This article reviews current concepts in pathologic classification of lung cancer based on 1999 World Health Organization (WHO)/International Association for the Study of Lung Cancer (IASLC) classification. Preinvasive lesions including squamous dysplasia/carcinoma in situ, atypical adenomatous hyperplasia and diffuse idiopathic pulmonary neuroendocrine cell hyperplasia are discussed in addition to current concepts of bronchioloalveolar carcinoma and neuroendocrine tumors.
