Antrochoanal Polyps: Nasal Anatomical and Pathological Variants as Risk Factors.

INTRODUCTION: The etiopathogenesis of antrochoanal polyp remans debatable. OBJECTIVES: To understand antrochoanal polyp development and to assess anatomical and pathological risk factors for its formation. METHODS: This study included 40 subjects with antrochoanal polyp as a study group and a control group of 40 subjects with unilateral maxillary sinusitis. We compared the groups with respect to pathologic variants including the presence of thickened mucosal lining and antral cyst in the contralateral maxillary sinus. We also compared groups regarding anatomic variants such as nasal septal deviation, accessory maxillary sinus ostium, concha bullosa, paradoxical middle turbinate, and uncinate process insertion. RESULTS: Antral cyst was found in the contralateral maxillary sinus was significantly more prevalent in subjects with antrochoanal polyp than in subjects with unilateral maxillary sinusitis. Additionally, nasal septal deviation toward the opposite side of the pathology was significantly more frequent in antrochoanal polyp group than in unilateral maxillary sinusitis group. CONCLUSION: Antrochoanal polyp is suggested to originate from an antral cyst in the maxillary sinus, which extends into the nasal cavity due to pressure changes within the maxillary sinus and nasal cavity. Changes in the nasal cavity airflow caused by nasal septal deviation toward the opposite side of the affected maxillary antrum may represent an important risk factor for antrochoanal polyp formation from a pre-existing antral cyst.