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Oral Pathology Exam 3 > 4. Odontogenic Cysts > Flashcards

4. Odontogenic Cysts Flashcards

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1
Q

What is an Odontogenic Cyst?

A
  • Pathologic cavity lined by epithelium derived from tooth-formative cells
    • Must be a cavity, and lined by epithelium to be a true cyst
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2
Q

What are the 4 possible sources of odontogenic epithelium?

A
  1. Dental lamina gets left in the jaws and gingiva
  2. Rests of Malassez
    • ​​Broken off pieces of Hertwig’s sheath that reside in PDL
  3. REE that lines the follicle
  4. Rests of Serres
    • ​​Small buds of resting odontogenic epithelium (dental lamina) that live in the gingiva
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3
Q

What is the most common odontogenic cyst?

A

Periapical Cyst

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4
Q

How do PA cysts develop and grow? (3)

A
  • Within pre-existing PA Granuloma from inflammatory stimulation of rests of Malassez
  • As the rests proliferate, the central epithelium degenerates (becomes necrotic) to form the cyst lining
  • Continues to grow from hemodynamic pressure = Oncotic Edema
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5
Q

Location of Periapical Cyst

A

ONLY around the apex of a non-vital root

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6
Q

What age group is affected by Periapical Cysts?

A

Adults

  • Rare in children, because a rxn to a non-vital deciduous tooth occurs in the furcation, not the apex.
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7
Q

What is the radiographic appearance of Periapical Cysts? (4)

A
  • Well-demarcated, spherical RL
  • Epicentered over apex of non-vital root
  • Absent lamina dura around apex
  • No PDL space
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8
Q

Which are more likely to be larger, cysts or granulomas?

A

Cysts

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9
Q

What is the clinical presentation of Periapical Cysts? (4)

A
  • Typically no signs or symptoms
  • May show mild discomfort to percussion or tooth “feeling different” from adjacent teeth, not pain.
  • Painful ONLY if secondarily infected, typical pa cysts are not infections
  • Some are large, expansile, and produce flutuant swelling, and can erode bone
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10
Q

What is the Histology of a Periapical Cyst? (2)

A
  • Stratified squamous, non-keratinizing epithelium overlying an inflammed collagenous cyst wall
  • Inflammatory Changes due to:
    • Epithelial Rxn
      • ​Thinned out and hyperplastic epithelium
    • Cholesterol​
      • _​_Deposited as slits in CT, “white crystal” appearance
      • Gets gobbled up by macs, forming foam cells
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11
Q

What is the treatment for a Periapical Cyst? (3)

A
  • Root Canal Therapy with follow-up to ensure resolution
  • Apical Surgery with Biopsy if …
    • RL remains > 6 months OR grows
    • Failed RCT
    • Misdiagnosis
  • If the pt denies RCT, extraction of tooth
    • Biopsy of curetted periapical soft tissue
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12
Q

What is the rationale for treating Periapical Cysts?

A
  • Known to become malignant SCCA
  • Other pathology can mimic pa cysts, rct done on vital teeth all the time
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13
Q

What is the 4th most common odontogenic cyst?

A

Residual Cyst

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14
Q

What is the pathogenesis of a Residual Cyst? (3)

A
  • Formed from rest of Malassez
  • A cyst that remains after the associated tooth is removed
    • ​Most are Periapical Cysts that were left after the tooth was extracted
  • No relationship to teeth
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15
Q

What is the most likely odontogenic cyst to transform into SCCA?

A

Residual Cyst

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16
Q

What is the 4th most common odontogenic cyst?

A

Residual Cyst

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17
Q

What is the only way to diagnose a Residual Cyst?

A

Histology + No assoc tooth

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18
Q

What is the 2nd most common odontogenic cyst?

A

Dentingerous Cyst

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19
Q

What is a Dentingerous Cyst?

A

Developmental cyst of the follicle of an unerupted or impacted tooth

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20
Q

What is the cyst lining of a Dentingerous Cyst derived from?

A

REE lining the follicle

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21
Q

What is the cyst wall of a Dentingerous Cyst derived from?

A

CT of the follicular sac

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22
Q

What age is affected by Dentingerous Cysts?

A
  • Any age, but peaks in 3rd decade
  • Rare in children
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23
Q

Where are Dentingerous Cysts found, what is the most common of the locations?

