.


CONCLUSIONS
Immunohistochemical expression of CKs and TTF-1 may be correlated with histological type and grade of lung primary epithelial tumours and may allow them to be distinguished from non-pulmonary carcinomas.
Service d'Anatomie et Cytologie Pathologiques, Hôpital Purpan, Toulouse, France.
V
V
Jerome Marson
J
J
Mazieres
O
O
Groussard
O
O
Garcia
J
J
Berjaud
M
M
Dahan
P
P
Carles
G
G
Daste
D000230:Adenocarcinoma / Q000378:metabolism* / Q000556:secondary; D000368:Aged; D014408:Biomarkers, Tumor / Q000378:metabolism*; D002294:Carcinoma, Squamous Cell / Q000378:metabolism* / Q000556:secondary; D005260:Female; D006801:Humans; D007124:Immunoenzyme Techniques; D007633:Keratins / Q000378:metabolism*; D008175:Lung Neoplasms / Q000378:metabolism* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009687:Nuclear Proteins / Q000378:metabolism*; D000074482:Thyroid Nuclear Factor 1; D014157:Transcription Factors / Q000378:metabolism*
D014408:Biomarkers, Tumor; C000614412:NKX2-1 protein, human; D009687:Nuclear Proteins; D000074482:Thyroid Nuclear Factor 1; D014157:Transcription Factors; D007633:Keratins