The follicular primordial cyst - odontogenic keratocyst.

Primordial cysts are often associated with unerupted teeth. Superimposition may result in a 'dentigerous cyst' appearance radiographically. There is usually no direct connection between the cyst lining and the follicle of the unerupted tooth. These have been termed envelopmental primordial cysts. In some instances, however, the primordial cyst actually surrounds the crown and the cyst lining is attached to the neck of the tooth in a true dentigerous relationship. We have called these lesions follicular primordial cysts. That portion of the lining immediately adjacent to the neck of the tooth consists of reduced enamel epithelium whereas the rest of the cyst is lined by typical primordial cyst epithelium. We believe that the follicular primordial cyst is extrafollicular in origin and suggest that it arises following eruption of a tooth into the cyst cavity in exactly the same manner as it would erupt into the oral cavity.