Final year mds omfs viva question and answer on ameloblastoma

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ameloblastoma AND treatment

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ameloblastoma WHO classification treatment recurrence systematic review 2024

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https://pmc.ncbi.nlm.nih.gov/articles/PMC12829641/

Ameloblastoma: Final-Year MDS OMFS Viva Questions and Answers

1. What is ameloblastoma?

Ameloblastoma is a benign but locally aggressive odontogenic epithelial neoplasm that arises from odontogenic epithelium. It is characterized by slow growth, bone infiltration, cortical expansion/perforation, and a significant tendency for local recurrence if treated inadequately.

2. What is its cell of origin?

Possible sources include:

Rests of dental lamina
Enamel organ
Reduced enamel epithelium
Epithelial lining of odontogenic cysts, especially dentigerous cysts
Basal cells of oral mucosa, particularly in peripheral ameloblastoma

3. What are the current major clinicopathologic types?

The important types are:

Conventional ameloblastoma
- Previously termed solid or multicystic ameloblastoma
Unicystic ameloblastoma
Peripheral or extraosseous ameloblastoma
Metastasizing ameloblastoma

Ameloblastic carcinoma is a separate malignant odontogenic epithelial tumor, showing cytological malignancy.

4. Which type is most common?

Conventional ameloblastoma is the most common type.

5. What is the usual age and site of presentation?

Usually presents in the third to fifth decades
About 80% to 85% occur in the mandible
Most common site: molar-ramus region of mandible
Maxillary lesions often occur in the posterior maxilla and may extend into the maxillary sinus, nasal cavity, orbit, or skull base before detection.

6. What is the usual clinical presentation?

Typical presentation is:

Slow-growing, painless jaw swelling
Facial asymmetry
Buccal and lingual cortical expansion
Tooth displacement, loosening, or mobility
Malocclusion
Root resorption
Paraesthesia is unusual and should raise concern for infection, nerve involvement, or malignancy
Advanced lesions can cause pathological fracture, ulceration, trismus, and extraoral deformity.

7. Describe the radiographic appearance.

Classically, ameloblastoma appears as a well-defined radiolucent lesion which may be:

Unilocular
Multilocular
With a “soap-bubble” or “honeycomb” appearance
Associated with an impacted tooth, especially in unicystic lesions
Associated with root resorption and tooth displacement
Associated with cortical thinning, expansion, perforation, and soft-tissue extension in advanced cases.

A CT scan is preferred for defining bony extent, cortical perforation, and surgical planning. MRI is helpful when there is suspected soft-tissue, marrow, orbital, or skull-base involvement.

8. What are the differential diagnoses of a multilocular radiolucency in the mandible?

Important differentials include:

Odontogenic keratocyst
Odontogenic myxoma
Central giant cell granuloma
Aneurysmal bone cyst
Intraosseous hemangioma
Central odontogenic fibroma
Cherubism, if bilateral/multifocal
Brown tumor of hyperparathyroidism
Intraosseous malignancy in atypical lesions

9. What are the differential diagnoses of a unilocular radiolucency associated with an impacted tooth?

Dentigerous cyst
Unicystic ameloblastoma
Odontogenic keratocyst
Adenomatoid odontogenic tumor
Calcifying odontogenic cyst
Ameloblastic fibroma

Viva point: A dentigerous-cyst-like radiograph does not exclude unicystic ameloblastoma. Histopathology is mandatory.

10. Describe the histopathology of conventional ameloblastoma.

The classic features are:

Islands, cords, or follicles of odontogenic epithelium in a fibrous stroma
Peripheral layer of tall columnar or cuboidal cells
Peripheral palisading
Reverse nuclear polarization, with nuclei away from the basement membrane
Subnuclear vacuolization
Central cells resembling stellate reticulum
Cystic degeneration may be present.

A useful viva phrase is:
“Peripheral palisading with reverse polarization and central stellate-reticulum-like cells.”

11. What is meant by reverse polarization?

In normal ameloblasts, nuclei lie away from the basement membrane. In ameloblastoma, peripheral tumor cells show the same pattern, with nuclei polarized toward the central part of the epithelial island and away from the basement membrane.

12. Name the histological patterns of conventional ameloblastoma.

The common patterns are:

Follicular
Plexiform

Other recognized patterns include:

Acanthomatous
Granular cell
Desmoplastic
Basal cell pattern

These are mainly histologic patterns and usually do not independently dictate treatment. Clinical extent, location, cortical breach, and recurrence are more important surgically.

