Other names:
Adamantinoma
Multilocular cyst
Classification of odontogenic tumours:
Definition of ameloblastoma:
"True benign epithelial odontogenic neoplasm of enamel organ type tissue which does not undergo differentiation to the point of enamel formation."
Robertson:
"Usually unicentric, nonfunctional, intermittent in growth, anatomically benign and clinically persistent."
Note:
- Term adamantinoma: By Malassez
- Term ameloblastoma: By Churchill in 1934
- 2nd most common odontogenic neoplasm after odontoma
- Called odontogenic tumours because it originate through some aberration from the normal pattern of odontogenesis
Pathogenesis:
Stimulus initiating is unknown. The tumour may be derived from:
1. Cell rest of the dental organ
- Cell rest of Serres (dental lamina) or
- Epithelial rest of Malassez (Remnants of HERS)
2. Epithelium of odontogenic cyst (dentigerous cyst) or odontoma
3. Enamel organ development disturbances
4. Basal cells of surface epithelium of jaws
5. Heterotypic epithelium of other parts of body like pituitary
Clinical features:
Age: 10 to 90 years (mostly 30 to 39), 10% in children, M=F
Site: All areas but mandible(80%), molar-angle-ramus area
Race: Common in Asians
- Presenting complaint: Slow growing, painless, bony hard swelling resulting in facial asymmetry
- Large lesions may: mobile teeth, pain and paresthesia
Note:
1. These lesions are locally invasive and may infiltrate medulla causing erosion of cortical bone
2. Peripheral(extraosseous) ameloblastoma:
- Involves soft tissues and overlying alveolar bone
- Cells of origin: Surface epithelium, remnants of dental lamina
- Histologically resembles SCC
3. Pituitary ameloblastoma:
- Craniopharyngioma or Rathke's pouch tumour
Radiographic features:
- Tumour shows compartmented appearance with septa of bone extending into the radiolucent tumour mass
- Periphery of lesion: Smooth and thinning of cortical plates
- Sometimes, displacement of impacted 3d molars
Note:
However, desmoplastic ameloblastoma shows mixed radiolucent-opaque areas with ill defined borders mimicking fibro-osseous lesions
Histologic features:
Six major histologic types: @PicK ABCDeFG
1. Follicular ameloblastoma (Recurrence: 29.5%, heighest)
2. Plexiform ameloblastoma
3. Acanthomatous ameloblastoma (4.5%, least)
4. Granular ameloblastoma
5. Basal cell ameloblastoma
6. Desmoplastic ameloblastoma
Others:
7. Clear cell ameloblastoma
8. Papilliferous ameloblastoma
9. Keratoameloblastoma
10. Hemangiomatous ameloblastoma
Vickers and Gorlin criteria for ameloblastoma:
1. Tall columnar cells
2. Hyperchromatic nuclei
3. Palisaded nuclei
4. Reversed polarity of nuclei
5. Subnuclear vacuole formation
1. Follicular ameloblastoma (most common)
- Central mass of polyhedral, loosely arranged cells resembling stellate reticulum
- Peripheral tall columnar or cuboidal cells resembling
ameloblasts or pre ameloblasts ( Nuclei: hyperchromatic, round or oval, away from basement membrane, palisading pattern)
→Some cases, exhibits tiny cysts (due to breakdown or cystic degeneration of stellate reticulum like tissue) i.e. Cyst formation is common
2. Plexiform ameloblastoma:
- Ameloblasts like tumour cells are arranged in irregular masses or as a network of interconnecting strands of cells
- Each masses or strands is bounded by a layer of columnar cells and between these layers may be found stellate reticulum like cells
3. Acanthomatous ameloblastoma:
- Stellate reticulum undergoes squamous metaplasia, sometimes with keratin formation. So, epithelial or keratin pearls are seen sometimes. (DD : SCC)
4. Granular cell ameloblastoma:
- Marked transformation of stellate reticulum like cells so appear
very coarse, granular, eosinophilic in appearance
- Cytoplasmic granules represent lysosomal aggregates (caused by increased apoptotic cell death in neoplastic cells).
