Osseous metaplasia of the maxillary sinus with formation of a well-developed haversian system and bone marrow.

Osteogenesis in the maxillary sinus is a lesser known entity in otolaryngology, although it is put to good therapeutic use by maxillofacial surgeons. We present a case of postoperative osseous metaplasia in the maxillary sinus that led to the formation of mature bone with a well-developed haversian system and bone marrow. Such a finding has not been previously reported as a complication of endoscopic sinus surgery. This case highlights the importance of keeping in mind the possibility of osteogenesis within the maxillary sinus in patients who experience a recurrence of symptoms following sinus surgery.