Odontogenic Cysts

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Odontogenic Cysts by Mind Map: Odontogenic Cysts

1. Inflammatory Periodontal Cyst (Apical/ Periapical/ Radicular)

1.1. 1. Etiology

1.1.1. 1. represent 65% of cyst

1.1.2. 2. due to inflammatory hyperplasia of epithelial rests of Malassez in PDL after death of pulp

1.1.3. 3. either apical (near root apex) or lateral (near accessory root canal exit), or residual (left after extraction)

1.1.4. 4. develops from periapical granuloma due to inflammatory process within

1.1.5. 5. as proliferation continue epithelial mass increase in size by division of cells on periphery

1.1.6. 6. in the central area of mass degeneration and liquefaction occurs as it is far away from nutrition sources

1.1.7. 7. result is epithelial lined cavity filled with fluid forming apical periodontal cyst

1.1.8. 8. another suggestion is that cyst may form through proliferation of epithelium to line pre existing cavity formed by focal necrosis, and degenration of c.t in periapical granuloma

1.2. 2. Mechanism of Enlargement

1.2.1. 1. Remnants of cellular debris found within cyst lumen increase osmotic pressure of cystic fluid due to breakdown of complex tissue protein into larger number of simple proteins

1.2.2. 2. this causes fluid transport across epithelial lining and C.T that act as a semipermable membrane

1.2.3. 3. fluid ingress in lumen results in outward ingrowth of cyst

1.2.4. 4. this growth stimulates osteoclastic activity and resorption of surrounding bone allowing more expansion

1.2.5. 5. bone resorption also stimulated by bone resorbing factors from inflammatory cells and cellular elements within peripheral portion of lesion

1.3. 3. Clinical Features

1.3.1. 1. age 1. third to sixth decades

1.3.2. 2. sex 1. more frequent in men

1.3.3. 3. site 1. maxilla specially anterior region

1.3.4. 4. Symptoms 1. most are asymptomatic and discovered during routine radiographic examination 2. as they enlarge they cause painless swellings often on buccal side 3. if infection occurs swelling becomes painful and may rapidly increase in size due to edema 4. swelling is rounded and hard at first 5. later when reduced to eggshell thickness crackling sensation may be felt under pressure 6. part of overlying bone is absorbed entirely leaving a soft fluctuant swelling bluish beneath mucosa 7. usually there is a non vital tooth from which cyst has developed

1.4. 4. Radiographically

1.4.1. 1. round or oval well defined radiolucency

1.4.2. 2. narrow opaque margin -may not be apparent if actively enlarging-

1.4.3. 3. range from 5mm to several cm in diameter

1.4.4. 4. dead tooth has large carious cavity or filling

1.4.5. 5. root resorption of tooth is noted

1.4.6. 6. very large cyst in maxilla may extend in any direction and become irregular

1.4.7. 7. infection causes outline to become hazy

1.4.8. 8. distinction between small radicular cyst and periapical granuloma is difficult

1.5. 5. Histopathological Features

1.5.1. 1. Epithelial lining of cyst is usually stratified squamous epithelium wirh acanthosis (20 layer

1.5.2. 2. newly formed cyst epithelium is hyperplastic exhibiting rings over vascularized C.T and inflammatory cells

1.5.3. 3. In fully formed cyst epithelial lining is regular and flattened inflammation subsides and C.t has few inflammatory cells

1.5.4. 4. epithelium lining the cyst may be discontinous and frequently missing

1.5.5. 5. underlying ct composed of bundles of collagen with variable numbers of fibroblasts and capillaries. inf cell infiltration also present

1.5.6. 6. toward epithelium PMNLs predominate

1.5.7. 7. Deeper in C.T lymphocytes are more common

1.5.8. 8. in C.T wall of the cyst foci of dystrophic calcification, cholestrol clefts and enlarged blood vessels may be found

1.5.9. 9. Degenerated plasma cells may be present known as russel bodies 10. Multinucleated foreign body giant cells may be close to cholestrol clefts and haemosiderin within C.T wall

1.5.10. 11. occasionally mass of cholestrol erodes through lining of epithelium and is extruded into cyst lumen

1.5.11. 12. source of cholestrol seems to be due to local tissue damage

1.5.12. 13. collection of lipid filed macrophages (foam cells) or macrophages containing hemosiderin are present

1.5.13. 14. lumen of cyst contain fluid which stain eosinophilic soemtimes lumen may contain cholestrol in great amounts

1.5.14. 15. chemically cystic fluid contain serum albumin, globulin, cholestrol and nucleoproteins

1.6. 6. Differential Diagnosis

1.6.1. 1. Periapical granuloma if radiolucency is small

1.6.2. 2. Periapical scar or surgical defect if previously treated

1.6.3. 3. Early phase of periapical cemental dysplasia in anterior mandibular area, but related teeth are usually vital

