Choanal and angiomatous polyps of the sinonasal tract.

Choanal and angiomatous polyps can be distinguished from ordinary sinonasal polyps by either a distinctive clinical presentation (choanal) or the histopathologic appearance (angiomatous). Nearly all choanal polyps arise within paranasal sinuses, with the antrochoanal polyp the most common. The angiomatous polyp is most often a secondary change in a choanal polyp and can be mistaken for vascular neoplasms, eg, angiofibroma.