The thyroid transcription factor 1 (TTF-1) is a highly sensitive and specific marker of adenocarcinomas of pulmonary origin in differential diagnosis of solitary pulmonary nodules. Positivity of TTF-1 as a marker of primary pulmonary tumor could have a very high impact on surgical treatment strategy. From known protocols we developed the method of immunohistochemical investigation of intraoperative bioptic samples from frozen section lasting about 15 minutes. During last year, we applied this method on 30 cases of intraoperative bioptic samples. All investigated cases were verified by immunohistochemical examination from formalin-fixed and paraffin-embedded definite tissue samples. With the exception of two samples in which the result was inconclusive from both frozen and fixed tissue, all other samples revealed the same result. Our experience demonstrates that intraoperative immunohistochemical investigation of TTF-1 in proper consequences could be a very useful tool for routine practice.

        Key words: thyroid transcription factor 1 (TTF-1) – intraoperative biopsy – immunohistochemistry – lung adenocarcinoma