Pathology of carcinoma of lung: an update on current concepts.

The incidence of mortality of lung cancer continues to increase worldwide in spite of considerable advances in diagnostic techniques and therapeutic modalities. The incidence of adenocarcinoma appears to have increased, and that of squamous cell carcinoma to have decreased, over the last few decades. The neuroendocrine tumors of the lung are emerging as a better defined group, with at least four subtypes being recognized in the spectrum ranging from typical carcinoid tumor to small cell undifferentiated carcinoma. Staging of lung tumors has also undergone major changes as new treatment modalities have become available. Pathologists are using sophisticated immunohistochemical and ultrastructural examination to categorize the tumors more accurately for appropriate therapy, follow-up, and survival studies.