Antrochoanal autopolypectomy: CT findings.

Antrochoanal polyp (Killian polyp) is an infrequent, benign lesion of maxillary origin. We describe the basic characteristics of this lesion and a rare case of autopolypectomy. Coronal and axial CT images are presented before and after autoexpulsion of an antrochoanal polyp in a patient with long-standing nasal obstruction. The initial CT examination revealed a typical left antrochoanal polyp filling all the maxillary sinus and passing through the ethmoid infundibulum until the choana. The CT after autopolypectomy showed the secondary mass effect at surrounding structures and residual inflammatory changes.