Case Series of Antrovestibular Polyp: An Unusual Growth of Antral Polyp Toward the Nasal Vestibule Through the Anterior Fontanelle

Background and Objectives: This case series is aimed to introduce a new term, antrovestibular polyp (AVP), for an antral polyp herniating anteriorly toward the nasal vestibule and to describe an antral polyp direction of growth through the anterior and posterior fontanelles.Materials and Method: This is a retrospective study involving review of patients who underwent surgery due to maxillary sinus polyp herniating anteriorly toward the nasal vestibular area or posteriorly toward the choana at a tertiary training hospital from January 2007 through July 2016. Their demographic data, computed tomography scan findings, and endoscopic evaluations were analyzed.Results: This study included 49 subjects; 8 (16.33%, 6 males) with AVP and 41 (83.67%, 24 males) with antrochoanal polyps (ACP). The mean ages of AVP and ACP patients were 9 and 14.4 years, respectively (p=0.006). The subjects were identified as AVP when computed tomography scan showed an antral polyp directed anteriorly toward the nasal vestibular area, while polyps growing toward the choana were identified as ACP. Endoscopic review showed that AVP grew out through an accessory ostium located anterior to the uncinate process at the area of the anterior fontanelle, while ACP started from an accessory ostium of the posterior fontanelle or a widened maxillary natural ostium.