1.7. 7. Microscopic Variation in Cyst walls

1.7.1. 1. pseudo-stratified ciliated columnar epithelium, seen near maxillary teeth involving sinus

1.7.2. 2. dystrophic calcification

1.7.3. 3. keratinized para or ortho

1.7.4. 4. hyaline bodies or rushton bodies in epithelial lining 1. thin, linear,cuved bodies, amorphous in structure, eosinopilic in reaction. 2. origin is controversial may be due to hematogenous origin from thromus formation in small cappilaries, being chiefly formed of RBCs as in rouleu phenomenon 3. may be odontogenic in origin

1.8. 8. Treatment

1.8.1. 1. if the cyst is small, enucleation of cyst and apisectomy of involved tooth

1.8.2. 2. if medium size remove tooth and enucleate cyst

1.8.3. 3. large cyst need marsupialization to avoid antrum or imporrtant structure as inferior dental canal

1.8.4. 4. larger cyst need enucleation and bone chips to fill the cavity

1.9. 9. Other Similar types

1.9.1. 1. 1- Lateral PDL cyst 1. less common 2. form at side of root of pulpless tooth as result of opening of lateral root canal and irritation of pdl

1.9.2. 2. 2- Residual cyst 1. pulpless tooth from which periapical cyst has arisen may be extracted and cyst may persist in jaw 2. one of most common causes of swelling of edentulous jaw

2. Developmental PDL Cyst

2.1. 1. Definition

2.1.1. 1. non inflammatory developmental cyst occurring adjacent or lateral to root of vital tooth

2.2. 2. Etiology

2.2.1. 1. due to proliferation of odontogenic epithelium at lateral sides of root of adjacent vital tooth

2.3. 3. Clinical Features

2.3.1. 1. age 1. 40-60

2.3.2. 2. sex 1. male 2x female

2.3.3. 3. site 1. upper lateral incisor 2. lower premolar and canine region

2.3.4. 4. Appearance 1. no signs or symptoms and may be discovered during routine radiographic examination of related tooth 2. may cause slight bulge over mucosa when located labially on root 3. related tooth is vital 4. when infected it resembles lateral pdl cyst

2.4. 4. Histopathologically

2.4.1. 1. cystic cavity lined by stratified squamous epithelium which is thin composed of 1 or 2 layers

2.4.2. 2. epithelial cells shows clear cytoplasm and deeply staining nuclei

2.4.3. 3. parakeratin or orthokeratin formation by epithelial lining

2.4.4. 4. inflammatory cells may be present in C.T wall but it is a 2ry reaction when cyst is infected

2.5. 5. Radiographically

2.5.1. 1. radiolucent area

2.5.2. 2. small rarely over 1 cm in diamter

2.5.3. 3. may or may not be well defined with radioopaque margin

3. Developmental Gingival Cyst of Adulthood

3.1. 1. defined

3.1.1. 1. non inflammatory developmental cyst occuring adjacent to vital tooth in gingiva

3.2. 2. Etiology

3.2.1. 1. from remnants of dental lamina in soft tissue between oral epithelium and periosteum

3.3. 3. Clinically

3.3.1. 1. age 1. any age most commont 40-60 years

3.3.2. 2. sex 1. same in male and female

3.3.3. 3. appearance 1. small well circumscribed painless swelling of gingiva less than 1 cm in diameter 2. may involve free or attached gingiva and sometimes gingival papilla itself 3. lesion has same color as normal mucosa sometimes lesion erode and underlying bone assume slight bluish discoloration

3.4. 4. radiographic appearance

3.4.1. 1. -ve on xray

3.5. 5. histopathological features

3.5.1. 1. epithelium lined cavity

3.5.2. 2. epithelium is thin and flattened st. sq epithelium

3.5.3. 3. most cases non keratinized occasionlally some keratin formaion may be seen

4. Gingival Cyst of New Born (Bohn's Nodules)

4.1. 1. Info

4.1.1. 1. multiple white nodules not more than few mm in diameter on alveolar ridge

4.1.2. 2. originating from dental lamina which proliferate to cyst

4.2. 2. clinically

4.2.1. 1. asymptomatic

4.2.2. 2. most cases cyst degenerate rupture and resolve spontaneously

4.3. 3. Histopathology

4.3.1. 1. thin epithelial lining 2 or 3 layer thick and lumen is filled with desquamated keratin

4.3.2. 2. similar epithelial inclusion cyst may occur along midline of palate Median Palatine cyst of new born (Epstein Pearls)

4.3.3. 3. developmental in origin but not derived from odontogenic epithelium

4.3.4. 4. epithelium originates as inclusions at them fusion between 2 palatal shelves and nasal septum

4.4. 4. treatment

4.4.1. 1. no treatment : cysts usually fuse with overlying oral mucosa and discharge contents during neonatal period

