A case of sinonasal undifferentiated carcinoma treated without radical resection

Sinonasal undifferentiated carcinoma (SNUC) is a rare and highly aggressive neoplasm of the paranasal sinuses. SNUC is characterized by rapid expansion with high rates of recurrence and metastasis to cervical lymph nodes and distant sites. The patient was a 65-year-old woman who complained of persistant pain at the right maxilla. She had undergone endodontic therapy at the right first molar by her primary dentist. Imaging studies, including computed tomography (CT) and magnetic resonance imaging (MRI), showed a lesion occupying the right maxillary sinus and extending into the nasal cavity and ethmoid sinus. A malignant tumor of the maxillary sinus was suspected, and a biopsy was performed. The lesion was diagnosed as sinonasal undifferentiated carcinoma.The patient was treated with chemoradiation therapy. After 4 cycles of chemoradiation therapy, CT and MRI showed shrinkage of the lesion and changes consistent with necrosis. Histological examination of a repeat biopsy specimen after the 4 cycles of chemoradiation did not contain tumor cells. 2 more cycles of chemoradiation therapy were added.Six months after the initial diagnosis, CT finding suggested residual tumor in the ethmoid sinus. We performed another biopsy and the histopathological analysis was negative for tumor. The patient has been followed for 33 months since completing chemoradiation therapy, and there has not been any further evidence of disease.