Ameloblastoma (most frequent Odontogenic Tumor)
Ameloblastoma (from the early English word amel, meaning enamel + the Greek word blastos, meaning germ) is a rare, benign tumor of odontogenic epithelium (ameloblasts, or outside portion, of the teeth during development) much more commonly appearing in the mandible than the maxilla.
Clinically seen 1st by CUSAK (1827) Though he wasn’t able to diagnose it completely.
Previously called ADAMANTIOMA by French Scientist Charles Malassez.
Finally named AMELOBLASTOMA (1927) by Ivey and Churchill.
1.Conventional Multicystic Solid (86 % of all cases).
2. Unicystic ( 10 % of all cases).
3. Extraosseous (1% of all cases).
These tumours are mostly BENIGN i.e. they hardly spread to other parts of the body. These tumours are usually asymptomatic and exhibit a very slow growth pattern. So many a times they are neglected by patients until it reaches a massive size causing gross abnormalities of face and jaws.
Radiographic Feature : Multilocular Radiolucent Lesion
Larger Loculations >>> SOAP BUBBLE Appearance .
Smaller Loculations >>> HONEY COMB Appearance .
Clinical Features : Rare in children .Most active in later decades of life i.e 6th to 7th decade. But in some few exceptions have been seen in youger people.
LOCATION >>> Most Commonly in Mandible (3rd molar region)
85% in the mandible posterior part
15 % in the maxillary posterior part.
Asymptomatic, Painless & no paresthesia.
N.B .. DESMOPLASTIC AMELOBLASTOMA ( a variety with marked predilection to occur in the anterior regions of the jaw usually in maxilla).
Histopathology will show cells that have the tendency to move the nucleus away from the basement membrane. This process is referred to as “Reverse Polarization”
Variants >>> Follicular & Plexiform ( Most Commom Clinically)
acanthomatus,desmoplastic,granular & basal.
FOLLICULAR >>> The follicular type will have outer arrangement of columnar or palisaded ameloblast like cells and inner zone of triangular shaped cells resembling stellate reticulum in bell stage. The central cells sometimes degenerate to form central microcysts.
PLEXIFORM >>> The plexiform type has epithelium that proliferates in a “Fish Net Pattern”. The plexiform ameloblastoma shows epithelium proliferating in a ‘cord like fashion’, hence the name ‘plexiform’. There are layers of cells in between the proliferating epithelium with a well-formed desmosomal junctions, simulating spindle cell layers.
ACANTHOMATOUS>>> Squamous Metaplesia , Keratin Formation , Islands of Follicular Ameloblastoma.
GRANULAR CELL TYPE >>> Lesional epithelial cells resemble granular cells. These cells resemble Lysosomes structurally.
DESMOPLASTIC PATTERN >>> Small islands of odontogenic epithelium ususlly having Tranforming Growth Factor B.
BASAL CELL PATTERN >>> Least common type . Nests of uniform basaloid cells.
While chemotherapy, radiation therapy, curettage and liquid nitrogen have been effective in some cases of ameloblastoma, surgical resection or enucleation remains the most definitive treatment for this condition
Because of the invasive nature of the growth, excision of normal tissue near the tumor margin is often required
While not a cancer that actually invades adjacent tissues, ameloblastoma is suspected to spread to adjacent areas of the jaw bone via marrow space. Thus, wide surgical margins that are clear of disease are required for a good prognosis. This is very much like surgical treatment of cancer. Often, treatment requires excision of entire portions of the jaw.
Recurrence is common, although the recurrence rates for block resection followed by bone graft are lower than those of enucleation and curettage.
Follicular pattern recurrences most commonly.
Persistent follow-up examination is essential for managing ameloblastoma.Follow up should occur at regular intervals for at least 10 years. Follow up is important, because 50% of all recurrences occur within 5 years postoperatively.
DISCLAIMER : Photos have been collected randomly for the purpose of explaining the medical condition. The author does not claim any ownership over the pictures.