Discussion

Antrochoanal polyps are solitary soft tissue masses, generally originating from the maxillary sinus and extending towards the choana by passing through the sinus ostium. Typically, the polyp passes through the ostium into the middle meatus, without causing bone deformation or destruction. It fills the middle meatus between the middle turbinate and the lateral nasal wall, and grows posteriorly to reach the choana.^{Reference Kizil, Aydil, Ceylan, Uslu, Baştürk and İleri7} Previous studies have shown that antrochoanal polyp is more common in males than in females (with a male-to-female ratio of 1.7:1), and there is a slight predominance for the compromise of the left maxillary sinus.^{Reference Lee, Yoon, Lee and Lim11}

Most of the antrochoanal polyps are broad-based; however, up to 92 per cent of polyps originate from the posterior wall of the maxillary sinus.^{Reference Lee and Huang12} Frosini et al., in their study of 200 cases, suggested that antrochoanal polyp occurred from the combination of an antral cyst and an obstructed maxillary ostium secondary to an anatomical abnormality, such as a deviated nasal septum or a turbinate alteration.^{Reference Frosini, Picarella and De Campora2} Although the exact aetiology of antrochoanal polyp is undefined, allergic rhinitis, chronic sinusitis and lower respiratory tract disorders stand suspicious.^{Reference Maldonado, Martínez, Alobid and Mullol13,Reference Kelles, Toplu, Yildirim and Okur14} In this study, half of the patients were passive smokers or had a history of exposure to animals. One-third of the patients had allergic rhinitis, while one-sixth had asthma.

Clinically, antrochoanal polyp usually presents with unilateral nasal obstruction; however, other symptoms might be present, including epistaxis, purulent rhinorrhoea, post-nasal drip, snoring, dysphonia and dysphagia.^{Reference Maldonado, Martínez, Alobid and Mullol13,Reference Aydin, Keskin, Ustundag, Iseri and Ozkarakas15} Antrochoanal polyp may mimic a wide range of pathologies, although certain clinical and radiological features should raise the index of suspicion.^{Reference Choudhury, Hariri, Saleh and Sandison16}

Nasal endoscopy and CT are excellent tools for diagnosing antrochoanal polyp.^{Reference Yaman, Yilmaz, Karali, Guclu and Ozturk4,Reference Lee, Yoon, Lee and Lim11} On nasal endoscopy, antrochoanal polyp typically appears as a smooth polypoid mass originating in the middle meatus, extending into the choana and nasopharynx, and eventually to the oral cavity.^{Reference Frosini, Picarella and De Campora2} The CT scanning can frequently help, and usually shows: a soft tissue mass filling the maxillary sinus, opacification of the middle meatus, and extension into the choana. A CT scan is, in most cases, sufficient to identify the base of the polyp; however, the presence of another sinonasal abnormality may hinder proper identification of the site. On magnetic resonance imaging, antrochoanal polyp shows hypointensity on a T1-weighted image and hyperintensity on a T2-weighted image.^{Reference Yaman, Yilmaz, Karali, Guclu and Ozturk4,Reference Lee, Yoon, Lee and Lim11}

Antrochoanal polyp differential diagnoses include ipsilateral nasal tumours such as angiofibroma, nasal glioma, encephalocele, mucocele, retention cyst, inverted papilloma or haemangioma.^{Reference Lee, Yoon, Lee and Lim11,Reference Lee and Huang12}

