Biopsy of the left maxilla:  Squamous cell carcinoma

The differential for this case would be between a sinus squamous cell carcinoma or a sinonasal adenocarcinoma. The nasal cavity is uninvolved making this less likely.

Squamous cell carcinomas most commonly occur from the alveolar ridge of the maxilla.

Head and neck pathology is often very 'space oriented' in terms of the chief differentials.  It is also important to identify if the disease process is trans-spatial.