A

Areas most likely to have impacted teeth

  1. Mandibular 3rd Molar
  2. Canines
  3. Maxillary 3rd Molars
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24
Q

What is the radiographic appearance of Dentingerous Cysts? (4)

A
  • Circular, uni-locular, peri-coronal RL, around an impacted OR unerupted tooth
  • NEVER multilocular
  • Attaches at cervical area of crown at acute angle
  • Can get huge and fill up entire ramus
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25
What is the clinical presentation of a dentingerous cyst? (3)
* Most cases **asymptomatic** * Large examples can cause **swelling** * Can become **secondarily infected** and **inflamed**
26
What is the Histology of Dentingerous Cyst? (3,1)
* Identical to PA Cyst * May show **secondarily inflammation** if it breaks through the bone (food and other stuff can enter the cyst) * **REE** is **pluripotent** and can transform into more significant pathology * REE commonly produces **mucous cells** in Dentingerous Cysts
27
What complications are associated with Dentingerous Cysts? (4)
* _Malignant Transformation_ due to REE pluripotent potential * **Ameloblastoma** can arise in pre-existing dentingerous cysts * **MEC** that started out centrally (jaws) in a DC * _Infection_ * DC's that become infected can transform into **SCCA** * **Resorption of roots** or **PD of 2nd molar** * Pathologic **fracture** at the **angle of the jaw**, if big enough
28
What is the treatment and prognosis for a Dentingerous Cyst?
* **Enucleation** (shell it out) and **biopsy** to rule out pathology * **No recurrences** if completely removed
29
What population are Eruption Cysts found in?
Kids
30
What is the pathogenesis of Eruption Cysts?
**Dentingerous Cyst** that forms in **soft tissue** during **tooth eruption** * Area of RL seen as DC is formed * As eruption occurs the tooth pushes the cyst to the surface
31
Where are Eruption Cysts found? (2)
* 1st molars * Maxillary Central Incisors
32
What is the clinical appearance of an Eruption Cyst?
**Fluctuant**, **soft blue dome**, before the tooth erupts
33
What is a Hyperplastic Dental Follicle?
Not a Cyst Represents a **thickening** of the **fibrous wall** of the **dental follicle**
34
What is the size of a Hyperplastic Dental Follicle?
Small, **2-4mm** from the tooth to the lesion border ## Footnote *If _\>_ 5mm = Dentingerous Cyst*
35
What is the histology of a Hyperplastic Dental Follicle? (3)
* **Normal follicular REE lining**, and fibrous wall thickened with _myxoid ground substance_ * **No squamous epithelium** * *Can look like an **Odontogenic Myxoma***
36
What is the least common odontogenic cyst?
Lateral Periodontal Cyst (2%)
37
Where are Lateral Periodontal Cysts found?
* Always appears in **interradicular bone, in-between 2 teeth** * _Only 2 Locations_ * **Mandibular Premolar Area** (75%) * Has to have a pm on at least 1 side * **Maxillary Incisor Area** (20%)
38
What population are Lateral Periodontal Cysts most common in?
**Males** **\> 40 yrs**
39
What are Lateral Periodontal Cysts derived from?
**Post-functional dental lamina** sitting in _bone_
40
What is the diagnostic radiographic appearance of Lateral Periodontal Cysts? (4)
* **Small (4-10mm)** innocuous cyst * **Circular RL**, with **corticated upper border** within interradicular bone * Associated with **vital teeth** * ​Lamina dura and PDL space are intact * No swelling or symptoms
41
What is the super diagnostic histology of lateral periodontal cysts? (3)
* Cyst wall = thin, densely collagenous **non-inflammatory** * **Cuboidal** odontogenic epithelial lining, * With **focal (mural) thickenings** of plaques of **swirled/clear cells** that project into lumen
42
What is the treatment for Lateral Periodontal Cysts? (3)
* **Completely Innocuous** * Will not grow, cause any symptoms, or turn into cancer * **Enucleate** without harming adjacent teeth * **Must biopsy**, counterintuitive * ***25%** that radiographically look like LPC are actually **OKC’s** under the microscope*
43
What is the only cyst exclusively in soft tissue (not in bone)?
Gingival Cyst
44
What is the gingival cyst derived from?
**rests of Serres** that live in **gingiva** ## Footnote *Same cells that cause LPC, but these aren't in bone*
45
Where are Gingival Cysts found?
* ONLY on the **buccal** aspect of **mandibular premolar area** * Occasionally in **upper incisor area** * *Soft tissue equivalent of the LPC, same location*
46
What population is affected by gingival cysts?
ONLY in **Adults**
47
What is the 3rd most common cyst?
ODontogenic Keratocyst (OKC)
48
What is the clinical presentation of an Odontogenic Keratocyst?
* An **aggressive**, **cystic neoplasm** that continues to **expand** **within medullary bone**, producing a **large destructive lesion** * ​Expansion due to _active growth_*, rather than inflammation/hemodynamic causes*
49
What are OKCs derived from?
**rests of dental lamina** *Not post-functional dental lamina like in LPC, this still has growth potential*
50
What population do OKCs occur in?
**Any age**, prefers **Adults**
51
What location do OKC's occur in?
