Sarcomatoid neoplasms of the respiratory tract.

Sarcomatoid carcinomas (SCAs) of the respiratory tract are uncommon neoplasms of adults, most of whom are men in late middle-age who have a long history of tobacco usage. These tumors may be observed in the paranasal sinuses, nose, naso-oropharynx, larynx, trachea, central bronchi, or peripheral lung parenchyma. They may assume a polypoid configuration, with projection into luminal spaces, or show an infiltrative growth pattern like that of typical high-grade carcinoma. Histologically, both biphasic and monophasic variants of SCAs are recognized. The former include tumors with foci of overt carcinoma admixed with areas of divergent differentiation into "committed" mesenchymal tissues, such lesions have usually been termed "carcinosarcomas" in the past. On the other hand, monophasic SCAs lack obviously epithelial foci on light microscopy. Ultrastructural and immunohistological studies support the notion that SCA represents a continuum that embraces carcinosarcomas and spindle-cell carcinomas, all of which are basically epithelial neoplasms. Tumor behavior is site-dependent; SCAs of the nose, sinuses, pharynx, and lungs usually pursue an aggressive course, whereas histologically similar lesions in the larynx are usually found at an earlier stage and, therefore, are associated with a better prognosis.