Investigation of the accessory maxillary ostium: a congenital variation or acquired defect?

We sought to determine whether an accessory maxillary ostium (AMO) is a congenital or acquired condition and we investigated concomitant sinus pathologies associated with this structure.

Paranasal sinus CT examinations of individuals aged ≥13 years and <13 years were compared retrospectively. In total, 552 sinuses of 276 patients aged ≥13 years (Group 1) and 284 maxillary sinuses of 142 children aged <13 years (Group 2) were evaluated. Patients were classified as AMO-positive or -negative. The following features were evaluated in Group 1: AMO presence, mucus retention cysts, mucosal thickening, sinusitis of the maxillary sinus, nasal septum deviation, concha hypertrophy, concha bullosa, primary ostium obstruction, uncinate process atelectasis, paradox concha, Agger nasi and Haller cells, and sinus hypoplasia. The sizes and locations of AMOs were also evaluated. The presence of an AMO and sinusitis were evaluated in Group 2.

AMOs were detected in 122 sinuses in Group 1. In the AMO-positive group, sinusitis, mucosal thickening, and primary ostium obstruction were significantly more common than in the AMO-negative group (p < 0.00001). Statistically significant associations were not observed between AMO presence and other parameters. AMOs were present in two sinuses in Group 2.

Our results suggest that AMOs are acquired defects caused by sinus diseases. The rare occurrence of these structures in patients aged <13 years suggests that they may be a perforation or secondary drainage pathway in patients with sinusitis or primary ostium obstruction.