Anatomical Variations Favouring Antrochoanal Polyp Genesis

The antrochoanal polyp (ACP) is a rhinosinusal pseudo-tumour. Its etiopathogenesis is controversial. The antral cyst is thought to be the precursor of ACP. Certain rhinosinusal anatomical variants would favor its transformation into ACP. However, these anatomical variants remain undetermined. The aim of this study was to determine which rhino-sinusal anatomical variants are significantly associated with ACP presence.

This was a retrospective, descriptive and comparative study of 54 patients operated on for ACP. Clinical and paraclinical data were collected from medical records. A sample of 108 nasal cavities was formed based on the patient list. The sample was divided into two groups: the group of nasal cavities with ACP (ACP+) and the contralateral free group (ACP-). The frequency of each anatomical variant was determined in both groups on the basis of imaging. We compared the frequencies in both groups in order to identify anatomical variants significantly correlated with ACP presence.

The majority of patients were aged 15-30 years, with a range of 13-57 years. The gender distribution showed a male predominance, with 33 male patients and 21 female patients (sex ratio = 1.57). Septal deviation was the most frequent anatomical variant (72.2% of all patients). Among the middle turbinate anatomical variants, concha bullosa was the most represented (33.3% of all patients). A statistically significant association was observed between the ACP+ group and the following anatomical variants (p<0,05): concha bullosa, middle turbinate hypertrophy and hyperpneumatized ethmoid bulla. A statistically significant association was observed between the ACP+ group and the nasal cavity side not obstructed by septal deviation (p=0.016). The mean volume of the maxillary sinus was significantly higher in the ACP+ group (p=0,00). A paradoxical middle turbinate was found in one patient on the ACP+ side and in two patients on the ACP- side. One patient had unciform process anatomical variants: verticalization on the ACP+ side, and pneumatization on the ACP- side. The low number of paradoxical middle turbinate and unciform process anatomical variants did not allow a reliable statistical study.

The nasal septum deviation favours contralateral ACP development. However, concha bullosa, middle turbinate hypertrophy and hyperpneumatized ethmoid bulla cells favour ipsilateral ACP development. We recommend systematically reporting anatomical variations on ACP CT scans, performing wide middle meatotomy during ACP removal, correcting variations that may favor recurrence (septal deviation, concha bullosa) during surgery, and closely monitoring patients with such variations for potential recurrence.