A 72-year-old female patient presented with a single-sided stuffy nose, headache, purulent running nose and
purulent cough for several years. A large posterior maxilloethmoidal cell was noted behind the maxillary sinuses
bilaterally and found to drain into the superior nasal meatus. She underwent unilateral functional endoscopic sinus surgery
with right ethmoidectomy and middle meatal antrostomy. The postoperative course was uneventful.
A well developed posterior ethmoidal cell extends to superolateral portion of sphenoid sinus is called as Onodi's cell. A
well developed posterior ethmoidal cell extends to the maxillary sinus more than 50% of the antrum space as the case we
presented. We have tentatively named this unique finding a posterior “maxilloethmoidal cell.”