Odontogenic cysts

Introduction Definition Cyst: A pathological cavity filled with fluid, semi-fluid or gaseous contents, which is not created by accumulation of pus. It may or may not be lined by epithelium. Cysts lined by epithelium are known as True Cyst. Ex– Dentigerous cyst, Radicular cyst, Nasolabial cyst etc. Cysts which are not lined by epithelium are known as False cyst or pseudo cyst. Ex- Aneurysmal bone cyst, Traumatic bone cyst, mucous extravasation cyst, Stafne’s bone cyst etc. Depending on the origin of the epithelium lining true cysts we categorize them as Odontogenic or Non odontogenic cyst.

Basic components of cyst Cystic capsule Epithelial lining Lumen

Classification of Odontogenic cysts Based on Etiology – DEVELOPMENTAL Dentigerous cyst Eruption cyst Odontogenic keratocyst* Gingival cyst of newborn Gingival cyst of adult Calcifying odontogenic cyst* Glandular odontogenic cyst INFLAMATORY Periapical cyst Residual cyst Paradental cyst * Reclassified as Odontogenic tumors!!

Classification of Odontogenic cysts Based On Cell Of Origin. DERIVED FROM RESTS OF MALASSEZ Periapical cyst Residual cyst DERIVED FROM REDUCED ENAMEL EPITHELIUM Dentigerous cyst Eruption cyst DERIVED FROM DENTAL LAMINA (RESTS OF SERRES) Odontogenic keratocyst Gingival cyst of newborn Gingival cyst of adult Lateral periodontal cyst Glandular odontogenic cyst UNCLASSIFIED Paradental cyst Calcifying odontogenic cyst.

Dentigerous Cyst (Follicular cyst). Dentigerous cyst can be defined as an odontogenic cyst that surrounds the crown of an impacted tooth; caused by fluid accumulation between the reduced enamel epithelium and the enamel surface. Most common developmental odontogenic cyst. Clinical Features: Always associated with the crown of an impacted,embedded or unerupted tooth. Commonest sites-mandibular & maxillary 3 rd molar & maxillary cuspid areas. Initially asymptomatic later on aggressive lesion causes-expansion of bone,facial asymmetry, displacement of teeth,HOLLOWING OUT ENTIRE RAMUS.

Radiographic features: Cyst reveal a radiolucent area in 3 radiographic variations- Central variety-crown enveloped symmetrically. Lateral variety-enveloped on 1aspect Circumferential variety-entire tooth is enveloped

Hisologic features: Usually composed of thin connective tissue wall with layer of stratified squamous epithelium lining the lumen. Retepeg formation is generally absent. Connective tissue wall is composed of a very loose fibrous connective tissue. Many islands of odontogenic epithelium. RUSTON BODIES present within the epithelium-These are linear,often curved,hyaline bodies of uncertain origin. Content of lumen is thin,watery yellow fluid, occasionally blood tinged. Potential complications – Ameloblastoma; mucoepidermoid carcinoma; squamous cell carcinoma Treatment: Surgical excision or Marsupialization.

ERUPTION CYST It is defined as an odontogenic cyst that surrounds a tooth crown that has erupted through bone but not soft tissue. Whereas the dentigerous cyst develops around the crown of an unerupted tooth lying in the bone, the eruption cyst occurs when a tooth is impeded in its eruption within the soft tissues overlying the bone. Clinically visible as a soft fluctuant mass on the alveolar ridges. This fluctuant cystic cavity if contains blood,appears purple in color it is called ERUPTION HEMATOMA 1

Odontogenic Keratocyst It is derived from the remnants (rests) of the dental lamina, with a biologic behavior similar to a benign neoplasm. Recent classification by WHO had included these lesions in neoplasms. Named so because the epithelium produces so much of keratin that it fills the lumen. The cyst may occur at any age, from the very young to the very elderly. The mandible is affected more frequently than the maxilla. In the mandible, the majority of the cysts occur in the ramus-third molar area. The patient usually is asymptomatic but may have soft tissue swelling, expansion of bone, pain. The cyst may also get secondarily infected.

Roentgenographic features: Radiographically most OKCs are unilocular presenting a well defined peripheral rim. Scalloping of the border is also a frequent finding. Multilocular radiolucent OKCs are also observed, Histologic features: The lining epithelium is highly characteristic, and is composed of: ◦ (1) a parakeratinized surface which is typically corrugated, rippled or wrinkled ◦ (2) a remarkable uniformity of thickness of the epithelium, usually ranging from 6 to 10 cells thick, ◦ (3) a prominent palisaded, polarized basal layer of cells often described as having a “picket fence” or “tombstone” appearance. ◦ No rete ridges are present; therefore, the epithelium often sloughs from the connective tissue ◦ The connective tissue wall often shows small islands of epithelium similar to the lining epithelium - satellite or “daughter” cysts

