Tuesday, 28 April 2015

Odontogenic Neoplasm : Ameloblastoma


Ameloblastoma is a locally agressive neoplasm arising from the odontogenic epithelium and it is the most common odontogenic neoplasm of the oral cavity.


Amel = enamel
Blastos = germ

The name ameloblastoma was given by Ivey and churchill in the year 1934.


ETIOLOGY 



Exact etiology is unknown but these are the predisposing factors:-


  • Trauma
  • Infection
  • Previous Inflammation
  • Extraction of tooth
  • Dietary factors
  • Viral Infection

PATHOGENESIS



Exact cell of origin is unknown but it possibly arises from the following:-

  • Enamel Organ of developing tooth germ.
  • Cell rest of Serre (remnants of dental lamina).
  • Epithelial lining of odontogenic cyst (especially the dentigerous cyst).
  • Oral epithelium (basal cell layer) (rarely).
  • REE (reduced enamel epithelium)
  • Cell rest of Malassez.

CLINICAL FEATURES



Incidence : 1% of all oral tumors.
                 18% of all odontogenic tumors.

Age :         II, III, IV, V decade of life.
                 mean age of occurance is 32 years.

Race :       Blacks > White      

Sex :        M > F

Site :        Mandible = 80 % (especially in molar ramus area).
               Maxilla = 20 %
              
Extraosseous or peripheral ameloblastomas can rarely occur mostly in relation to the gingiva.


TYPES

     
  • Unicystic
  • Multicystic
  • Peripheral
  • Malignant


CLINICAL PRESENTATION


  • Slow enlarging
  • Painless
  • Ovoid
  • Bony hard swelling
  • Lesion caused expansion and distortion of the cortical plates of the jawbone and displacement of the regional teeth which leads to gross facial asymmetry.
  • Pain, paresthesia and mobility of the regional teeth may be present.
  • Egg shell crackling.
  • Mucosa overlying is normal
  • Tooth of the involved region are vital.
  • Small lesion may remain aymptomatic for long duration of time.
  • Detected incidentally during routine examination.
  • Large lesion may perforate the cortical plates.
  • Maxillary tumor may invade the maxillary air sinus and further upto the orbit or the nasopharynx.

RADIOGRAPHIC FEATURES


  • Well defined, multilocular, radiolucent area in bone.
  • Honey Comb or Soap Bubble appearance.
  • Few lesions are unilocular.
  • Larger lesion may cause expansion or perforation of buccal and lingual cortical plates.
  • Irregular or scalloped margin.

DIFFERENTIAL DIAGNOSIS


  1. Dentigerous cyst.
  2. Odontogenic keratocyst.
  3. Central giant cell granuloma.
  4. Aneurysmal bone cyst.
  5. Pindborg's tumor.

Macroscopic Features


  • Egg shell cracking
  • Greyish white or greyish yellow.
  • May contain straw coloured fluid.
  • Sometimes tooth may be present within the lesion.


TREATMENT


Surgical enucleation of the tumor and thorough curettage og surrounding bone. Recurrence is common. Sometimes radical surgical approach may have to be adopted in cases of repeated recurrence. Some tumors may cause distant metastasis.


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