Sarcomatoid Carcinoma of the Lung: Histologic Criteria and Common Lesions in the Differential Diagnosis

Abstract

Abstract Context.—Sarcomatoid carcinoma of the lung is a subset of poorly differentiated non–small cell lung cancers that are diagnostically challenging because they are uncommon, may reveal little of their parent cell of origin, and overlap morphologically with other anaplastic epithelioid and spindle cell tumors that can be primary in, or metastatic to, the lung and pleura. Objective.—To review the current histologic classification and diagnostic criteria that identify the 5 subtypes of sarcomatoid carcinoma of the lung and to discuss the most common tumors in the differential diagnosis. Design.—Published classification systems from the World Health Organization and pertinent peer-reviewed articles indexed in PubMed (National Library of Medicine) form the basis of this review. Conclusions.—Identification of sarcomatoid carcinoma of the lung requires knowledge of specific histologic criteria that define the 5 subgroups, targeted immunohistochemical studies, and correlation with chest imaging to assess distribution of disease and to avoid misdiagnosis.