5. Dentigerous Cyst (Follicular)

5.1. 1. Info

5.1.1. 1. means containing tooth

5.1.2. 2. surrounds crown of unerupted tooth

5.1.3. 3. represent 15-17% of all cysts of jaws

5.2. 2. Etiology

5.2.1. 1. originates through cystic changes in reduced enamel epithelium

5.2.2. 2. after complete formation of enamel of tooth with accumulation of fluid between reduced enamel epithelium and crown

5.2.3. 3. attached cyst lining at CEJ suggest origin

5.2.4. 4. cyst forms between layers of REE

5.2.5. 5. layer that remains attached to surface of enamel is of negligible thickness and may degenerate

5.2.6. 6. cause is not known, there is an association between failure of eruption of teeth and formation of dentigerous cyst or cyst prevent eruption

5.2.7. 7. expansion of dentigerous cyst is related to 2ry increase in cystic fluid osomolarity due to desquamated epithelial cells into cyst lumen

5.2.8. 8. mitotic index is low in comparison with primordial

5.3. 3. Clinically

5.3.1. 1. age 1. incidence common in 2nd and 3rd decades

5.3.2. 2. sex 1. more in males

5.3.3. 3. site 1. more in mandibular 3rd molar and maxillary canine areas it may involve supernumerary tooth or odontome 2. uncomplicated dentigerous cyst cause no symptoms and may be discovered accidentally 3. as cyst grow within bone it cause resorption and expansion with face asymmetry 4. displacement of teeth and resorption of root of adjacent teeth 5. usually there is pain and increased swelling when infected

5.4. 4. Radiographically

5.4.1. 1. well defined radiolucency associated with crown of unerupted tooth sometimes it is surrounded by thin sclerotic line

5.4.2. 2. most commonly it is central or pericoronal enveloping crown and producing pressure on its occlusal surface opposite to movement of eruption

5.4.3. 3. may develop one one side of crown (lateral dentigeorus cyst ) with lower 3rd molar

5.4.4. 4. maxillary dentigerous cyst in canine region may expand distally or superiorly

5.4.5. 5. long standing extending toward roots of adjacent teeth, root resorption noted in 50% of cases

5.5. 5. Histopathological Features

5.5.1. 1. cyst is lined by thin regular non keratinized stratified squamous epithelium attached to tooth at CEJ

5.5.2. 2. in inflamed cyst lining is about 2-4 cell thick

5.5.3. 3. c.t epithelium is flat

5.5.4. 4. when 2ry infection occur rete pegs develop

5.5.5. 5. variations: ciliated columnar, hyaline bodies, keratinized epithelium

5.5.6. 6. C.T rich in glyoproteins and mucopolysaccharides

5.5.7. 7. inflammatory cells are abscent

5.5.8. 8. cholestrol clefts may be found

5.5.9. 9. foreign giant cells may be seen

5.5.10. 10. epithelial discontiniuation may be seen

5.5.11. 11. macroscopically may reveal small thickenning proliferation strnds of odontogenic epithelium that may exhibit follicular arrangement and may change to ameloblastoma

5.5.12. 12. cyst content 1. yellowish fluid of cholestrol crystals if acutely infected may become purulent

5.6. 6. Diff Diagnoisi

5.6.1. 1. unilocular ameloblastoma

5.6.2. 2. OKC

5.6.3. 3. Adenomatoid odontogenic tumor

5.6.4. 4. ameloblastic fibroma

5.7. 7. treatment

5.7.1. 1. removal of associated tooth and enucleation of cyst

5.7.2. 2. large cyst of mandible may need marsupialization to allow for decompression and shrinkage of bony defect

5.8. 8. complications

5.8.1. 1. transform to ameloblastoma

5.8.2. 2. carcinoma transformation

5.8.3. 3. destruction of large area of jaw with possible fracture

6. Eruption Cyst

6.1. 1. Info

6.1.1. 1. uncommon superficial dentigerous cyst occur on soft tissue of gum or alveolar mucosa over tooth about to erupt

6.1.2. 2. it's dilatation of normal follicular space above crown of erupting tooth caused by accumulation of tissue fluid or blood

6.2. 2. clinical

6.2.1. 1. age 1. children decideous or permenant

6.2.2. 2. site 1. gum over erupting tooth

6.2.3. 3. shape 1. soft rounded swelling if blood is present it appears deep blue name eruption haematoma

6.3. 3. treatment

6.3.1. 1. not needed as during eruption cyst resolve spontaneously, if tooth can't erupt tissue overlying crown may be removed to allow eruption

7. Primordial Odontogenic Keratocyst

7.1. 1. defintion

7.1.1. 1. cyst occur in place of tooth owing to cystic degenration of its enamel organ

