Thyroid transcription factor-1 is commonly used as a basic marker for lung carcinomas, with a reported sensitivity range for lung adenocarcinomas between 75 and 80% (Lau et al, 2002; Jagirdar, 2008) and 92% according to our own study (see Table 3): However, TTF-1 can also be found in other lung tumour entities such as SCLC, large-cell neuroendocrine carcinomas and carcinoids (Folpe et al, 1999). Here, TTF1 is linked to lung carcinoma.