Tumor like cyst

Site

• Commonly maxilla
• Mandible – premolar region

Radiology

• 1/4 of these cysts are peripheral, radiographically evident calcification, above underlying cortex and manifest as gingival swellings
• Well defined unilocular/multilocular radiolucency
• 50% have opaque foci in “salt and pepper” pattern
• 33% associated with unerupted teeth
• Root resorption and divergence

Histology

• Cystic lesion + fibrous capsule + epithelial lining 4-10 cells
• Basal cells cuboid/columnar
• Overlying epithelium resembles stellate reticulum
• Ghost cells – Eosinophilic, anucleate epithelial cells that have undergone dystrophic calcification

Management

• Simple surgical excision
• Good prognosis

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Neoplasm of both odontogenic epithelium and mesenchyme

Etiology

• Associated with impacted teeth

Clinical

• Slow growing
• Asymptomatic
• Expand jaw

Epidemiology

• Young adults and children

Common site

• Maxilla > Mandible
• Mandible – Molar ramus area

Radiology

• Well circumscribed lesion – surrounded by sclerotic margin
• Unilocular/multilocular
• Associated with crown of impacted teeth
• Radiolucent
• Opaque foci indicates progression to ameloblastic fibro-odontoma

Histology

• Neoplastic odontogenic epithelium + myxomatous CT = resembles dental lamina
• Encapsulated with collagenous tissue
• In fibro-odontoma/dentinoma – hard tissue formation

Management

• Surgical curettage/excision
• Can become malignant – Ameloblastic fibrosarcoma

Difference between ameloblastic fibroma and ameloblastoma

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Ameloblastic fibrosarcoma

• Rare malignant variant that can arise from pre-existing ameloblastic fibroma
• Mandible > Maxilla
• Clinical: Pain & parasthesia
• Management: Resection
• Malignancy is locally aggressive with metastatic potential

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Odontoameloblastoma

• Ameloblastoma that secretes dental hard tissues

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Two third tumor

• 2/3 in female
• 2/3 in maxilla
• 2/3 anterior jaw
• 2/3 associated with the crown of an impacted tooth

Clinical

• Slow growth
• Asymptomatic

Radiology

• Well defined unilocular lesion – surround crown of an unerupted/impacted tooth
• Radiolucent but small foci of radiopacity
• Expansive but not invasive
• Divergence of roots

Histology

• Intracystic epithelial proliferation – composed of polyhedral/spindle cells forming lobular patterns or syncytia
• Rosettes and duct like structures of columnar epithelial cells
• Small foci of calcification, sheets of epithelial cells around microcyst
• Positive stain: PAS

Management

• Conservative treatment – Enucleation
• Don’t recur – benign and encapsulated

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Histiogenesis

• Proliferation of odontogenic epithelium – arise from rest cells of Malassez

Site

• Maxilla – Incisor canine area
• Mandible – Molar area

Clinical

• Unifocal
• Tooth mobility
• Multiple lesions in 20% affected patient

Radiology

• Well circumscribed lesion
• Semilunar in cervical region of roots of teeth
• Root divergence
• Calcification – cause development of a target lesion (opaque with circumferential lucent halo)

Management

• Curettage/excision

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• Pindborg tumor
• Aggressive odontogenic neoplasm, associated with an impacted/unerupted tooth
• The only odontogenic tumor to contain amyloid

Histiogenesis

• REE
• Stratum intermedium
• Dental lamina

Site

• Mandible : Maxilla = 2 : 1
• Mandible – Body/ramus
• Gingiva as peripheral tumor

Clinical

• Widening of follicular spaces
• Failure of involved tooth to erupt
• No pain
• Incidental finding on routine radiograph
• Locally infiltrative, not metastasize

Radiology

• Expanded cortices in buccal, lingual and vertical dimensions
• Radiolucency + poorly defined, non cortical borders
• Early: unilocular, multilocular
• Late: “Driven snow appearance”
• Root divergence and resorption
• Impacted tooth displaced with arrested root development

Histology

1. Microsheets of polyhedral, eosinophilic squamous epithelial cells with:

• Focal psammoma bodies (single cell calcifications)
• Concentric calcific deposits (Liesegang rings in amyloid responsible for radiopacities)

2. Tumor cells are:

• Polygonal
• With dysmorphic nuclei
• Interspersed with amyloid deposits
• Containing degenerated keratin filaments

3. Scanty stroma + clear cell variant has clear vacuolated cytoplasm

4. Positive stains: Keratin, Congo red, Thioflavin T for amyloid

Management

• Enucleation for clearly circumscribed early lesion
• Excision with margin – Advanced multilocular/invasive lesions

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Clinical

• Ulceration and jaw swelling
• Progressive jaw pain
• Rare: Trismus, dysphonia

Management

• Radical surgical resection + neck dissection
• Follow up to avid recurrence

NB:

• Metastasis to lungs, liver, lymph nodes, kidney, spleen, skull, skin
• Initially: Similar to ameloblastoma
• Late: Similar to OSCC

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• Most common odontogenic tumor
• Benign
• Locally invasive

Clinicopathological subtypes

1. Solid/multicystic
2. Unicystic
3. Desmoplastic
4. Peripheral/extraosseous

Etiology

• Unknown – Trauma, inflammation, infection

Epidemiology

• 4th-5th decade
• M = F

Site

• Mandible : Maxilla = 4 : 1
• Mandible sites:
  • 70% molar ramus area
  • 20% premolar region
  • 10% incisor region

