Sarcomatoid carcinomas of the upper aerodigestive tracts

Sarcomatoid carcinoma of the upper aerodigestive tract continues to be one of the most difficult diagnostic challenges for surgical pathologists. Hist ogenesis has been settled in favor of a divergent (mesenchymal) differentia tion of a carcinoma, most often a squamous cell carcinoma. Finding the carc inoma and/or its immunohistochemical marker in the metaplastic cells establ ishes the diagnosis. There are, however, lesions that can simulate sarcomat oid carcinomas to varying degrees, and in which neither a definable carcino ma nor immunohistochemical evidence of one can be found. Such lesions fall into several categories: 1. benign reactive lesions, 2. inflammatory myofib roblastic tumors, 3. sarcomas, usually low-grade, 3. atypical pseudosarcoma tous proliferation. The clinicopathologic considerations of sarcomatoid car cinomas are presented in this context and include immunohistochemical findi ngs, prognostic factors, and biologic course.