Precise Diagnosis of Histological Type of Lung Carcinoma: The First Step in Personalized Therapy

This chapter is a combination of personal experience of a pulmonary pathologist and available references in the diagnosis of non-small cell lung cancer (NSCLC) types. The morphological appearance of poorly differentiated lung carcinoma is not characteristic, so immunohistochemical staining is used for further differentiation. In order to save tumor tissue from paraffin blocks, the most rational way is to use only two antibodies, p40 for squamous cell carcinoma and TTF-1 for adenocarcinoma of the lung, and if necessary or if cancer growth is organoid, also one of two neuroendocrine markers (CD56 or Synaptophysin) can be used. If there is enough tumor tissue in the paraffin block to confirm the diagnosis, NapsinA, p63, Cytokeratin5/6 or Cytokeratin5 can be used. It should be kept in mind that no antibody is highly specific for one histological type of carcinoma or its origin and if the immunohistochemical finding is unspecific, it should be concluded that this is “not otherwise specified” (NOS) carcinoma. The rest of tissue must be preserved for current and future molecular testing and predictive immunohistochemical staining for the purpose of personalized NSCLC therapy