Antigenic phenotype of lung carcinomas: usual spectrum of distribution of thyroid transcription factor-1, cytokeratin 7, cytokeratin 20, and neuron specific enolase--basic immunohistochemical study of 21 cases.

Immunohistochemistry (IHC), as such, can be used in routine pathology in order to make correct diagnosis of lung carcinomas. Consequently, more detailed analyses are needed in this field in order to make a wide spectrum of unique combinations for such pulmonary neoplasms. Our aim was to apply an antibody panel, and examine and confirm its utility in the differential diagnosis of lung cancer. Twenty-one cases (both bioptic and surgical material) of diagnosed lung cancer were investigated. An immunohistochemical analysis--(RTU FLEX Immunoperoxidase system) was made using Dako monoclonal antibodies (Cytokeratin 7, CK7; Cytokeratin 20, CK20; Neuron specific enolase, NSE, Thyroid transcription factor-1, TTF1 and Leucocyte common antigen, LCA). LCA expression was not expressed in any of our cases. Most adenocarcinoma were CK7(+)--83.3% and TTF1(±)--50%. The CK20(+) expression showed a metastatic pulmonary deposit of adenocarcinoma in the lung. TTF1(+)--100%, NSE(+)--100% and CK7(-)--66.66% expression was found in most cases of SCLC. NSE(+)--100% had the highest expression in carcionoid tumour, while TTF1(+) expression was highest in SCLC. For squamous cell carcinoma (SqCC), immunostaining was negative for this antibody panel, except focal and weak expression of NSE--60%, so we did some extra IHC using CKHMW antibody, which showed the highest expression. The essential antibody panel that we have confirmed and suggest for routine basic differential diagnosis of pulmonary neoplasms is: TTF1, CK7, CK20 and NSE. Due to the high number of co-occurrunces IHC should not be performed alone, but integrated in conjunction with morphological diagnosis.