Unusual large central sphenoethmoidal cell separating the two sphenoid sinuses - A case report

•A central sphenoethmoidal cell that considerably contributes to sphenoid bone pneumatization.•Because both are sphenoethmoidal cells but differ in size and location, this cell is referred to as the “H cell” to distinguish it from the Onodi cell.•The right and left sphenoid sinuses are separated from one another.•H cell is readily mistaken for a sphenoid sinus.