Clinical

• Slow growing
• Asymptomatic
• Gradual facial deformity and jaw expansion
• Bony hard, non tender ovoid swelling
• Egg shell crackling of bones on palpation in advanced cases
• Late feature: Perforation of bone + spread into soft tissue
• In maxilla – Expansion in sinus may mask true size of tumor

NB: Locally invasive but not metastasize

Diagnosis

• Incisional biopsy
• Radiology:
  • Usually multilocular, unilocular
  • Roots of associated teeth resorbed
  • Associated with unerupted teeth – particularly lower 8 (mimic dentigerous cyst)

Differential diagnosis

• Dentigerous cyst
• Odontogenic myxoma
• KCOT
• CEOT
• CCOT
• AOT

Pathogenesis

Main source of epithelium:

• Enamel organ
• Rests of Malassez
• Rests of Serres
• REE
• Lining of odontogenic cysts

Mechanism of growth and invasion:

• Overexpression of anti-apoptotic proteins – Bcl₂, Bcl_x
• Interface proteins enhance invasive properties – FGF, IL-1, IL-6, MMPs
• P53 downregulated

Histology

• Reversed nuclei polarity
• Tall columnar cells on periphery (ameloblasts)

Classification:

1. Follicular – Discrete, rounded islands or follicles, resemble enamel organ
2. Plexiform – Tangled mass of network of anastomosing strands + irregular masses
3. Acanthomatous – Squamous metaplasia and keratinization of stellate reticulum, keratin pearls
4. Desmoplastic – Extensive fibrosis of interstitial tissue, often anterior mandible
5. Cystic – Large cystic spaces lined by thin epithelium with basal palisading
6. Granular – Central, neoplastic cells – exhibit prominent cytoplasmic granularity
7. Basaloid – Similar to basal cell carcinoma

Management

• Surgical excision with margin of 1.5-2cm of normal bone
• + Reconstruction (Mandible – Titanium/stainless steel, Maxilla – Obturator)
• Good prognosis
• Can recur

Difference between ameloblastoma and ameloblastic fibroma

Ameloblastic fibroma	Ameloblastoma
Younger (1st and 2nd decade)	Older (4th and 5th decade)
Encapsulated	Non encapsulated
Inductive margin	No inductive margin
Not invasive	Invasive
Mixed: Epithelial and mesenchymal tissues	Odontogenic epithelium
Conservative – wide excision	Wide excision (1.5-2cm bone)
1 histologic subtype	7 histological subtypes
Common in maxilla	Common in mandible

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Arising from remnants of tooth development

Benign tumors

A) Odontogenic epithelium, without odontogenic ectomesenchyme

1. Ameloblastoma
2. Calcifying epithelial odontogenic tumor (Pindborg tumor) (CEOT)
3. Squamous odontogenic tumor (SOT)
4. Adenomatoid odontogenic tumor (AOT)
5. Keratocystic odontogenic tumor (KCOT)

B) Odontogenic epithelium + odontogenic ectomesenchyme ± dental hard tissue formation

1. Ameloblastic fibroma
2. Ameloblastic fibrodentinoma & ameloblastic fibro-odontoma
3. Odontoameloblastoma
4. Calcifying cystic odontogenic tumor (Gorlin cyst)
5. Odontoma

C) Odontogenic ectomesenchyme ± odontogenic epithelium

1. Odontogenic fibroma
2. Myxoma (odontogenic myxoma, myxofibroma)
3. Cementoblastoma

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Malignant tumor

A) Odontogenic carcinoma (epithelial origin)

1. Ameloblastic carcinoma
2. Primary intraosseous squamous cell carcinoma
3. Clear cell odontogenic carcinoma
4. Ghost cell odontogenic carcinoma

B) Odontogenic sarcoma (mesenchymal origin)

1. Ameloblastic fibrosarcoma
2. Ameloblastic fibro-dentinosarcoma
3. Ameloblastic fibro-odontosarcoma

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Bone related lesions

1. Ossifying fibroma (cemento ossifying fibroma)
2. Fibrous dysplasia of bone
3. Osseous dysplasia (cemento osseous dysplasia)
   • Focal COD
   • Periapical COD
   • Florid COD
4. Central giant cell lesion
5. Cherubism
6. Aneurysmal bone cyst
7. Simple bone cyst (solitary, traumatic, hemorrhagic)

• Rare osteoclastic and pigmented neoplasm, primarily affects jaws of infants
• Rapidly growing neoplasm
• Presents in first 4 months after birth
• M : F = 6 : 7

Site:

• Maxilla (common)
• Mandible
• Rare: Skull, long bones, epididymis, mediastinum

Clinical: Expanding blue-black lesion – causes facial asymmetry – displacement of lip and alter base of nose + destruction of alveolar bone

Pathology:

• Arise from neural crest cells associated with tooth germ
• Malignancy rare
• Can recur

Radiology: Multiple areas of radiolucency – associated with displacing teeth

Histology: Neuroblasts + pigment containing cells forming ducts and tubules

Diagnosis:

• FNA
• VMA (Vanillylmandelic acid) – monitor recurrence

Differential diagnosis:

• Myoblastoma
• Teratoma
• Vascular tumor
• Rhabdomyosarcoma

Management: Surgical excision (15-20% recurrence)

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Well demarcated/encapsulated solitary neural tumor

Etiology: Proliferation of cells of nucleated sheath of Schwann

Histology: Schwann cells + fibroblasts + collagen/ground substance

• Antoni A: Parallel arrays of collagen fibers & spindle cells + palisaded nuclei
• Antoni B: Disorderly cells & collagen fibers – in mucinous microcystic stroma

No treatment to avoid further damage, regular check ups

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