[Congenital lacrimonasal duct cyst: Do not forget this radiological and clinical entity].

Although obstruction of the lacrimonasal duct is a fairly common finding in newborns, development of a dacryocystocele (nasolacrimal duct cyst) is uncommon and is caused by stenosis in the proximal and distal area of the nasolacrimal duct leading to a cystic dilatation. Its diagnosis remains difficult for the pediatrician, the ENT specialist, the ophthalmologist, and the radiologist. The study of six cases of dacryocystocele and the review of the literature led the authors to describe the clinical and radiological features of this uncommon entity. The symptomatology includes nasal obstruction and, when bilateral, significant respiratory distress in the newborn (obligate nose-breather) and dilatation of the lacrimal duct with blue cystic swelling inferior to the medial canthus or with an inflammatory aspect of the lacrimal duct in case of infection. A careful endoscopic examination of the nasal cavities and CT or MRI imaging reveals a cystic tumor, which arises in the inferior meatus, inferolateral to the inferior turbinate, and can partly or completely obstruct the endonasal space, uni- or bilaterally. CT and MRI are equally sensitive in detecting dacryocystocele and are also useful for differential diagnosis for other cystic or tumoral nasal lesions such as meningoencephalocele, dermoid cyst, and glioma. To avoid the risk of potential complications (respiratory distress or even sudden infant death, infectious ophthalmologic complications), this radiological and clinical entity should not be forgotten. Endoscopic marsupialization leads to immediate and definitive healing recovery.