abnormal paranasal sinus morphology abnormal sphenoid sinus morphology MP:0002248 MPheno.ontology abnormal sphenoidal sinus morphology any structural anomaly of the paired evaginations of the mucous membrane of the nasal cavity into the air space located within the sphenoid bone, and which communicates with the upper posterior nasal cavity or sphenoethmoidal recess sphenoid sinus dysplasia