Mesenchymal Tumors of the Lung

Primary mesenchymal neoplasms of the lung are rare tumors. These include both benign and malignant lesions. With the exception of pulmonary chondroid hamartoma which represents the most common benign lung tumor, sarcomas generally predominate, although overall primary pulmonary sarcomas still only account for less than 0.5% of all primary lung cancers (Guccion and Rosen, Cancer 30:836-847, 1972). Since the lung is often the site of metastatic disease from extrathoracic sarcomas, a diagnosis of primary pulmonary sarcoma always requires exclusion of a primary tumor elsewhere. Furthermore, primary mesenchymal tumors of lung origin must be differentiated from sarcomatoid lung tumors of non-mesenchymal origin, such as carcinomas or mesotheliomas with spindle cell features. The morphological and immunohistochemical characteristics and molecular profiles of primary mesenchymal lung tumors closely resemble those of their soft tissue analogues, and the spectrum of entities recognized to occur in the lung is continually increasing. Pathological examination is the gold standard in the diagnosis of primary mesenchymal neoplasms of the lung, as the clinical and radiological manifestations are non-specific and often bear a resemblance to those of bronchogenic carcinoma.