Odontogenic cysts

Question 1

Name 4 common histopathological characteristics of odontogenic cysts

Answer 1

• Non-keratinized stratified squamous epithelial lining (never presence of ameloblast)
• Cyst wall comprised of fibrous connective tissue +/− embedded bone
• Hemorrhage degradation products (hemosiderin and/ or cholesterol crystals)
• Secondary inflammation

Question 2

What is inside the cyst?

Answer 2

serous fluid; hemorrhagic fluid; low numbers of leukocytes; degraded cellular debris hemorrhage-degradation products.

Question 3

Briefly explain how cysts form.

Answer 3

1. Proliferation of the lining epithelium: Stimulation and proliferation of otherwise quiescent odontogenic epithelium by inflammatory mediators or other triggers.
2. Hydrostatic enlargement fluid transport and bone loss are likely to contribute to cyst enlargement.
3. Bone resorption

Question 4

What is the typical presentation of a patient with a dentigerous cyst?

Answer 4

• Dog (often brachycephalic) between 2 and 3 yo with missing tooth (often impacted PM1*, C, I)

Question 5

which breeds are predisposed to dentigerous cysts?

Answer 5

Boxers, Pugs, Shih Tzus

Question 6

Where do dentigerous cysts come from?

Answer 6

Dentigerous cysts arise from a developmental structure – the follicular sac that envelops the crown of an unerupted tooth. The cyst is an expanded tooth follicle space lined by reduced enamel epithelium.

Question 7

what are the characteristics of a lateral periodontal cyst?

Answer 7

• no visible swelling or clinical signs.
• The cyst forms along the lateral root surface of a vital tooth
• usually does not cause tooth displacement
• formed by variable source of residual odontogenic epithelial cells

Question 8

How do radicular cysts form?

Answer 8

• develop from endotoxin and immune stimulation of small odontogenic residues (epithelial rests of Malassez) within periapical tissues of an endodonticaly compromised tooth (non-vital)

Question 9

What are the 2 subtypes of radicular cysts?

Answer 9

• ‘true’ periapical cyst: completely enclosed
• ‘pocket’ periapical cyst: has a cavity confluent with the root canal.

Question 10

How can you differentiate a radicular cyst from a periapical granuloma on x-ray?

Answer 10

They look the same.

Resorption of the affected tooth by a granuloma would be unexpected

Question 11

What is a gingival cyst?

Answer 11

a peripheral version (only gingiva) of the lateral periodontal cyst; develop from sulcus epithelium; often associated with gingival enlargement

Question 12

What are the characteristics of odontogenic keratocyst?

Answer 12

• Aggressive and destructive cyst which has a parakeratinized epithelial lining (developped from rest of Serres)
• Behavior lets think of a tumors (epith. cell replicate, buds, make other cyst lesion, very aggressive)
• Cat, min. schnauzer