ABSTRACT
<p><b>OBJECTIVE</b>To explore the origin and etiopathogenesis of antrochoanal polyp (ACP) based on the clinical data.</p><p><b>METHODS</b>Twenty-six patients with ACP were included in the study. All the ACP patients were documented by preoperative endoscopy and computer tomographic (CT) scans. All patients were treated under endonasal endoscopic surgery. The relationship between polyp in middle meatus and lesions in the antrum was observed during the surgery. Following surgical removal, the polyps and lesions in the antrum were studied under macroscopy and microscopy.</p><p><b>RESULTS</b>Among 26 cases with ACP, 17 cases were confirmed by preoperative endoscopic examination that polyp originating from antrum ostium, 19 cases showed intimate relationship between the polyp and antrum lesions in CT scan, and 23 cases were found that the polyp originating from the antrum cyst. The pedicle of polyp connected the cyst through autrum ostium, and the polyp existed as a part of capsule wall.</p><p><b>CONCLUSION</b>Based on the data obtained, it is tempting to suggest that the ACP mainly develops from antral cyst, an increase in pressure in cyst forced capsule wall to herniate to middle meatus through the antral ostium, and the continuous herniation and hyperplasy leading to the formation of ACP.</p>