* Any location of **tooth formative epithelium** * Prefers **mandibular 3rd molar** region (50%) * Never begins in the ramus, below the level of the mand canal * It may expand there eventually
52
In the mandibular 3rd molar region what do OKC's mimic?
Dentingerous Cysts
53
What percent of Dentingerous Cysts were dx incorrectly and are actually OKC's?
9%
54
What percent of Periapical Cysts were dx incorrectly and are actually OKC's?
\<1% This is actually alot because PA Cysts are so frequent
55
What percent of Residual Cysts were dx incorrectly and are actually OKC's?
12%
56
What percent of Lateral Periodontal Cysts were dx incorrectly and are actually OKC's?
25% * *This is why we do biopsies on them, even though they are innocuous.* * *A radiograph isn’t sufficient, but their histology is diagnostic.*
57
What occurs when OKCs are left alone?
* They become **multilocular RL** * They can mimic **Ameloblastomas** or **Myxomas** * OKCs are more common than both of these combined
58
What are the Characteristic Histologic Findings of a non-inflamed OKC? (5)
* **Thin epithelium w/o rete ridges** * Flat, no rete ridges to hold it into the CT so it sloughs away from CT * Striking **_BASAL CELL layer_** - **hyperchromatic & polarized** * Persistence of **crowded basal cells** into **stratum spinosum** * Abrupt transition to **refractile, glassy like parakeratin** with a **corrugated surface** * **Mitotic activity** epithelium is expanding because it wants to
59
How does the histology of Odontogenic Keratocysts (OKC) change when it becomes inflammed? (4)
* _Cyst Lining:_ * **Loses keratin** * **Thickens** * **Loses hyperchromatic basal layer** * Develops **rete ridges** * Resembles other non-descript cysts * Cannot be dx histologically
60
What occurs when an odontogenic keratocyst has keratin? (4)
* More aggressive * Grew bigger * Harder to remove * Recur with a vengance
61
What is the recurrence for Odontogenic Keratocysts? (5)
**30% Recurrence** * _Difficulty in removal_ * _​_The thin epithelium sloughs off as soon as you touch it * Larger ones are multilocular * _Neoplastic potential of remaining epithelium_ * The lining just wants to keep growing * **10 yr follow-up**, it has been known to recur up till 25 yrs * *Higher recurrence than everything except Ameloblastoma (55%)* * *This is the ONLY odontogenic cyst that recurs*
62
What treatment is preferred on larger Odontogenic Keratocysts (OKC)?
**Partsch Procedure** 1. Decompress cyst 2. Curette as much as possible 3. Leave it open to allow drainage 4. Bone begins to fill in and it will be smaller 5. Go back in later on and remove the rest 6. Sterilize peripheral bone *Similar to what is done for Ameloblastoma's*
63
In rare cases what has odontogenic keratocysts transformed into?
* Ameloblastoma * SCCA
64
What are Odontogenic Keratocysts associated with?
Basal Cell Nevus Syndrome
65
What lesion is 10x less common than OKCs and produces ONLY orthokeratin?
Orthokeratinized Odontogenic Cyst
66
What population is most affected by Orthokeratinized Odontogenic Cysts?
**Young-adult, males** (2:1) * *_Lateral Periodontal Cyst_ is the other cyst that prefers males, but they will be \> 40 yrs old*
67
What are 2 characteristics of Orthokeratinized Odontogenic Cysts?
* **2/3** in a **Dentingerous Relationship** * *Mimic a big dentingerous cyst* * **Unilocular**
68
What is the histology of the Orthokeratinized Odontogenic Cyst? (4)
* _Basal Cells_ are: * **Flat** * **Non-proliferative** * **Innocuous** * **Inconspiciuous** ## Footnote *Exact opposite of OKC, whose basal cells are proliferative, polarized, and hyperchromatic*
69
What is the recurrence of Orthokeratinized Odontogenic Cysts?
**2% Recurrence** *Much less aggressive than OKC's (recur in 30%)*
70
What is the etiology of Basal Cell Nevus Syndrome?
**Autosomal Dominant** High penetrance, with variable expressivity Relatively common
71
What are the defining characteristics of Basal Cell Nevus Syndrome? (11)
1. **Multiple BCCA** in **childhood** * Non-sunexposed areas (arms, chest, back) 2. **Multiple OKC's** **​​** 3. **Palmar Pitting** in 65% 4. **Hypertelorism** 5. **Depressed mid-face** 6. **Saddle Nose** - widened nasal bridge 7. Relative **frontal bossing** 8. Relative **mandibular prognathism** 9. **Calcification of falx cerebri** - midline 10. **Bifid ribs** * **​Mental Retardation/Schizophrenia** - some may have Hydrocephalus
72
In Basal Cell Nevus Syndrome what are the skeletal findings due to?
Peripheral resistance to PTH
73
What is the most common finding in the jaws of a pt with Basal Cell Nevus Syndrome?
Multiple OKCs
74
What is the treatment for Basal Cell Nevus Syndrome? (4)
* **Topical Chemotherapy (5 FU)** * Watch for and eliminate BCCA when they 1st occur (superficial, hasn't invaded yet) * If you do not tx BCCA they can become aggressive and coalesce * **Remove OKCs** until they stop developing * **Genetic Couseling** + examination of family members * **Continual Follow-Up** * **​**In rare cases they can develop a ***_Medulloblastoma Brain Tumor_***

Oral Pathology Exam 3 (8 decks)

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