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User:InsufficientData/Sandbox/Ameloblastoma

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InsufficientData/Sandbox/Ameloblastoma

Ameloblastoma 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. It was recognized in 1827 by Cusack.[1] This type of odontogenic neoplasm was designated as an adamantinoma in 1885 by Malassez[2] and was finally renamed to the modern name ameloblastoma in 1930 by Ivey and Churchill.[3][4]

While these tumors are rarely malignant or metastatic (that is, they rarely spread to other parts of the body), and progress slowly, the resulting lesions can cause severe abnormalities of the face and jaw. Additionally, because abnormal cell growth easily infiltrates and destroys surrounding bony tissues, wide surgical excision is required to treat this disorder. Further, dentists caution that wide surgical excision is not invasive enough to adequately treat this disorder.

Subtypes

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There are three main clinical subtypes of ameloblastoma: unicystic, multicystic, peripheral. A fourth subtype, malignant, has been considered by some oncologic specialists, however, this form of the tumor is rare and may be simply a manifestation of one of the three main subtypes..

Clinical features

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Ameloblastomas are often associated with the presence of unerupted teeth. Symptoms include painless swelling, facial deformity if severe enough, pain if the swelling impinges on other structures, loose teeth, ulcers, and periodontal (gum) disease. Lesions will occur in the mandible and maxilla,although 75% occur in the ascending ramus area and will result in extensive and grotesque deformitites of the mandible and maxilla. In the maxilla it can extend into the maxillary sinus and floor of the nose. The lesion has a tendency to expand the bony cortices because slow growth rate of the lesion allows time for periosteum to develop thin shell of bone ahead of the expanding lesion. This shell of bone cracks when palpated and this phenomenon is referred to as "Egg Shell Cracking" or crepitus, an important diagnostic feature. Ameloblastoma is tentatively diagnosed through radiographic examination and must be confirmed by histological examination (e.g., biopsy). Radiographically, it appears as a lucency in the bone of varying size and features--sometimes it is a single, well-demarcated lesion whereas it often demonstrates as a multiloculated "soap bubble" appearance. Resorption of roots of involved teeth can be seen in some cases, but is not unique to ameloblastoma. The disease is most often found in the posterior body and angle of the mandible, but can occur anywhere in either the maxilla or mandible.

Ameloblastoma is often associated with bony-impacted wisdom teeth--one of the many reasons dentists recommend having them extracted.

Histopathology

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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". 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. 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.

Variants

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The six different histopathological variants of ameloblastoma are desmoplastic, granular cell, basal cell, plexiform, follicular, and acanthomatous.[5]

The acanthomatous variant is extremely rare.[6]

Treatment

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Ameloblastomas are relatively resistant to chemotherapy or radiation therapy, thus, surgery is the most common treatment of this tumor. Because of the invasive nature of the growth, excision of normal tissue near the tumor margin is often required. Some have likened the disease to basal cell carcinoma (a skin cancer) in its tendency to spread to adjacent bony and sometimes soft tissues without metastasizing. 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

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Recurrence is common and persistent follow-up examination is essential for managing ameloblastoma.[7]

Treatment with radiation

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There are mixed reports about treating ameloblastomas with radiation.

Much of consensus is that radiation isn't effective or shouldn't be used the primary treatment for ameloblastomas.[8] There have also been reports of sarcomas being induced as the result of using radiation to treat ameloblastomas.[9] Chemotherapy isn't a successful treatment.[9]

However, there is some controversy regarding this[10] and some indication that some ameloblastomas might be more responsive to radiation that previously thought.[11][4]

While the Mayo Clinic recommends surgery for almost all ameloblastomas, there are situations in which a Mayo Clinic physician might recommend radiation therapy. According to their website[12], these include:

  • malignancy
  • inability to completely remove the ameloblastoma
  • recurrence
  • unacceptable loss of function
  • unacceptable cosmetic damage.

In the case of radiotherapy, oncologists at the Mayo Clinic would use intensity-modulated radiotherapy.[12]

Molecular biology

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There is evidence that suppression of matrix metalloproteinase-2 may inhibit the local invasiveness of ameloblastoma, however, this was only demonstrated in vitro.[13]

Epidemiology

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The annual incidence rates per million for ameloblastomas are 1.96, 1.20, 0.18 and 0.44 for black males, black females, white males and white females respectively[14]. Ameloblastomas account for about one percent of all oral tumors[15] and about 18% of odontogenic tumors.[16]