Surgery is the only feasible treatment for antrochoanal polyp. Functional endoscopic sinus surgery is one of the main available procedures. However, sometimes the base of the polyp cannot be completely removed with this technique. This increases recurrence rates,^{Reference Kelles, Toplu, Yildirim and Okur14} as recurrence of antrochoanal polyp is most probably due to regrowth of some missed remaining polypoid lesion within the maxillary sinus.^{Reference Atighechi, Baradaranfar, Karimi and Jafari17} In a recent systematic review, the average recurrence rate for antrochoanal polyp surgery in children was 15 per cent (95 per cent CI = 11.0–21.0).^{Reference Galluzzi, Pignataro, Maddalone and Garavello10} Additionally, Chaiyasate et al. found a higher recurrence rate in children than in adults, with a recurrence time of 1.2 ± 0.6 years.^{Reference Chaiyasate, Roongrotwattanasiri, Patumanond and Fooanant18} The authors also recommended a minimum follow up of two years after surgery in order to detect 95 per cent of recurrences.^{Reference Chaiyasate, Roongrotwattanasiri, Patumanond and Fooanant18} In the present study, the average time between procedures and recurrence was 17.8 ± 14.5 months, with an overall follow-up time of 26.9 ± 11.4 months after the final surgery.

Recurrent antrochoanal polyp is not always innocent, and may cause an evident facial asymmetry due to maxillary expansion. Therefore, the identification of techniques that reduce the recurrence rate is of great importance.^{Reference Nour19} Combined approaches like transcanine sinoscopy, the Caldwell–Luc procedure and the mini Caldwell–Luc procedure are proposed to enable the correct identification and resection of the polyp's antral base.^{Reference Franche, Granzotto and de Borba20}

In the present study, the recurrence rate was 5.8 times lower in those who underwent FESS plus the Caldwell–Luc procedure (p < 0.00001), probably secondary to better exposure and radical excision from the base of the polyp. These findings are similar to those of Kelles et al., who found that patients treated with FESS plus the Caldwell–Luc procedure had a lower rate of recurrence; although, unlike our study, more than 70 per cent of the cases in their series were adult patients.^{Reference Kelles, Toplu, Yildirim and Okur14} They also found higher rates of synechia and bleeding associated with the mucosal injury in the septum and the inferior concha, due to excessive manipulation of the endoscope and surgical instruments.^{Reference Kelles, Toplu, Yildirim and Okur14} Additionally, introducing the endoscopes through the window of a combined approach allows better exposure of the maxillary sinus walls, and the remnant polyp is better resected with the help of forceps or a curette, with less damage to the sinus mucosa. A mini-Caldwell approach also makes it possible to pass an endoscope easily through the anterior wall of the maxillary sinus for better visualisation of its medial wall and floor.^{Reference Atighechi, Baradaranfar, Karimi and Jafari17}

Ozer et al. observed recurrence in patients after FESS and no recurrence after combined surgical procedures.^{Reference Ozer, Ozer and Cagici21} However, Atighechi et al. performed FESS with a mini-Caldwell approach in their patients, and reported minimal recurrences and a low complication rate.^{Reference Atighechi, Baradaranfar, Karimi and Jafari17} A combined approach could ensure the complete removal of the polyp through the two openings according to the position of insertion (posterior, anterior, lateral, medial or inferior wall of the maxillary sinus), and the treatment of the obstructed osteomeatal complex. A wide antrostomy allows good ventilation to the sinus and avoids ostial stenosis.^{Reference Eladl and Elmorsy22} Furthermore, the use of angled endoscopes (45 and 70 degrees) and angled instrumentations can guarantee a complete resection of the polyp by identifying its base in the maxillary sinus.^{Reference Eladl and Elmorsy22}

Disadvantages for the combined approach include the small distance between the developing teeth buds and the infraorbital bundles, which should be accurately studied before opening the anterior wall.^{Reference Eladl and Elmorsy22} Previous studies have demonstrated that maxillary sinus volume in paediatric patients is not affected after the canine fossa puncture approach in paediatric patients with antrochoanal polyp.^{Reference Lee, Baek, Kim, Byun, Lee and Hong23} Orvidas et al. found facial paraesthesias in 10 per cent of their patients treated with the Caldwell–Luc approach.^{Reference Orvidas, Beatty and Weaver6} In the present study, no complications were reported during surgery or follow up in any of the patients undergoing a combined approach.