Nasolacrimal Duct Dacrocystocele

A nasolacrimal duct dacrocystocele (also known as a dacryocele, amniotocele, and nasolacrimal mucocele) is an uncommon medial canthal mass in children. There may rarely be a connection to a cyst in the nasal cavity. It is called dacryocystitis when infected.

CT shows a low-attenuation thin-walled cyst along the medial canthus associated with smooth enlargement of the nasolacrimal duct. The cyst is so large that it superiorly displaces inferior turbinate (arrow). In some cases, it can extend further and deviate the nasal septum. Contrast enhanced images (not shown) will demonstrate minimal if any thin peripheral enhancement. It is of variable signal intensity on T1-weighted images depending on protein content and is usually T2-hyperintense.

Fat stranding and other usual inflammatory changes can be seen with infection.

Differential considerations include:

• Dermoid/Epidermoid: Usually affects the lateral canthus. Will have fat content with thin rim-enhancement, with or without calcification.
• Acquired dacrocystocele: Usually in adults. This is caused by a stenosis of the nasolacrimal duct from inflammation, cancer, trauma (e.g., LeFort 2 fracture, sinus surgery).
• Nasoorbital cephalocele: Only a consideration if you have a single slice. Scrolling up will reveal that the cyst is contiguous with intracranial contents through a bony defect.

References

• Castillo M, Merten DF, Weissler MC. Bilateral nasolacrimal duct mucocele, a rare cause of respiratory distress: CT findings in two newborns. AJNR Am J Neuroradiol. 1993 Jul-Aug;14(4):1011-3.
• Meyer JR, Quint DJ, Holmes JM, Wiatrak BJ. Infected congenital mucocele of the nasolacrimal duct. AJNR Am J Neuroradiol. 1993 Jul-Aug;14(4):1008-10.
• Rand PK, Ball WS Jr, Kulwin DR. Congenital nasolacrimal mucoceles: CT evaluation. Radiology. 1989 Dec;173(3):691-4.