The variant of OKC that produces only orthokeratin acts somewhat differently than other OKCs. It has a considerably less aggressive behaviour is different entitiy and should bear a different name “orthokeratinized odontogenic cyst” The most important feature of the odontogenic keratocyst is its extraordinary recurrence rate This high recurrance could be because of ◦ Thin and friable lining which makes it difficult to remove intact ◦ It grows by perforating the bone (multilocular) ◦ Presence of satellite cysts in the wall ◦ Prolferative nature of the epithelium

JAW CYST-BASAL CELL NEVUS-BIFID RIB SYNDROME A hereditary condition, it is transmitted as an autosomal dominant trait, it is associated with multiple odontogenic keratocysts. The syndrome is very complex and includes a great variety of possible abnormalities. These may be briefly summarized as follows: (I) cutaneous anomalies, including basal cell carcinoma, other benign dermal cysts and tumors, palmar pitting, palmar and plantar keratosis and dermal calcinosis; (2) dental and osseous anomalies, including odontogenic keratocysts (often multiple), mild mandibular prognathism, rib anomalies (often bifid); (3) ophthalmologic abnormalities, including hypertelorism with wide nasal bridge; (4) neurologic anomalies, including mental retardation, dural calcification, and (5) sexual abnormalities, including hypogonadism in males and ovarian tumors.

DENTAL LAMINA CYST OF NEWBORN This Multiple,solitary,superficial raised nodules on edentulous alveolar ridges of infants are also known as GINGIVAL CYST OF NEWBORN. Resolve without treatment Derive from rests of dental lamina Consists of KERATIN producing epithelial lining. Should not be confused with ‘BOHNS NODULES & EPSTEIN PEARLS Clinical features: Asymptomatic in nature Become sufficiently large to become clinically obvious Appear as small discrete white swellings on alveolar ridge. Do not produce discomfort.

GINGIVAL CYST OF ADULT GINGIVAL CYST OF ADULT Developmental Odontogenic cyst of the gingival soft tissue derived from the rests of dental lamina Occurs in free or attached gingiva Arises from traumatic implantation of surface epithelium May occur at any age Lesion is a small, well circumscribed,painless swelling of gingiva Resembles mucocele Measures over 1 cm in diameter Histologic features: Epithelium is thick ranges from 1 simple flattened layer to several layers. Lining is the stratified squamous Epithelium. Glycogen rich clear cells are present in the lining Lesions are unicystic or polycystic Dental lamina rests may be found in the connective tissue

LATERAL PERIODONTAL CYST LATERAL PERIODONTAL CYST A slow-growing, non-expansile developmental odontogenic cyst derived from one or more rests of the dental lamina, containing an embryonic lining of 1 to 3 cuboidal cells and distinctive focal thickenings (plaques). This is the intrabony counterpart of the gingival cyst of adult. An unusual form of cyst has been seen and known as botryoid odontogenic cyst. This is a multilocular variant which looks like a bunch of grapes. Histologically the cyst is characterized by a thin, nonkeratinized epithelium usually 1 to 5 cell layers thick,. Focal thickened plaques of proliferating lining cells often project into the lumen in areas.

CALCIFYING ODONTOGENIC CYST Also known as GORLIN CYST or CALCIFYING EPITHELIUM ODONTOGENIC CYST This lesion which exists in two forms Type I - Cystic type I A – simple Unicystic type I B – ameloblastomatous proliferating type I C – odontome producing type Type II – Solid The epithelial lining is made up of tall columnar cells and stellate reticulum like cells. Foci of calcifications are seen and GHOST CELLS are present. The solid lesion is now seperated as a tumor and is known as DENTINOGENIC GHOST CELL TUMOR May occur in bone or in gingival soft tissue.

Periapical Cyst Radicular cyst; Apical periodontal cyst; Root end cyst The periapical (radicular) cyst is the most common odontogenic cyst. It is an inflammatory odontogenic cyst The usual etiology is an infected tooth, leading to necrosis of the pulp.. Toxins exit at the apex of the tooth, leading to periapical inflammation. This inflammation stimulates the epithelial rests of Malassez, which are found in the apical periodontal ligament, resulting in the formation of a periapical granuloma that may be infected or sterile. Eventually, this epithelium undergoes necrosis caused by a lack of blood supply, and the granuloma becomes a cyst (periapical cyst).

Radicular cysts can occur in the periapical area of any teeth, at any age but are seldom seen associated with the primary dentition. The majority of cases of apical periodontal cysts are asymptomatic. The tooth is seldom painful or even sensitive to percussion. This type of cyst is rarely is of such a size that it destroys much bone, and even more rarely does it produce expansion of the cortical plates. The radiological image of the radicular cyst is a peri- or para- apical, round or oval radiolucency of variable size which is generally well delineated and most likely with a marked radiopaque rim. Histologic features: the cyst is linied by nonkeratinized stratified epithelium which shows proliferation in an arcading pattern. Rushton bodies are seen The connective tissue shows presence of inflammatory cells. Cholesterol clefts are also seen.