7.1.2. 2. some other cyst produces keratin

7.1.3. 3. however OKC have specific histology and behaviour

7.2. 2. Etiology

7.2.1. 1. it arises from enamel organ before tooth formation

7.2.2. 2. cyst which arise with no missing tooth arise from supernumerary teeth germ

7.2.3. 3. stimulus which initiates proliferation of cell rests to form cyst is unknown may be genetic

7.3. 3. Clinical Features

7.3.1. 1. least common 7%

7.3.2. 2. age 1. second and 3rd decades

7.3.3. 3. sex 1. no sex predilection

7.3.4. 4. site 1. in posterior portion of mandible. maxillary lesion in 3rd molar and then canine

7.3.5. 5. appearance 1. at site where tooth is abscent may cause expansion 2. usually asymptomatic if infected cause parathesia to lower lip pain and swelling of jaw , displacement of teeth

7.4. 4. radio

7.4.1. 1. uniocular or multilocular 1. unilocular well defined with smooth margin and thin RO line may be below roots of teeth, between roots, or near crest of ridge 2. multilocular can be distinguished from ameloblastoma

7.5. 5. cyst content

7.5.1. 1. keratin seen as dirty white or yellowish material similar to pus without bad smell

7.5.2. 2. fluid also contain plasma protein

7.6. 6. histopathology

7.6.1. 1. lining thin regular continous layer of st. sq. epithelium 6-8 cell thick arising from smooth basement membrane

7.6.2. 2. basal cells are columnar palisaded with prominent polarized intensly stained nucei

7.6.3. 3. cells of st. spinosum show inter cellular edema

7.6.4. 4. surface is corrugated with parakeratotic surface layer can be seen shedding individual or cluster of sq. into cyst lumen

7.6.5. 5. lumen may contain large number of keratin debris or clear fluid

7.6.6. 6. mitotic index is more than radicular cyst similar to ameloblastoma

7.6.7. 7. parakeratocystic type form 85-95%, 5% ortho (less agressive and low recurrence

7.6.8. 8. variations of parakertinized keratocyst 1. budding of basal layer into underlying C.T 2. daughter cells may form within C.T wall of cyst (small or large islands of epithelial cells exhibiting central keratinization and microcyst formation 3. recurrence rate is high: 40% 1. reasons

8. Keratinizing and Calcifying Odontogenic Cyst

8.1. 1. definition

8.1.1. 1. developmental odontogenic lesion has some features of cyst but many character of neoplasm

8.2. 2. Etiology

8.2.1. 1. believed to be derived from odontogenic epithelial remnants within gingiva or within mandible or maxilla

8.3. 3. Clinically

8.3.1. 1. age 1. before 40 years 2. sex 1. more common in females 3. site 1. more in maxilla and anterior of mandible 2. 75% intraosseous 25% present in gingiva of retromolar area 4. appearance 1. painless swelling in gingiva or alveolar bone 2. as cyst enlarge it displaces root of adjacent teeth 3. if it is infected it becomes painful

8.4. 4. radiographically

8.4.1. 1. Intraosseous KCOC is unilocular or multilocular

8.4.2. 2. have well defined irregular margins

8.4.3. 3. within radiolucency there is scattered calcification with variable density

8.4.4. 4. some times radiolucency is diffused giving salt and pepper appearance

8.4.5. 5. sometimes mineralization is very extensive that radiographic margin of lesion is hard to determine

8.4.6. 6. 1-8 cm in diameter

8.5. 5. Histopathological features

8.5.1. 1. lumen lined by st. sq. epithelium

8.5.2. 2. have columnar or cuboidal layer of cells with darly stained nuclei polarized away from basement membrane

8.5.3. 3. in solid lesion intraluminal epithelial proliferation will fill cyst lumen

8.5.4. 4. epithelial layer is irregular and of variable thickness

8.5.5. 5. lining is similar to ameloblastic type of epithelium

8.5.6. 6. above basal layer more loosely arranged epithelial cells that resemble stellate reticulum of enamel organ

8.5.7. 7. epithelium may proliferate the cells become swollen with hyaline homogenous cytoplasm that stains deeply eosinophilic

8.5.8. 8. nuclei undergo karyolysis as keratinization progress so ghost cells are seen

8.5.9. 9. ghost cells may undergo dystrophic calcification and become basophilic

8.5.10. 10. in other areas of cyst lining and in fibrous c.t wall there are irregular eosinophilic masses considered as dentinoid

8.5.11. 11. if full thickness of epithelium is affected by ghost cells may be shed into cavity of cyst

8.5.12. 12. ghost cells may be broken coming in contact with c.t wall

8.6. 6. Differntial diagnosis

8.6.1. 1. early lesion is differntiated from ameloblastoma when mixed rl-ro appearance is present and must be differntiated from adenomatoid odontogenic tumor

8.7. 7. treatment

8.7.1. 1. simple enucleation