A juxta-ethmoidal course of the infraorbital canal in cases with large ethmomaxillary sinuses or giant Haller cells.

Ethmomaxillary sinuses (EMSs) and infraorbital Haller's cells (HCs) are rare anatomical variations that can impact sinus surgery. Two such rare variants are presented here. Archived computed tomography angiography (CTA) scans were retrospectively analysed. Two cases with an ethmoidal origin of an intramaxillary additional pneumatisation above hypoplastic maxillary sinuses (MSs) were found and examined. In the first case, bilateral EMSs were anterior to the pterygopalatine fossa, transforming the inferior orbital fissure into an ethmomaxillary fissure. Each EMS drained into the superior nasal meatus, which is different from a middle meatal drainage of the MS. The infraorbital sulcus (IOS) was found on the roof of the right EMS but in the angle between the left EMS and MS. In the second case, a complicated air cell anatomy was found: a giant HC reached above the right MS and ethmoidal infundibulum and communicated internally through a narrow isthmus with a retrobullar air cell that, in turn, drained into the upper meatus via an orifice of the basal lamella of the middle turbinate. Posteriorly, the ipsilateral IOS was applied to the posterolateral dehiscent wall of the HC, and the infraorbital canal (IOC) was applied at the HC-MS angle. These cases highlight the anatomical variability of ethmoid air cells' migration within the maxilla and raise awareness of a supra- or juxta-ethmoidal course of the IOS and IOC. This underscores the importance of detailed imaging techniques like CTA for accurate diagnosis and surgical planning. Awareness of such variations is essential to prevent complications during endoscopic sinus surgery.