Analysis of type IV frontal cell on an embryological basis

Objective: To analyse the frontal recess in three planes simultaneously and by changing the angle and to discuss the type IV frontal cell on an embryological basis. Methods: A total number of 200 patients (400 sides) who had a cone-beam computed tomography (CT) for various reasons were included in this retrospective study. Patients who had previous nasal or paranasal sinus surgery or were having a history of head or facial trauma, sinonasal tumors, sinonasal polyposis, or fibrous dysplasia, or were with acute or chronic sinusitis were excluded from the study. Type IV frontal cells were analyzed on three planes. Results: Of 200 paranasal CT scans, only three type IV frontal cells were found. On sagittal CTs, two of these cases were the extension of ethmoid cells. In one CT, by changing the angle of the CT, it was found that the lower cell had continuous aeration with agger nasi cell and the upper cell had continuous aeration with the ethmoid cell system. Conclusion: If a type IV frontal cell is seen on a coronal CT scan, the sagittal view should be examined. An isolated cell in the frontal sinus that does not seem to have any contact with the agger nasi is supposed not to be the frontal cell and should be evaluated on the sagittal section to identify the origin of the aeration. If the continuity of the ethmoturbinal system cannot be established, the continuity of the so-called type IV intrafrontal isolated cell can be established with either agger nasi cell or ethmoid cell system by giving different angles to the CT scan