Nasolacrimal duct cyst describes a unilateral or bilateral congenital cyst of the nasolacrimal duct, which is almost always associated with dacryocystocele, presenting most commonly at birth or a few weeks of age (but rarely presenting in adulthood) as a benign, grayish blue mass in the inferomedial canthus or in the nasal cavity, that can cause epiphora, dacryocystitis (inflammation of the lacrimal sac) and nasal obstruction. It is more commonly reported in females.

A disordered proliferation of mature tissues that is native to the site of origin, e.g., exostoses, nevi and soft tissue hamartomas. Although most hamartomas are benign, some histologic subtypes, e.g., neuromuscular hamartoma, may proliferate aggressively such as mesenchymal cystic hamartoma, Sclerosing epithelial hamartoma, Sclerosing metanephric hamartoma.