Sinonasal undifferentiated carcinoma of the maxillary sinus.

We describe the case of a 43-year-old man who was referred to our dental school"s acute care clinic with pain and swelling of presumed dental origin in the left maxillary quadrant. Radiographic examination revealed extensive dental decay and periodontal disease. On questioning, the patient admitted to paresthesia of recent onset. Paresthesia associated with pain or swelling of the jaws is an ominous sign that should alert the clinician to the possibility of an underlying aggressive neoplasm. In this case, biopsy of the lesion confirmed that the patient had a rare malignant tumour of maxillary sinus origin, a sinonasal undifferentiated carcinoma.