Lateral Periodontal Cyst

Lateral periodontal cyst is a slow growing, developmental odontogenic cyst, that occurs on the lateral root surface of an erupted vital tooth.

There are several theories regarding origin and development of lateral periodontal cyst.

May develop as a dentigerous cyst along the lateral surface of the crown, and as the tooth erupts, it assumes a position in approximation to the lateral root surface.
May originate from the proliferation of Cell rests of Malassez, present in the PDL (stimulus for proliferation not known).
May develop as a primordial cyst of a supernumerary tooth germ (both have high incidence of occurence in the mandibular bicuspid region).
May develop due to proliferation and cystic transformation of rests of dental lamina, present in a post-functional state (limited growth potential, in accordance with the usually small cyst size).

Age : Middle-aged and elderly adults (mean age 50 years).
Location : Mandibular canine and premolar region (75%, characteristic and almost diagnostic) and maxillary lateral incisor area (33%).
Usually asymptomatic. If infected, it may resemble lateral periodontal abscess and even seek to establish drainage.
Commonly associated with vital tooth, unless otherwise affected.

Appears as a radiolucent area along the lateral root surface.
Usually small in size (less than 1 cm).
May or may not be well circumscribed.
Presents with definitive borders, sometimes surrounded by a thin layer of sclerotic bone

Characterised by a thin, nonkeratinised stratified squamous epithelium (usually one to five cell layers thick), with focal epithelial thickenings (often project into the lumen in areas, papillary infoldings are sometimes seen).
The epithelial lining may be composed of cuboidal (or even columnar) cells.
Lining is incomplete and easily sloughs away.
Rests of dental lamina are sometimes found in the connective tissue wall, and are frequently composed of glycogen-rich clear cells.
Connective tissue subjacent to the epithelium exhibits a zone of hyalinisation, consisting of a thick fibrous non-inflamed cyst wall.

Any unilocular radiolucency present on the lateral root surface should be considered in differential diagnosis.

Lateral radicular cyst : Is associated with pulpal infection and a non-vital tooth, lamina dura will not be intact.
Lateral periodontal abscess : Very difficult to distinguish, may exhibit sinus or pus discharge. (Less than 1.5cm is considered as an abscess).
Lateral dentigerous cyst : Generally associated with an impacted tooth i.e, third molars and canines.
Residual cyst : Will present with a history of tooth extraction.
Primordial cyst (arising from a supernumerary tooth and superimposed on adjacent root surface) : Radiographs from a different angulation may help in differential.
Globulomaxillary cyst : Seen as pear shaped radiolucency between maxillary lateral incisor and canine region, at a young age.
Early adenomatoid odontogenic tumors, small ameloblastomas and odontogenic keratocysts.

Surgical enucleation, with attempt to preserve the vital tooth, if possible.
Chances of recurrence are rare when the cyst is unilocular in radiographs.

Gingival cyst is considered the soft tissue analogue of the lateral periodontal cyst : Reports suggest that the lateral periodontal cyst and gingival cyst of adult share the common histogenesis from post-functional dental lamina rests, and these two represent basically the central or intraosseous and peripheral or extraosseous manifestations of the same lesion.
Botryoid odontogenic cyst
- Polycystic variant of the lateral periodontal cyst developing through cystic transformation of multiple islands of dental lamina rests.
- Shows multilocular pattern, radiographically and histologically.
- Have identical epithelial lining, clinical features including age and sites of occurrence.
- Named so because of gross similarity of the cystic cavities to that of a cluster of grapes.
- Have increased risk of recurrence and patients should be followed periodically.

Shafer, Hine, Levy Shafer's Textbook of Oral Pathology (7th edition), Editors - R Rajendran, B Sivapathasundharam, Elsevier.
Textbook of Oral Medicine (3rd edition), Anil Govindrao Ghom, Savita Anil Ghom (Lodam), Jaypee Brothers Medical Publishers (P) Ltd.
Burket's Oral Medicine (13th edition), Michael Glick, Martin S. Greenberg, ,Peter B. Lockhart, Stephen J. Challacombe, Wiley Blackwell.

*This article is an excerpt from the above mentioned books and Medical Sutras does not make any ownership or affiliation claims.