The Spheno-Ostio-Choanal Polyp:  A Rare and Curious Entity

Sphenochoanal polyps originate from within the sphenoid sinus and extend into the choana. There are a few descriptions in the literature of an isolated choanal polyp arising from the external face of the sphenoid. These spheno-ostio-choanal polyps occur in the setting of an otherwise normal sphenoid sinus; they are a curious entity.

Choanal polyps represent only approximately 4% to 6% of all nasal polyps.¹ Most commonly, these large solitary polyps arise from the antrum of the maxillary sinus and are referred to as antrochoanal polyps; however, more rare variants of choanal polyps include those that arise from within the sphenoid and ethmoid sinuses. A sphenochoanal polyp originates from within the sphenoid sinus and extends through the ostium into the choana; polyps arising from the mucosa adjacent to the sphenoid ostium externally also have been described.² These polyps, which occur in the setting of an otherwise normal sphenoid sinus and are more aptly termed spheno-ostio-choanal, are an exceedingly rare and curious entity. We describe the first report, to our knowledge, of isolated, bilateral spheno-ostio-choanal polyps causing nasal obstruction. We obtained approval from the institutional review board of the Saint Louis University School of Medicine.