Expression of TTF-1 and cytokeratins in primary and secondary epithelial lung tumours: correlation with histological type and grade.

AIMS: 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. METHODS AND 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.

[Nodular bronchioloalveolar carcinoma at early stage]. / Carcinome bronchioloalvéolaire nodulaire de stade IA.

INTRODUCTION: The aim of our study was to describe the main characteristics of bronchioloalveolar carcinoma (BAC) in the light of the latest WHO classification. The clinical, pathological and radiological features of 16 consecutive resected cases of early BAC (stage IA) were reviewed. METHODS: Retrospective pathology of 249 adenocarcinomas over a 32 months period. RESULTS: Computerised tomography (CT) features which supported a diagnosis of BAC included a peripheral location, irregular margins forming a star pattern, pleural tagging, ground-glass attenuation and an air bronchogram. Immunochemistry was positive in all cases for cytokeratins 7 and 19, EMA and TTF-1, but was only variably positive for ACE, P53 and MIB-1. For 14 out of 16 patients clinical outcome was favourable with no evidence to date of recurrence since surgery. Of the others, one developed extra-thoracic metastases and the other a local recurrence requiring further surgery. CONCLUSION: Recognising these characteristics of BAC is important as early diagnosis and treatment of this condition can be associated with an excellent prognosis.