The nasolabial cyst: a nonodontogenic oral cyst related to nasolacrimal duct epithelium.

Nasolabial cysts are interesting, relatively uncommon benign extraosseous maxillary lesions. We review current knowledge about epidemiology, symptoms, imaging modalities, pathogenesis, histopathologic and ultrastructural features, treatment options, and prognosis. Nasolabial cyst lining epithelium is characteristically composed of a basal layer of cuboidal cells and a luminal layer of columnar secretory cells with interspersed mucous goblet cells. In addition, areas of multilayered epithelium and squamous metaplasia may be seen. The cyst stroma is characterized by collagen-rich fibrovascular tissue with variably admixed chronic inflammatory cells. Furthermore, to our knowledge, we report the first example of immunohistochemical protein expression profiling of nasolabial cyst lining epithelium, discovering that basal layer cells express p63 and cytokeratin 5/6, while goblet cells express MUC-2 and MUC-5AC mucins, supporting the notion that nasolabial cysts can be understood as hamartomatous, locally expansile remnants of distal nasolacrimal duct development.