[Nasopalatine duct cyst].

The nasopalatine cyst is the most common epithelial and non-odontogenic cyst of the maxilla. It is of embryological origin. It is different from a radicular cyst.

[Langerhans cell histiocytosis].

Langerhans cell histiocytosis (ex histiocytosis X) is usually present in children. It is a clonal proliferation of non-functional Langerhans's cells. Histological aspects are variable.