Ameloblastoma natural history, complications and prognosis: Difference between revisions
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=== Natural History === | === Natural History === | ||
* In several cases the patients with [[ameloblastoma]] are asymptomatic, presenting as an incidental finding on orthopantomography. The most common symptoms are facial swelling, pain, malocclusion, loosening of teeth, ill-fitting dentures, periodontal diseases or ulceration, oroantral fistulas and nasal airway obstruction Additionally, because abnormal cell growth easily infiltrates and destroys surrounding bony tissues, wide surgical excision is required to treat this disorder. If an aggressive tumor is left untreated, it can obstruct the nasal and oral airways making it impossible to breathe without oropharyngeal intervention. If an aggressive tumor is left untreated, it can obstruct the nasal and oral airways making it impossible to breathe without oropharyngeal intervention. | |||
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Additionally, because abnormal cell growth easily infiltrates and destroys surrounding bony tissues, wide surgical excision is required to treat this disorder. If an aggressive tumor is left untreated, it can obstruct the nasal and oral airways making it impossible to breathe without oropharyngeal intervention. If an aggressive tumor is left untreated, it can obstruct the nasal and oral airways making it impossible to breathe without oropharyngeal intervention. | |||
Ameloblastoma is a true neoplasm of enamel organ type. Robinson described it as unicentric, nonfunctional, intermittent in growth, anatomically benign, and clinically persistent. It is the second most common odontogenic neoplasm. Histologically it is of six subtypes: follicular, plexiform, acanthomatous, granular, desmoplastic, and basilar. It affects mandible more than maxilla especially in the region of molar-ramus area. It causes a slow growing, painless expansion of jaw which causes thinning of cortical plates. Root resorption, tooth mobility, and paresthesia are features seen in advanced cases of ameloblastoma. Radiographically it can be unicystic, multicystic, or solid and peripheral type. Multicystic or solid type is prevalent in 86% of cases. Unicystic ameloblastoma is of three subtypes: luminal, intraluminal, and mural | Ameloblastoma is a true neoplasm of enamel organ type. Robinson described it as unicentric, nonfunctional, intermittent in growth, anatomically benign, and clinically persistent. It is the second most common odontogenic neoplasm. Histologically it is of six subtypes: follicular, plexiform, acanthomatous, granular, desmoplastic, and basilar. It affects mandible more than maxilla especially in the region of molar-ramus area. It causes a slow growing, painless expansion of jaw which causes thinning of cortical plates. Root resorption, tooth mobility, and paresthesia are features seen in advanced cases of ameloblastoma. Radiographically it can be unicystic, multicystic, or solid and peripheral type. Multicystic or solid type is prevalent in 86% of cases. Unicystic ameloblastoma is of three subtypes: luminal, intraluminal, and mural | ||
Ameloblastoma is a rare odontogenic epithelial tumor that represents only approximately 1 % of all jaw tumors, but it is the second-most common odontogenic tumor. Although it is always considered a benign odontogenic tumor, ameloblastoma is slow growing, locally aggressive, and has a high propensity for local recurrence if not removed completely. Some authors tend to regard it as a potentially malignant tumor [1], [2], but metastasis is rare. However, a histologically benign-appearing ameloblastoma can metastasize to local lymph nodes or other distant organs, such as the brain, lung, skin, etc. Over a decade can pass before metastatic tumors are observed after the resection of the primary tumor [3], [4]. Histologic appearance alone cannot indicate late metastasis. | Ameloblastoma is a rare odontogenic epithelial tumor that represents only approximately 1 % of all jaw tumors, but it is the second-most common odontogenic tumor. Although it is always considered a benign odontogenic tumor, ameloblastoma is slow growing, locally aggressive, and has a high propensity for local recurrence if not removed completely. Some authors tend to regard it as a potentially malignant tumor [1], [2], but metastasis is rare. However, a histologically benign-appearing ameloblastoma can metastasize to local lymph nodes or other distant organs, such as the brain, lung, skin, etc. Over a decade can pass before metastatic tumors are observed after the resection of the primary tumor [3], [4]. Histologic appearance alone cannot indicate late metastasis. | ||
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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, presenting as an incidental finding on orthopantomography. The most common symptoms are facial swelling, pain, malocclusion, loosening of teeth, ill-fitting dentures, periodontal diseases or ulceration, oroantral fistulas and nasal airway obstruction Additionally, because abnormal cell growth easily infiltrates and destroys surrounding bony tissues, wide surgical excision is required to treat this disorder. If an aggressive tumor is left untreated, it can obstruct the nasal and oral airways making it impossible to breathe without oropharyngeal intervention. If an aggressive tumor is left untreated, it can obstruct the nasal and oral airways making it impossible to breathe without oropharyngeal intervention.
