Other / Other / MRI

Agger nasi air cells

Agger nasi air cells are normal anterior ethmoidal air cells identified during routine paranasal sinus imaging, typically imaged for chronic rhinosinusitis, drainage pathway obstruction, or preoperative surgical planning.

Key Images

Look For First

Most anterior ethmoidal air cells located anterolateral to the frontal recess
Air cells within the lacrimal bone with close relationship to the orbit and nasolacrimal duct
Cells lying directly anterior to the ethmoidal bullae

Key Image Findings

Agger nasi cells are located anterolateral and inferior to the frontal recess, representing the most anterior ethmoidal air cells
On CT, they appear as small air-filled cavities within the lacrimal bone with well-defined bony margins
Lateral relations include the orbit, lacrimal sac, and nasolacrimal duct, making their location critical for endoscopic surgical planning
The cells lie anterior to the ethmoidal bullae and may narrow or obstruct the nasofrontal recess
Identified in approximately 90% of patients on imaging, making them a very common anatomic variant
They are positioned anterior and above the attachment of the middle turbinate

Differential Diagnosis

Haller cells: located along the medial floor of the orbit rather than within the lacrimal bone; distinguished by more inferolateral position
Supraorbital air cells: located in the orbital roof rather than anterolateral to frontal recess; distinguished by superior location relative to orbital structures
Ethmoidal bullae: located posterior to agger nasi cells; distinguished by more posterior position relative to the nasofrontal recess

Discussion

Agger nasi cells are normal anatomy present in 90% of the population and should not be routinely pathologized unless they contribute to clinical symptoms

When enlarged or due to poor drainage, agger nasi cells can narrow the nasofrontal recess and obstruct frontal sinus drainage, contributing to chronic frontal sinusitis

Understanding the precise location of agger nasi cells within the lacrimal bone is essential during endoscopic sinus surgery to avoid injury to the orbit, lacrimal sac, and nasolacrimal duct

The relationship between agger nasi cells and the nasofrontal recess anatomy is key to understanding frontal sinus drainage pathways and disease mechanisms

Careful anatomic identification helps distinguish agger nasi cells from other ethmoidal air cell variants that may have different clinical significance

Reporting Pearls

Describe the precise location clearly: "Agger nasi air cells present [bilaterally/unilaterally], located anterior to the ethmoidal bullae within the lacrimal bone [normal/enlarged with narrowing of the nasofrontal recess]" to help guide surgical planning and explain potential contributions to frontal sinus disease.

Pitfalls

Mistaking agger nasi cells for pathologic frontal sinus disease when they are simply normal variant anatomy identified in 90% of patients
Confusing agger nasi cells with Haller cells by failing to confirm location within the lacrimal bone rather than along the orbital floor
Overlooking the potential contribution of enlarged agger nasi cells to frontal sinus obstruction when this anatomic variant is present with frontal sinusitis
Failing to recognize the critical anatomic relationships to the orbit and nasolacrimal duct during preoperative assessment for endoscopic sinus surgery

Secondary Links

Home Sinuses Anatomy General Resources