3. Odontogenic Tumors Flashcards
What is the most common Epithelial Odontogenic Tumor?
Ameloblastoma
(11% of odontogenic tumors)
What is the other name for Ameloblastoma?
Adamantinoma
What population is affected by Ameloblastomas?
No one is immune
- Most cases arise on or after 3rd - 4th decade
- But can occur in younger individuals
- Equal M:F
Where are Ameloblastomas located from most to least frequently?
- Posterior Mandible (77%)
- Anterior Mandible (10%)
- Posterior Maxilla (7%)
- Anterior Maxilla (6%)
What is the clinical presentation of all Epithelial Odontogenic Tumors?
- Slow growing
- Painless
- Bony hard swelling
What is the CLASSIC radiographic appearance of an Ameloblastoma? (5)
- Multilocular RL, without RO
- Fusiform/tapered mass due to expansion
-
“Eggshell” thin cortex
- As it grows it eats away the cortex
- If advanced it can perforate the cortex
- Can displace teeth + resorb roots (80%)
- Associated with an impacted tooth, usually 3rd molar (77% mandibular)
What is the histology of an Ameloblastoma? (3 zones)
-
Peripheral Zone - Hyperchromatic columnar ameloblasts “piano keys” with:
-
Subnuclear vacuolization
- Bubbly appearing cytoplasm - defines an ameloblast
- Reverse polarity of nuclei (toward center not CT)
-
Subnuclear vacuolization
- Central Zone - of Stellate Reticulum
-
Outer Zone - of supporting stroma
- Mature, collagen producing CT, not neoplastic
What does an Ameloblastoma’s histology reproduce?
Early Enamel Organ
Not going to see enamel forming because they are neoplastic ameloblasts and enamel has to have dentin first to form.
Where are the changes occuring in the different histologic variations of Ameloblastoma?
Stellate Reticulum
Doesn’t change the way it behaves or the prognosis
Which Histologic Variation of Ameloblastoma is the conventional type?
Follicular Ameloblastoma
Which Histologic Variation of Ameloblastoma is misken for SCCA, showing invading islands of squamous metaplasia within the SR?
Acanthomatous Ameloblastoma
In which Histologic Variation of Ameloblastoma does the SR develop cells with a granular appearance?
Granular Cell Ameloblastoma
Not the same cell as a granular cell tumor or congenital epulis
Which Histologic Variation of Ameloblastoma has no SR, it just looks like a proliferation of dental lamina that hasn’t matured to the appearance of an enamel organ?
Plexiform Ameloblastoma
Which Histologic Variation of Ameloblastoma is mistaken for Metastatic Cancers and Salivary Gland Tumors?
Plexiform Ameloblastoma
What histologically occurs in Desmoplastic Ameloblastoma?
- Cells of a tumor cause the CT to become fibrous, collagenous, and dense
- The dense CT squeezes the epithelial component
Where does a Desmoplastic Ameloblastoma occur?
Anterior Maxilla
Least common area for an Ameloblastoma
How is the radiographic appearance of a Desmoplastic Ameloblastoma different from the Follicular type?
NOT Purely RL
- Has some “ground glass” opacification
- Only variant with RO
- Due to dense collagen production
What is the histogenesis of Ameloblastomas? (3)
- Originate from residual pluripotential dental lamina rests, developing enamel organ, or the lining of Dentingerous Cyst
- The cells are primitive with unrestrained growth
- They are not capable of inducing dentin or production of enamel
What other lesions do Ameloblastoma’s have a relationship with? (5)
- Basal Cell Carinoma
- Tibial Adamanthinoma
- Craniopharyngioma
- Peripheral Ameloblastoma
- Unicystic Ameloblastoma
What does a Tibial Adamanthinoma histologicall resemble?
Plexiform Ameloblastoma
But it is a malignant tumor derived from sweat glands
Why does a Craniopharyngioma precisely resemble the histo of an Ameloblastoma?
Ameloblastoma of the Pituitary Area
- It is derived from the craniopharyngeal duct from the posterior stomodeum (oral cavity) that goes upward to form the pituitary
- The surround tissue will be brain tissue, not collagen
What characterisizes the appearance of a Peripheral Ameloblastoma?
- Ameloblastoma arising in the gingiva WITHOUT primary bone involvement
- It may erode and secondarily infect bone, causing a slight RL.
- Produces a GUM BUMP (4 common in DD)
Where does a peripheral ameloblastoma arise from?
Soft tissue lesion, arising from surface epithelium
What is included in the DD for a Peripheral Ameloblastoma?
Gum Bumps
- Pyogenic Granuloma
- Peripheral Giant Cell Granuloma
- Fibroma/Fibrous Hyperplasia
- Peripheral Ossifying Fibroma
What is the treatment and prognosis for a Peripheral Ameloblastoma?
- Doesn’t act like a typical AB, it isn’t as nasty, and it isn’t very aggressive
-
Recurrence in ~17%
- Can be cured by a wider re-excision
- Recurrences must be removed
What is the histology of the Peripheral AB?
Can look like any normal subtype of AB
What is the Histogenesis of a Unicystic Ameloblastoma?
- Arises as a cyst whose lining shows:
- SR over a basal layer of hyperchromatic ameloblasts
- Not infiltrative like AB
What is the population affected by Unicystic AB?
Peaks in teenagers
Typical AB is 3rd-4th decade
Where are Unicystic ABs formed?
90% form around the crown of an unerupted mandibular molar
What is the radiographic appearance of a Unicystic AB?
-
Unilocular, well-demarcated RL
- Not multilocular like AB
- Symmetrical like a “big egg”
- Hyper-ostotic border around periphery
- Can get enormous, but is slow to invade
- Can take up entire ramus and thin out the mandible
What is the prognosis of a Unicystic AB?
30% recurrence with curettage
What are the characteristics of Ameloblastic Carcinoma? (3)
- Histo shows a growth pattern like AB but, the cells are:
- Pleomorphic
- High mitotic activity
- Fast growth
- Metastasize
- RL lesions
What are the characteristics of Malignant Ameloblastoma? (2)
- Perfectly benign histology
- But metastasizes to lungs
- This is the only way to dx it
What is the prognosis for Ameloblastoma?
- Aggressive and recurs in 55% of attempted cures, no matter what tx method was used
- > 5 yrs follow-up needed, because they are slow growing
-
Maxillary = more aggressive
- Can be mutilating and impossible to tx if it spreads from the ethmoid’s –> sinus –> brain
What is the rule for treating an Ameloblastoma of the Mandible?
-
Marginal Resection
- Resect 1 cm of radiographically normal cancellous bone and SPARE CORTEX if not involved
- Leave the integrity of the bone
-
Segemental Block Resection
- Perforated cortex mandates this
- Lose continuity of mandible
- Some may prefer to currete mandibular tumors, yeilding a smaller marginal resection
What is the rule for treating an Ameloblastoma of the Posterior Maxilla?
- NEVER Curettage because recurrence is inevittable and unmanageable
- Must resect with wide margin up to and including hemi-maxillectomy
Why is the Adenomatoid Odontogenic Tumor (Adenoameloblastoma) called the 2/3rds tumor?
- 2/3 Female
-
2/3 Maxilla (mostly anterior)
- Never past premolar region
-
2/3 10-20 y.o.
- Not seen past the age of 25