Wikipedia
A dacryocystocele or timo cyst is a benign, bluish-gray mass in the inferomedial canthus that forms as a result of a narrowing or obstruction of the nasolacrimal duct, usually during prenatal development. The prevalence of dacryocystocele is 1 in 3884 live births.
The diagnosis can be made prenatally; routine obstetric ultrasound can identify the characteristic hypoechoic lesion inferior and medial to the globe. It is important to distinguish a dacrocystocele from the more serious encephalocele, which is a neural tube defect.
If this diagnosis is not made prior to delivery, physical examination usually can provide sufficient evidence of its benign recognition. Timo cysts may spontaneously resolve or with pressure directed toward the nose; however, nasolacrimal duct probing may be required to open the obstruction. While usually filled with sterile mucus, dacryocystoceles occasionally become infected dacryocystitis.