Histological classification and TNM staging of lung cancerHistologische Klassifikation und TNM-Einteilung der Lungenkarzinome

BACKGROUND: The diagnosis of lung cancer comprises a variety of different histological types and clinical situations. METHODS: Review of the recent literature. RESULTS: Generally, primary lung carcinomas are classified according to the best differentiated component following WHO criteria and are graded according to the worst differentiated component. Non-small cell lung cancers (NSCLC) are all those lung carcinomas without evidence of small cell lung cancer. Depending on tumour size, more than 50% of lung carcinomas contain more than one of the histological types of the main representatives of NSCLC. However, minor portions are not included in the classification. Main representatives, with a prevalence of more than 90%, are squamous cell carcinoma, small cell carcinoma, adenocarcinoma and large cell carcinoma. About 80% of lung carcinomas are assigned to the group of non-small cell lung cancers (NSCLC), 20% are small cell lung cancers (SCLC). Of NSCLC, the group of adenocarcinomas is steadily increasing and currently amounts to 40%, squamous cell carcinomas also amount to 40%, the rest are large cell carcinomas and other rare tumour types. The pathologist establishes the diagnosis of a clinically suspected malignant tumour from biopsy material, especially considering dignity, differentiation between primary lung carcinoma and metastasis, classification and tumour type with particularly meticulous differentiation between small cell carcinoma and NSCLC. Intraoperative frozen section directly determines further surgical procedure. Pathological examination of the resected specimen provides current pTNM classification and thereby determines further prognosis and therapy. The newly revised WHO histopathologic classification of lung cancer, international TNM Staging System for Lung Cancer as well as stage groupings are presented. CONCLUSIONS: Stage and histopathologic type determine appropriate treatment and prognosis of lung cancer.