Ameloblastoma is a true neoplasm of enamel organ type. Robinson described it as unicentric, nonfunctional, intermittent in growth, anatomically benign, and clinically persistent. It is the second most common odontogenic neoplasm. Histologically it is of six subtypes: follicular, plexiform, acanthomatous, granular, desmoplastic, and basilar. It affects mandible more than maxilla especially in the region of molar-ramus area. It causes a slow growing, painless expansion of jaw which causes thinning of cortical plates. Root resorption, tooth mobility, and paresthesia are features seen in advanced cases of ameloblastoma. Radiographically it can be unicystic, multicystic, or solid and peripheral type. Multicystic or solid type is prevalent in 86% of cases. Unicystic ameloblastoma is of three subtypes: luminal, intraluminal, and mural Ameloblastoma is a rare odontogenic epithelial tumor that represents only approximately 1 % of all jaw tumors, but it is the second-most common odontogenic tumor. Although it is always considered a benign odontogenic tumor, ameloblastoma is slow growing, locally aggressive, and has a high propensity for local recurrence if not removed completely. Some authors tend to regard it as a potentially malignant tumor [1], [2], but metastasis is rare. However, a histologically benign-appearing ameloblastoma can metastasize to local lymph nodes or other distant organs, such as the brain, lung, skin, etc. Over a decade can pass before metastatic tumors are observed after the resection of the primary tumor [3], [4]. Histologic appearance alone cannot indicate late metastasis.
- The majority of ameloblastomas expand slowly, they do so by infiltrating into the adjacent bone marrow and, if allowed to grow until there is extensive jaw expansion, they may penetrate the cortex and extend into muscle and other local soft tissues. The resulting tumors or cysts are usually benign but the tissue growth may be aggressive in the involved area. On rare occasions, tissue near the jaws, such as around the sinuses and eye sockets, may become involved as well. The tissues involved are most often those that give rise to the teeth so that ameloblastoma may cause facial distortion. Malignancy is uncommon as are metastases, but they do occur. Ameloblastoma is characterized by an abnormal growth in the jaw or sinus area, often at the site of the third molar. The tumors or cysts may be aggressive and may spread to the eye socket, nose, and skull.
- Although ameloblastoma is considered a benign odontogenic tumor, it is locally aggressive, slow growing, and has a high propensity for local recurrence if not removed completely.
- It is important for ameloblastoma to be diagnosed and treated early in order to stop growth of the tumors and possible progression to cancer. Although it is uncommon, ameloblastomas have been known to become malignant and spread to other parts of the body, especially to the lungs.
- Ameloblastomas have a significant recurrence rate traditionally ranging between 5% and 30% over periods ranging from 5 to 15 years, thus necessitating resection. The initial surgical treatment must be carefully and scrupulously done to avoid recurrence. Ameloblastomas do not usually become malignant. Evidence suggests that ameloblastoma is more likely to become malignant if the condition reoccurs after surgery.The initial surgical treatment must be carefully and scrupulously done to avoid recurrence.
- Clinically, ameloblastoma appears as an aggressive odontogenic tumour, often asymptomatic and slow growing, with no evidence of swelling. It can sometimes cause
symptoms such as dental malocclusion, swelling, pain and paresthesia of the affected area. It spreads by forming pseudopods in marrow spaces without concomitant resorption of the trabecular bone. As a result, the margins of the tumour are not clearly seen on radiographs or during surgery and the tumour frequently recurs after inadequate surgical removal. The appearance of septae on the radiograph usually represents differential resorption of the cortical plate by the tumour and not actual separation of tumour portions. Because of its slow growth, recurrences of ameloblastoma generally present many years and even decades after primary surgery.6 When treated inadequately, malignant development is a possibility.[1][2]
Complications
According to World Health Organization (WHO) ameloblastoma is a benign tumor. Metastases to the lungs or central nervous system (CNS) have rarely been reported. 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%. The tumor can recur after treatment and hence, a close follow-up is needed.
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.