For several decades, primary lung cancers were consistently dichotomously classified for treatment and research purposes into small-cell lung carcinomas (SCLCs) and non-small-cell lung carcinomas (NSCLCs), based on an oversimplified approach that is now clearly outmoded. The new paradigm recognizes that lung cancers are a large and extremely heterogeneous family of malignant neoplasms, with over 50 different histological variants included in the 4th (2004) revision of the World Health Organization typing system, the most widely used lung cancer classification scheme ("WHO-2004"). These variants are increasingly appreciated as having different genetic, biological, and clinical properties, including prognoses and responses to treatment regimens, and therefore, that correct and consistent histological classification of lung cancers are necessary to validate and implement optimum management strategies. About 1% of lung cancers are sarcomas, germ<unk>  tumors, and hematopoietic tumors, while 99% of lung cancers are carcinoma. Carcinomas are tumors composed of transformed, abnormal<unk> s with epithelial tissue architecture and/or molecular characteristics, and which derive from embryonic endoderm. Eight major taxa of lung carcinomas are recognized within the WHO-2004 classification: # Small-cell carcinoma # Squamous<unk>  carcinoma # Adenocarcinoma # Large-cell carcinoma # Adenosquamous carcinoma # Sarcomatoid carcinoma # Carcinoid # Salivary gland-like carcinoma The subclassification of GCCL among these major taxa has undergone significant changes in recent decades. Under the 2nd revision (1981) of the WHO classification, it was considered a subtype of large-cell carcinoma. In the 3rd (1999) revision, it was placed within a taxon called "Carcinomas with Pleomorphic, Sarcomatoid, or Sarcomatous Elements", along with pleomorphic carcinoma, spindle<unk>  carcinoma, carcinosarcoma, and pulmonary blastoma, which are (arguably) related variants. While the 4th revision ("WHO-2004") retained the same grouping of lesions as the 3rd revision, the name of the major taxon was shortened to "sarcomatoid carcinomas". The current rules for classifying lung cancers under WHO-2004, while useful and improved, remain to some extent fairly complex, ambiguous, arbitrary, and incomplete. Although it is fairly common for mixed tumors that are seen to contain malignant<unk> <unk> s to be called<unk> -cell carcinomas", accurate classification of a pulmonary tumor as a GCCL requires that the entire tumor consists only of malignant<unk> <unk> s. Therefore, complete sampling of the entire tumor — obtained via a surgical resection — is absolutely necessary for a definitive diagnosis of GCCL to be made.
Giant-cell carcinoma of the lung
Mucinous cystadenocarcinoma of the lung
Sarcomatoid carcinoma of the lung
Epithelial-myoepithelial carcinoma of the lung
Pulmonary sclerosing pneumocytoma
Adenocarcinoma of the lung
Salivary gland–like carcinoma of the lung
Mesothelioma