[Malignant lung tumors--histomorphological classification, immunohistological techniques and prognostic factors].

Histological typing of lung tumors is based on the new WHO-IASLC classification of lung and pleural tumors published in 1999. Based on histological growth pattern, the major light microscopic categories of lung carcinomas are squamous cell carcinoma, small cell carcinoma, adenocarcinoma and large cell carcinoma. The further subclassification within the main categories resembles the high degree of lung tumor heterogeneity. Immunohistochemistry may detect differentiation that cannot be seen by routine light microscopy on small bioptically obtained specimens. Evaluation of the proliferation index of tumor cells, hormonal receptors, oncogenes and tumor-suppressor genes is possible. Oncogenes, tumor-suppressor genes, angiogenetical factors as well as single cell dissemination of tumor cells in lymph nodes are discussed as possible prognostic factors.