Sinonasal undifferentiated carcinoma: a distinctive and highly aggressive neoplasm.

Eleven cases of sinonasal undifferentiated carcinoma were treated between 1975 and 1986. This distinctive neoplasm involved the orbital cavity in 6 of 11 patients (55%) and the cranial cavity in 7 of 11 patients (64%) at the time of presentation. Of the eight patients (73%) who died of disease, six died within 13 months after the diagnosis. One patient has no evidence of disease 10 months after therapy, and two are alive with disease after 15 and 22 months.