13. What is follicular ameloblastoma?

It shows discrete epithelial islands or follicles with peripheral palisaded ameloblast-like cells and central stellate-reticulum-like cells. Cystic degeneration within follicles is common.

14. What is plexiform ameloblastoma?

It shows long, interconnecting cords or sheets of odontogenic epithelium in a loosely vascular stroma. The epithelial strands form a network-like or plexiform pattern.

15. What is desmoplastic ameloblastoma?

It is a variant characterized by dense collagenized stroma compressing epithelial islands. Radiographically, it may show a mixed radiolucent-radiopaque appearance and can mimic fibro-osseous lesions. It is often found in the anterior jaws, especially the maxilla.

16. What is unicystic ameloblastoma?

Unicystic ameloblastoma is a cystic lesion in which the cyst lining shows ameloblastomatous epithelium, with or without intraluminal and mural tumor proliferation. It often occurs in younger patients and may mimic a dentigerous cyst.

Histologic subtypes:

Luminal
Intraluminal
Mural

17. Why is the mural subtype important?

Mural unicystic ameloblastoma has tumor infiltration into the cyst wall. It has a higher recurrence risk after simple enucleation than pure luminal or intraluminal lesions, so management is generally more aggressive, often with resection depending on extent and patient factors.

18. What is peripheral ameloblastoma?

Peripheral ameloblastoma is an extraosseous lesion arising in the gingiva or alveolar mucosa. It usually presents as a painless gingival nodule in middle-aged adults. It is usually less aggressive than intraosseous ameloblastoma.

Treatment: Local excision down to periosteum, with removal of superficial “cupping” bone if involved, followed by surveillance.

19. What is metastasizing ameloblastoma?

It is a histologically benign-appearing ameloblastoma that metastasizes, most commonly to:

Lungs
Cervical lymph nodes
Bone
Pleura

The primary and metastatic lesions may appear histologically benign. Diagnosis is made by the presence of metastasis, not by histological atypia.

20. Differentiate ameloblastoma from ameloblastic carcinoma.

Feature	Ameloblastoma	Ameloblastic carcinoma
Biological behavior	Benign but locally aggressive	Malignant
Cytology	Usually bland	Cytological atypia
Mitoses	Low	Increased, often atypical
Necrosis	Usually absent	May be present
Invasion	Local bone infiltration	Local destruction with malignant features
Metastasis	Rare, only in metastasizing type	May metastasize
Treatment	Complete surgical resection	Wide resection, staging, selective adjuvant therapy

Features suggesting ameloblastic carcinoma include marked cellular pleomorphism, hyperchromatism, increased mitoses, atypical mitoses, necrosis, and destructive invasion.

21. What investigations would you order?

A practical OMFS work-up:

OPG
- Initial assessment of lesion site, teeth, roots, and mandibular continuity.
CT scan with bone windows
- Defines cortical expansion/perforation, extent in ramus/condyle, and relation to inferior alveolar canal.
Contrast-enhanced CT or MRI
- If soft-tissue extension, maxillary lesion, orbital/nasal/skull-base extension, or recurrent disease is suspected.
Incisional biopsy
- Essential for diagnosis and planning.
- Obtain an adequate deep representative sample.
- Avoid relying on cyst lining alone in a large lesion, because mural invasion may be missed.
Chest imaging
- Consider in metastasizing ameloblastoma or suspected malignant disease.
Molecular testing
- Consider for recurrent, unresectable, metastatic, or advanced lesions where targeted therapy may be relevant.

22. What are the common molecular alterations?

The most important pathway is the MAPK pathway.

BRAF V600E mutation is common, especially in mandibular conventional ameloblastoma.
SMO mutations are more often associated with maxillary tumors.
Other reported alterations involve RAS, FGFR2, and related MAPK-pathway genes.

This is clinically relevant in recurrent or unresectable disease because BRAF-directed therapy may be considered after molecular confirmation. A 2024 systematic review of targeted therapies supports the emerging role of targeted treatment, but surgery remains the standard definitive treatment for resectable disease.

23. What is the treatment of conventional ameloblastoma?

The standard principle is complete surgical excision with a bony margin, because the tumor infiltrates cancellous bone beyond its visible radiographic boundary.

For most conventional intraosseous ameloblastomas:

Marginal resection may be considered in selected lesions when the inferior border is uninvolved and an adequate margin can be achieved.
Segmental mandibulectomy is indicated when there is extensive medullary involvement, inferior-border involvement, pathological fracture, cortical perforation with major soft-tissue extension, or recurrence.
A commonly quoted margin is approximately 1 cm beyond the radiographic extent, adjusted for anatomy and tumor spread.
Immediate reconstruction is usually preferred when a segmental defect is created.

