Choanal polyp originating from the nasal septum: a case report.

Almost all nasal polyps originate from the mucosa of the lateral walls of the nasal cavity or from the paranasal sinuses. A choanal polyp is the intranasal portion of a cyst that has arisen from the wall of the maxillary sinus near the ostium. Medially based polyps, such as those that arise from the nasal septum, are rare. The literature cites a wide range of incidence rates for polyps originating from this structure, but choanal extension of this type of polyp is extremely unusual. This report describes a polyp that arose from the superior aspect of the posterior nasal septum and extended through the choana into the nasopharynx. The histology of this choanal lesion was typical of nasal polyps, but the site of origin is rare. The ethiopathogenesis of nasal polyps with its common location remains controversial so it is difficult to speculate what mechanism triggered the development of this lesion on the nasal septum. Some form of local inflammation may have induced choanal polyp formation at this atypical site.