Ameloblastoma natural history, complications and prognosis
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Simrat Sarai, M.D. [2]
Overview
Depending on the extent of the tumor at the time of diagnosis, the prognosis may vary. However, the prognosis is generally regarded as poor/good/excellent.
Natural History, Complications, and Prognosis
Natural History
- In several cases the patients with ameloblastoma are asymptomatic.[1][2]
- Ameloblastoma most commonly diagnosed as an accidental finding on orthopantomography.
- The most common symptoms in patients with ameloblastoma are
- Facial swelling
- Malocclusion
- loosening of teeth
- Ill-fitting dentures
- Periodontal diseases
- Oroantral fistulas and
- Nasal airway obstruction
- Ameloblastoma is regarded as a true neoplasm of enamel.
- Ameloblastoma described as unicentric, nonfunctional, intermittent in growth.
- Ameloblastoma is the second most common odontogenic neoplasm.
- Ameloblastoma histologically classified as six subtypes:
- Follicular subtype
- Plexiform subtype
- Acanthomatous subtype
- Granular subtype
- Desmoplastic subtype and
- Basilar subtype.
- Ameloblastoma most commonly affects mandible more than maxilla.
- Ameloblastomal progress as a slow growing, painless expansion of jaw
Complications
Complications of ameloblastoma include the following:
- Breathing difficulty.
- Pain and facial deformity.
- Secondary infection of the tumor.
- The recurrence rate of these tumors is 25-30%.
Prognosis
- The prognosis of ameloblastoma was associated mainly with the method of surgical treatment, which means that patients receiving a radical treatment had a better prognosis than those who received a radical one. It seemed that the best way for treating the ameloblastoma was extensive resection of the tumor with a wide region in the normal bone.
In majority of patients the radical surgery is a best choice, but not for all. In more than 50% patients receiving the conservative treatment had good prognosis without any recurrence. In other words, more than 50% patients could be treated by a conservative method, and maintain the continuity of their jaws to have a better quality of life.
- Many factors were related with the prognosis of ameloblastoma.
- It is valid to use radiographs to estimate the growth rate of focal osseous lesions in clinical practice. The biological behavior of the ameloblastoma was related to the radiographic appearance, and the multilocular type of ameloblastoma had a poor prognosis. The radiographic boundary of ameloblastoma is a useful parameter in evaluating the growth rate of the tumor. Scientists have also stated that, while ameloblastomas invaded the intertrabecular spaces of cancellous bone, they do not invade compact bone, although they may erode it. Ameloblastoma which has a well-defined edge with sclerosis is thought to grow slowly, and the normal bone has a strong reaction to form the sclerosis edge, which acts like compact bone to resist the invasion of the tumor, even if the size of the lesion is comparably large. So the tumor is confined and the prognosis is good. On the contrary, if the tumor's radiographic boundary is not sclerotized, the tumor was thought to be a little more aggressive and the prognosis is not so good. Ameloblastomas with ill-defined boundary are thought to have the most aggressive behavior than others, which should be treated by the radical surgery because of the higher recurrent probability. With the ill-defined radiographic boundary, the tumor has the highest proliferative ability and poorest prognosis.
- Scholars believe that a radical surgery should be used for the multicystic ameloblastoma to prevent the recurrence. The follicular ameloblastomas were thought to have a higher recurrence rate than unicystic or plexiform. Scientists have found that ameloblastoma in children was mainly the plexiform type, and conservative treatment could be accepted as the initial treatment. Due to lack of the cortical plates, ameloblastoma in maxilla was thought to spread readily into the adjacent vital regions and suggested to be treated by extensive resection.[3]
Simple unicystic lesions are less common but have a better prognosis. Simple (no nodule) variant will not be diagnosable on radiography, as it will be indistinguishable form other more common cysts. Luminal variant, has a single nodule projecting into the cyst. Mural variant has multiple nodules (often only microscopic) in the wall of the cyst. The latter has an elevated risk of recurrence. Proliferation is a key feature of the progression of tumors. It was found that the proliferating activity of each type of ameloblastoma can be indexed by the expression of Ki-67 antigen.7,17,18 We found that the Ki-67 LI of the ameloblastoma in group III was the highest among the three groups which could be attributed to the fact that ameloblastoma with ill-defined radiographic boundary contained more cells with higher proliferative ability. This result was consistent with the retrospective analysis of clinical data. With the ill-defined radiographic boundary, the tumor has the highest proliferative ability and poorest prognosis.
References
- ↑ Gümgüm S, Hoşgören B (2005). "Clinical and radiologic behaviour of ameloblastoma in 4 cases". J Can Dent Assoc. 71 (7): 481–4. PMID 16026635.
- ↑ Morgan, Peter R. (2011). "Odontogenic tumors: a review". Periodontology 2000. 57 (1): 160–76. doi:10.1111/j.1600-0757.2011.00393.x. ISSN 0906-6713.
- ↑ Li, Yi; Han, Bo; Li, Long-Jiang (2012). "Prognostic and proliferative evaluation of ameloblastoma based on radiographic boundary". International Journal of Oral Science. 4 (1): 30–33. doi:10.1038/ijos.2012.8. ISSN 1674-2818.