Simple curettage or enucleation of a conventional solid/multicystic lesion is generally associated with unacceptable recurrence risk.

24. How do you treat ameloblastoma in the maxilla?

Maxillary ameloblastoma should be treated more cautiously because:

Maxillary bone is thin and cancellous.
Tumor can spread silently into the maxillary sinus, nasal cavity, pterygopalatine region, orbit, or skull base.
Radiographic margins may underestimate true extent.

Treatment usually requires wide resection, such as partial maxillectomy, tailored to the anatomic extent. Long-term imaging follow-up is required.

25. How do you manage unicystic ameloblastoma?

Management depends on subtype, size, site, patient age, and mural invasion.

Luminal/intraluminal UA: enucleation with careful curettage may be considered in selected cases, particularly in young patients.
Large lesions: decompression or marsupialization may be used initially to reduce size, followed by definitive surgery.
Mural UA: often requires resection or a more aggressive approach because of infiltration into the fibrous wall.
Long-term clinical and radiographic follow-up is mandatory.

A recent review found that recurrence after unicystic ameloblastoma treatment may occur years later, supporting prolonged surveillance rather than short follow-up alone. See the 2025 systematic review.

26. Is radiotherapy indicated?

Radiotherapy is not routine treatment for resectable ameloblastoma because surgery offers better local control and these tumors are traditionally considered relatively radioresistant.

It may occasionally be considered in highly selected situations, such as:

Unresectable disease
Residual disease when further surgery is not feasible
Palliation
Selected malignant lesions, as part of multidisciplinary care

27. Is chemotherapy useful?

Conventional cytotoxic chemotherapy has no established routine role in resectable conventional ameloblastoma.

For recurrent, unresectable, metastatic, or selected malignant tumors, targeted therapy based on actionable mutations, especially BRAF V600E, may be considered in a multidisciplinary tumor board setting.

28. What reconstruction options are available after mandibulectomy?

Choice depends on defect size, soft tissue loss, dentition, and patient factors.

Options include:

Reconstruction plate
Non-vascularized iliac crest graft in selected small defects
Free fibula flap, commonly preferred for long segmental defects
Iliac crest free flap
Scapular or DCIA free flap
Secondary dental rehabilitation with implants where appropriate

For a young patient with a large mandibular defect, the standard viva answer is often:
“Segmental resection with immediate vascularized fibula free-flap reconstruction.”

29. What are the recurrence rates and follow-up protocol?

Recurrence depends heavily on lesion type and treatment method.

Conventional ameloblastoma treated conservatively has a high recurrence risk.
Recurrence can occur many years after apparently complete treatment.
Recurrences are frequently seen within the first 5 years, but late recurrence occurs.

Follow-up approach:

Clinical examination and OPG/CT as indicated
More frequent review in the first 2 to 5 years
Continued long-term, often lifelong, surveillance for conventional, recurrent, maxillary, or aggressive lesions.

30. Give a 30-second viva answer on management.

“Ameloblastoma is a benign but locally aggressive odontogenic epithelial tumor, most commonly affecting the posterior mandible. Diagnosis is made by imaging and incisional biopsy. Conventional intraosseous ameloblastoma should usually be treated by complete surgical resection with an adequate bony margin, often about 1 cm beyond radiographic extent, followed by reconstruction where required. Unicystic lesions may be managed more conservatively in selected luminal or intraluminal cases, but mural disease requires more aggressive treatment. Maxillary lesions need particular caution because of early spread into adjacent spaces. Long-term, often lifelong, clinical and radiographic surveillance is required because recurrence may occur late.”

Common Viva Traps

“Is it benign?”
Histologically benign, but clinically locally aggressive and infiltrative.
“Can you treat conventional ameloblastoma by simple enucleation?”
Generally no. It has high recurrence risk because of microscopic infiltration beyond the apparent lesion.
“Does a dentigerous-cyst-like appearance rule out ameloblastoma?”
No. Unicystic ameloblastoma may mimic a dentigerous cyst.
“Does metastasizing ameloblastoma look malignant histologically?”
Not necessarily. It may appear benign histologically despite metastasis.
“What is the key microscopic feature?”
Peripheral palisading, reverse nuclear polarization, and central stellate-reticulum-like cells.
“What mutation should you remember?”
BRAF V600E, particularly in mandibular conventional ameloblastoma.

Textbook basis: K. J. Lee’s Essential Otolaryngology, section “Ameloblastoma”; Cummings Otolaryngology Head and Neck Surgery, sections on ameloblastoma and unicystic ameloblastoma.

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