Histology comment:

I think it fits best with sinonasal undifferentiated carcinoma. The major alternative diagnosis would be small cell carcinoma, and I thought that the nuclear morphology, with many cells having prominent nucleoli and some have at least moderate amounts of cytoplasm, was very much against that diagnosis. The morphology and immunohistochemical staining pattern are entirely consistent with sinonasal undifferentiated carcinoma. I did not think the morphology was correct for lymphoepithelial carcinoma.