5. Basal cell ameloblastoma: Resembles Basal cell carcinoma (BCC)
6. Desmoplastic ameloblastoma:
- Consists dense collagenous stroma (hyalinized or hypocellular)
- Epithelium is squeezed or fragmented i.e. thin strands or cords of epithelium stretched out in a kite-tail appearance
7. Hemangiomatous ameloblastoma:
- Stroma with blood filled spaces or capillaries
- Etiology: Angiogenesis during tooth development, hamartomatous malformation or trauma
Unicystic ameloblastoma
It is an rare intraosseous ameloblastoma characterized by single cystic sac, with an odontogenic (ameloblastomatous) epithelium.
- Age: 22 years
- Site: Impacted tooth
- Most common provisional diagnosis: Dentigerous cyst
- Prognosis: Better
Vickers and Gorlin histological classification of lining epithelial exhibiting alterations:
1. Luminal unicystic ameloblastoma
2. Luminal and intraluminal unicystic ameloblastoma
3. Luminal, intraluminal and intramural unicystic ameloblastoma
4. Luminal and intramural unicystic ameloblastoma
Important MCQS From Ameloblastoma:
1. Which of the following is called a multilocular cyst?
a. Squamous odontogenic tumour
b. Calcifying epithelial odontogenic tumour
c. Ameloblastoma
d. Adenomatoid odontogenic tumour
Correct answer is c.
2. Adamantinoma is the old name of
a. Squamous odontogenic tumour
b. Calcifying epithelial odontogenic tumour
c. Ameloblastoma
d. Adenomatoid odontogenic tumour
Correct answer is c.
3. Which of the following is called 'anatomically benign and clinically persistent tumour'?
a. Squamous odontogenic tumour
b. Calcifying epithelial odontogenic tumour
c. Ameloblastoma
d. Adenomatoid odontogenic tumour
Correct answer is c.
4. The term 'ameloblastoma' is coined by
a. Malassez
b. Churchill
c. windberg
d. None of the above
Correct answer is b.
5. 4. The term 'adamantinoma' is coined by
a. Malassez
b. Churchill
c. windberg
d. None of the above
Correct answer is a.
a. Ameloblastoma
b. Cementoblastoma
c. Odontoma
d. Ameloblastic fibroma
Correct answer is a.
7. Which of the following is the most common odontogenic tumour?
a. Ameloblastoma
b. Cementoblastoma
c. Odontoma
d. Ameloblastic fibroma
Correct answer is c.
8. The most common site of ameloblastoma is
a. Maxillary anterior region
b. Maxillary posterior region
c. Mandibular anterior region
d. Mandibular posterior region
Correct answer is d.
9. The most common site of ameloblastoma is
a. Mandibular condyle
b. Angle of mandible
c. Body of mandible
d. None of the above
Correct answer is b i.e. Molar-angle-ramus.
10. The most common site of ameloblastoma is
a. Maxillary anteriors
b. Mandibular anteriors
c. Maxillary molars
d. Mandibular molars
Correct answer is d.
11. Peripheral ameloblastoma resembles histologically with:
a. Verrucous carcinoma
b. Squamous cell carcinoma
c. Fibroma
d. Giant cell granuloma
Correct answer is b.
12. Rathke's pouch tumour is
a. Follicular ameloblastoma
b. Plexiform ameloblastoma
c. Peripheral ameloblastoma
d. Pituitary ameloblastoma
Correct answer is d.
13. Soap bubble appearance is the characteristic radiographic feature of:
a. Squamous odontogenic tumour
b. Calcifying epithelial odontogenic tumour
c. Ameloblastoma
d. Adenomatoid odontogenic tumour
Correct answer is c.
14. Which one type of ameloblastoma has most recurrence?
a. Follicular
b. Plexiform
c. desmoplastic
d. Acanthomatous
Correct answer is a.
15. Which one type of ameloblastoma has least recurrence?
a. Follicular
b. Plexiform
c. desmoplastic
d. Acanthomatous
Correct answer is d.
16. Characteristic palisading pattern of nuclei is present in
a. Squamous odontogenic tumour
b. Calcifying epithelial odontogenic tumour
c. Ameloblastoma
d. Adenomatoid odontogenic tumour
Correct answer is c.
17. Cyst formation is relatively common in
a. Follicular ameloblastoma
b. Plexiform ameloblastoma
c. desmoplastic ameloblastoma
d. Acanthomatous ameloblastoma
Correct answer is a.
