[Morphological and molecular pathology of lung cancer]

Lung carcinoma is the most frequent cause of cancer death in Germany. It is characterized by a considerable morphological complexity that has been reduced by clinicians to the distinction between small cell (SCLC) and non-small cell carcinoma (NSCLC). Underpinned by the possibilities of more differentiated tumor therapy, the classification of lung cancer has undergone a re-evaluation, some essential developments of which are summarized in this article. SCLC and NSCLC do not only differ in gene expression and genetic alterations but also in the ploidy level: SCLC is typically hypodiploid, NSCLC often hyperdiploid/near-triploid. Immunohistochemical analysis is meanwhile standard and includes in particular the markers p63, TTF-1, CK5/6, CK7, CD56/NCAM, synaptophysin, chromogranin and Ki67. A new interdisciplinary classification of adenocarcinoma differentiates between preinvasive, minimally invasive and invasive lesions. Lending new weight to the predominantly histological growth patterns it includes information on molecular genetic alterations such as EGFR mutations.