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Hellenic Archives of Pathology, Volume 22, Issues 1-3, 2008, 33-40
Diagnostic utility of thyroid transcription factor (TTF1) expression in pleural effusion specimens
Nepka C.1, Karadana M.1, Barbanis S.1, Makris D.2, Karasavvidou F.1, Gourgoulianis K.2, Koukoulis G.1
1Pathology Dept and
2Respiratory Dept of University Hospital of Larisa
Aim: The aim of this study was to examine the clinical utility of thyroid transcription factor (TTF1) expression in pleural effusions with positive cytologic diagnosis. We studied the usefulness of the immunostain in supporting the diagnosis of adenocaricnoma of pulmonary origin as well as its utility in the detection of single neoplastic cells in the evaluation of metastatic disease in pleural effusions. Finally, we studied the applicability of the immunostain in cytologic material by comparative analysis of the immunocytochemical expression of TTF1, both quantitatively and qualitatively, on cell block material and on the corresponding direct smears prepared from the sediment of the pleural effusion.
Materials and Methods: We studied 39 cases of positive pleural effusions. In 14 the primary site was unknown at the time of cytologic diagnosis while in 25 cases the clinical question was related to the presence of metastatic disease in pleural cavity from patients with a known primary neoplasm. Immunocytochemical stains were performed on cell block material as well as on direct smears form the pellet of pleural effusion.
Results: From the 14 effusions with unknown primary lesion, 7 were positive for TTF1. This information in relation with other clinical and laboratory findings supported the diagnosis of adenocarcinoma of pulmonary origin, except for one case of a primary lung cancer where the immunostain was negative. From the 25 effusions with a known primary site cytology was positive in 2 lung small cell carcinomas and 7 lung adenocarcinomas all of them positive for TTF1 except for one adenocarcinoma. The immunostain was helpful in two cases were the neoplastic cells were few and dispersed. In addition, in one case with known primary breast cancer, TTF1 was positive indicating a second primary tumor in the lung.
Conclusions: TTF1 immunostain is a very useful marker in the diagnostic approach of positive pleural effusions. It can reliably support the diagnosis of a primary lesion of pulmonary origin. It is also helpful in the detection of single, dispersed neoplastic cells in the pleural cavity. Finally, TTF1 is applicable to cytologic smears and the expression of the stain in smears gives comparable results with cell block material.
Key words: TTF1, pleural effusion, immunocytochemistry.
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