The effect of anatomic variations and maxillary sinus volume in antrochoanal polyp formation

The antrochoanal polyp (ACP), otherwise known as the Killain polyp, is a benign lesion that originates from maxillary sinus mucosa, extending from the accessory ostium towards the middle meatus, and later tends to protrude posteriorly towards the choana and nasopharynx. Many studies have emphasized that its etiopathogenesis is unclear. Research suggests that chronic sinusitis and allergic rhinitis are factors that play an important role in the formation of ACP, as well as anatomical variations. In this study, we aimed to evaluate the effect of anatomical variations and maxillary sinus volume in patients diagnosed with anthrochoanal polyp.

Paranasal sinus computed tomography (PNS CT) images of patients with unilateral ACP patients were examined. The non-ACP sides of the patients comprised the control group. Nasal septal deviation, agger nasi cells, concha bullosa, paradoxical middle turbinate, hyperpneumotized ethmoid bulla, uncinate pathology (medialized or pneumatized uncinate), haller cell, accessory ostium, maxillary sinus retention cyst and maxillary sinus volumes were evaluated.

The study included a total of 54 patients (33 females, 21 males). Mean patient age was 22.92 ± 13.95 (range 6-56) years. Mean maxillary sinus volume was 17.88 ± 5.16 mm³ for the ACP sides and 16.37 ± 4.55 mm³ for the non-ACP sides. Maxillary sinus volume was significantly larger in the ACP side (p = 0.000). Concha bullosa was observed on the ACP side in 23 patients (42.6%) and in the non-ACP side in 21 patients (38.9%). Agger nasi cells were observed in the ACP side in 47 patients (87.0%) and in the non-ACP side in 42 patients (77.7%). Hyperpneumatized ethmoid bulla was observed in the ACP side in 14 patients (25.9%) and in the non-ACP side in 12 patients (22.2%). Haller cells were observed in the ACP side in seven patients (12.96%) and in the non-ACP side in ten patients (18.51%).

Disrupted airflow of the well-developed maxillary sinus cavity due to anatomical variations seems to be an effective factor in the formation of ACP.