See also

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References

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  1. ^ J.W. Cusack (1827). "Report of the amputations of the lower jaw". Dublin Hosp Rec. 4: 1–38.
  2. ^ L. Malassez (1885). "Sur Le role des debris epitheliaux papdentaires". Arch Physiol Norm Pathol. 5: 309–340 6:379–449.
  3. ^ R.H. Ivey, H.R. Churchill (1930). "The need of a standardized surgical and pathological classification of tumors and anomalies of dental origin". Am Assoc Dent Sch Trans. 7: 240–245.
  4. ^ a b Madhup, Rastogi; Kirti, Srivastava; Bhatt, M.L.B.; Srivastava, M.; Sudhir, Singh; Srivastava, A.N. (Jan 2006). "Giant ameloblastoma of jaw successfully treated by radiotherapy". Oral Oncology Extra. 42 (1): 22–25. doi:10.1016/j.ooe.2005.08.004.{{cite journal}}: CS1 maint: date and year (link)
  5. ^ Gruica B, Stauffer E, Buser D, Bornstein M. (Apr 2003). "Ameloblastoma of the follicular, plexiform, and acanthomatous type in the maxillary sinus: a case report". Quintessence Int. 34 (4): 311–4. PMID 12731620.{{cite journal}}: CS1 maint: date and year (link) CS1 maint: multiple names: authors list (link)
  6. ^ Vaishali A. Walke (April 2008). "Cytological diagnosis of acanthmatous ameloblastoma". Journal of Cytology. 25 (2).{{cite journal}}: CS1 maint: date and year (link)
  7. ^ Martins WD; Fávaro DM. (Dec 2004). "Recurrence of an ameloblastoma in an autogenous iliac bone graft". Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 98 (6): 657–659. doi:10.1016/j.tripleo.2004.04.020. PMID 15583536.{{cite journal}}: CS1 maint: date and year (link) CS1 maint: multiple names: authors list (link)
  8. ^ Yan Trokel, BA; Robert Himmelfarb, DDS; William Schneider, MD, DDS; Robert Hou, MD DDS (3 JAN 2009). "An Update on the Management of a Recurrent Ameloblastoma: A Case Report and Review of Literature". {{cite web}}: Check date values in: |date= (help)CS1 maint: multiple names: authors list (link)
  9. ^ a b Randall S. Zane, M.D. (3 JAN 2009). "Maxillary Ameloblastoma". {{cite web}}: Check date values in: |date= (help); Unknown parameter |createdate= ignored (help)
  10. ^ Atkinson CH, Harwood AR, Cummings BJ. (15 February 1984). "Ameloblastoma of the jaw. A reappraisal of the role of megavoltage irradiation". Cancer. 53 (4): 869–73. doi:10.1002/1097-0142(19840215)53:4<869::AID-CNCR2820530409>3.0.CO;2-V. PMID 6420036. S2CID 72371028.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  11. ^ Miyamoto CT, Brady LW, Markoe A, Salinger D (June 1991). "Ameloblastoma of the jaw. Treatment with radiation therapy and a case report". Am J Clin Oncol. 14 (3): 225–30. doi:10.1097/00000421-199106000-00009. PMID 2031509. S2CID 33468547.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  12. ^ a b "Ameloblastoma Treatment". Mayo Clinic. 3 JAN 2009. {{cite web}}: Check date values in: |date= (help)
  13. ^ Anxun Wang, Bin Zhang, Hongzhang Huang, Leitao Zhang, Donglin Zeng, Qian Tao, Jianguang Wang and Chaobin Pan (2008). "Suppression of local invasion of ameloblastoma by inhibition of matrix metalloproteinase-2 in vitro". BMC Cancer. 8 (182): 182. doi:10.1186/1471-2407-8-182. PMC 2443806. PMID 18588710.{{cite journal}}: CS1 maint: multiple names: authors list (link) CS1 maint: unflagged free DOI (link)
  14. ^ Shear, M.; Singh, S. (July 1978). "Age-standardized incidence rates of ameloblastoma and dentigerous cyst on the Witwatersrand, South Africa". Community Dent Oral Epidemiology. 6 (4): 195–199. doi:10.1111/j.1600-0528.1978.tb01149.x. PMID 278703.{{cite journal}}: CS1 maint: date and year (link)
  15. ^ Randall S. Zane, M.D. (10 August 1991). "Maxillary Ameloblastoma". Retrieved 16 December 2008.
  16. ^ Jonathan Gordon, M.D., Ph.D. (30 DEC 2008). "Clinical Quiz: Painless Mass". Appl Radiol Online. 3 (8). {{cite journal}}: Check date values in: |date= and |year= / |date= mismatch (help)CS1 maint: multiple names: authors list (link)
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