The ethmomaxillary sinus: A rare anatomical variant.

Bilateral ethmomaxillary sinuses (EMS) were discovered during a computed tomography scan of a 30-year-old male patient who presented with intermittent nasal congestion, after having undergone prior functional endoscopic sinus surgery for chronic rhinosinusitis. The EMS is a rare paranasal sinus variant, and whether this anomaly is congenital or developmental remains to be decided. Five walls form the boundaries of the EMS. The lateral wall of this structure is usually formed by the posterolateral wall of the maxillary sinus, and the current case is the first to describe an independent lateral wall of the EMS.