18. Most common variant of ameloblastoma is
a. Follicular ameloblastoma
b. Plexiform ameloblastoma
c. desmoplastic ameloblastoma
d. Acanthomatous ameloblastoma
Correct answer is a.
19. Keratin pearls can be seen in
a. Follicular ameloblastoma
b. Plexiform ameloblastoma
c. desmoplastic ameloblastoma
d. Acanthomatous ameloblastoma
Correct answer is d.
20. Lysosomal aggregates can be seen in
a. Plexiform ameloblastoma
b. Granular cell ameloblastoma
c. desmoplastic ameloblastoma
d. Acanthomatous ameloblastoma
Correct answer is b.
21. Kite-tail-like appearance is seen in
a. Plexiform ameloblastoma
b. Granular cell ameloblastoma
c. desmoplastic ameloblastoma
d. Acanthomatous ameloblastoma
Correct answer is c.
Important VIVA Questions From Ameloblastoma:
1. Why ameloblastoma is called Adamantinoma?
- Term 'adamantinoma' implies the formation of hard tissue. Malassez believed that hard tissue is present in that lesion but he was wrong. So, later term 'ameloblastoma' is referred by Churchill in 1934.
2. What are the cells of origin of ameloblastoma?
- 1. Cell rest of the dental organ
- Cell rest of Serres (dental lamina) or
- Epithelial rest of Malassez (Remnants of HERS)
2. Epithelium of odontogenic cyst (dentigerous cyst) or odontoma
3. Enamel organ development disturbances
4. Basal cells of surface epithelium of jaws
5. Heterotypic epithelium of other parts of body like pituitary
3. What are the cells of origin of peripheral (extraosseous) ameloblastoma?
- Surface epithelium
- remnants of dental lamina
4. What are the histologic types of ameloblastoma?
- Six major histologic types:
1. Follicular ameloblastoma
2. Plexiform ameloblastoma
3. Acanthomatous ameloblastoma
4. Granular ameloblastoma
5. Basal cell ameloblastoma
6. Desmoplastic ameloblastoma
Others:
7. Clear cell ameloblastoma
8. Papilliferous ameloblastoma
9. Keratoameloblastoma
10. Hemangiomatous ameloblastoma
5. Give four differential diagnosis of ameloblastoma.
a. Odontogenic keratocyst
b. Central giant cell granuloma
c. CEOT
d. Odontogenic myxoma
6. Give three odontogenic tumours that exhibit keratinization
- 1. Acanthomatous ameloblastoma
2. Keratoameloblastoma
3. Papilliferous ameloblastoma
1. Why ameloblastoma is called Adamantinoma?
- Term 'adamantinoma' implies the formation of hard tissue. Malassez believed that hard tissue is present in that lesion but he was wrong. So, later term 'ameloblastoma' is referred by Churchill in 1934.
2. What are the cells of origin of ameloblastoma?
- 1. Cell rest of the dental organ
- Cell rest of Serres (dental lamina) or
- Epithelial rest of Malassez (Remnants of HERS)
2. Epithelium of odontogenic cyst (dentigerous cyst) or odontoma
3. Enamel organ development disturbances
4. Basal cells of surface epithelium of jaws
5. Heterotypic epithelium of other parts of body like pituitary
3. What are the cells of origin of peripheral (extraosseous) ameloblastoma?
- Surface epithelium
- remnants of dental lamina
4. What are the histologic types of ameloblastoma?
- Six major histologic types:
1. Follicular ameloblastoma
2. Plexiform ameloblastoma
3. Acanthomatous ameloblastoma
4. Granular ameloblastoma
5. Basal cell ameloblastoma
6. Desmoplastic ameloblastoma
Others:
7. Clear cell ameloblastoma
8. Papilliferous ameloblastoma
9. Keratoameloblastoma
10. Hemangiomatous ameloblastoma
5. Give four differential diagnosis of ameloblastoma.
a. Odontogenic keratocyst
b. Central giant cell granuloma
c. CEOT
d. Odontogenic myxoma
6. Give three odontogenic tumours that exhibit keratinization
- 1. Acanthomatous ameloblastoma
2. Keratoameloblastoma
3. Papilliferous ameloblastoma
