Recently, clinical, occupational, and pathological features of these tumors have been summarized for a large group of patients. Usually a large thoracoscopic or open biopsy is required to evaluate the histologic pattern and to use for special studies. Cytologic examination or tissue from a cutting needle biopsy can sometimes yield a diagnosis, but Cope needle biopsies are usually inadequate. If malignancy is a consideration at the time of biopsy, some tissue should be put into glutaraldehyde fixative in the operating room for electron microscopy. In a newly-proposed TNM system, T1 to T3 tumors are potentially resectable.
Tumor cells are distinct from the benign stroma.
These patterns resemble carcinomas. Spindle-celled tumors are composed of sheets of elongate cells without an identifiable benign stroma. Tumors with both epithelial and sarcomatous components are termed dimorphic tumors. The pathologist must first decide whether or not malignancy is present. Special stains are of no proven value in this regard.