Inverted papilloma and sarcomatoid carcinoma are both uncommon tumors of the upper aerodigestive tract, and the treatment modalities are controversial. We report a case of an 80-year-old male patient with a nasal cavity tumor. Functional endoscopic sinus surgery was performed and the pathology revealed inverted papilloma and sarcomatoid carcinoma. This combination has not previously been reported. Radiotherapy was administrated because of advanced disease, inadequate surgical margins, and the unique pathological findings. A 3-field technique was used, with a total dose to 5940 cGy. No recurrence was noted. This suggests that radiotherapy may be a useful adjuvant therapy for improving local control of this disease.