Ameloblastic fibro-odontoma

The ameloblastic fibro-odontoma (AFO) is essentially a benign tumor with the features characteristic of ameloblastic fibroma along with enamel and dentin (hard tissues).[1] Though it is generally regarded as benign, there have been cases of its malignant transformation into ameloblastic fibrosarcoma [2] and odontogenic sarcoma.[3] Cahn LR and Blum T, believed in “maturation theory”, which suggested that AFO was an intermediate stage and eventually developed during the period of tooth formation to a complex odontoma thus, being a hamartoma.[4]

World Health Organization (WHO) defines AFO as a neoplasm consisting of odontogenic ectomesenchyme resembling the dental papilla, epithelial strands and nest resembling dental lamina and enamel organ conjunction with the presence of dentine and enamel. There is a consensus that AFO should be grouped under Odontomas. This is because once the hard tissues start forming it will eventually lead to formation of Odontomas.[5] The Recent WHO classification published in 2017

has grouped AFDs into odontomes.[6][7] According to Tekkesin S et al, combination of age and lesion size should be used to distinguish between lesions of a true neoplastic nature and hamartomatous formation.[8]

History

Initially, AFO was called as ameloblastic odontoma. Hooker in 1967 first used the term ameloblastic fibro-odontoma.[9] WHO classified odontogenic tumors for the first time in 1971 (1stedition).[10][11] In 2005, mixed tumors were included in the classification of odontogenic tumors by WHO as tumors having odontogenic epithelium along with odontogenic ectomesenchyme.[12] This includes ameloblastic fibroma (AF), ameloblastic fibro-dentinoma (AFD), ameloblastic fibro-odontoma (AFO) and odontoma amongst others. According to the continuum concept, AF, AFD, AFO and odontoma lie in the same spectrum but at different sides depending upon the maturation with AF and odontoma lying completely opposite whereas AFD and AFO lying between them. AFO consists of odontogenic epithelium along with enamel and dentin. Such inductive changes along with proliferating odontogenic epithelium warrant AFO to be regarded as a separate entity.

Key Highlights for Differentiation (Histologically)
Lesion Components Histological Difference
AF Neoplastic epithelium + Ectomesenchyme
AFD Neoplastic epithelium + Ectomesenchyme + Dentin
AFO Neoplastic epithelium + Ectomesenchyme + Enamel + Dentin
Odontome Neoplastic epithelium (non-proliferating) + Ectomesenchyme + {Enamel + Dentin in unorganized fashion}

Histogenesis

AFO is regarded as a benign mixed odontogenic tumor. Cahn and Blum first advocated continuum concept but this was later rejected. AFO is now considered as a distinct entity.[4] AFO exhibits the same benign biologic behavior as that of AF, along with inductive changes that lead to the formation of both dentin and enamel.[13]

Prevalence

AFO is a rare odontogenic tumor and accounts for around 2% of all the jaw tumors.[14][15][16] This neoplasm usually occurs in the first and second decade of life and is most common in the posterior region of mandible.[17] There appears no gender predilection.[17] Slootweg PJ established that the data on age, site, and sex were consistent with the concept that the AFO was an immature complex odontoma,[18] thereby indicating that AFO was a hamartoma.[16]

Clinical presentation

AFO is seen in younger age groups, commonly in the second decade of life.[17] Failure and failure of tooth eruption are the most common presenting complaints. In case of large swellings, it may show deformity and show displacement of erupted teeth. Pain and paresthesia are not features of AFO. Accidental discovery during radiographical investigation may be possible.[19] The lesion occurs most commonly in the posterior region of the jaw (mandible). Massive maxillary AFOs cause destruction of the sinus, facial disfigurement, perforated the cortical plates or extended to the orbital floor-pterygoid region.[20][21]

Radiographical features

AFO is essentially a radiolucent lesion that is generally unilocular and rarely multilocular. The radiolucency contains calcified material depicting as radio-opaque areas of variable size. The amount of calcified material present is variable and hence the lesion may be either radiolucent, radio-opaque or mixed. Associated crown of the unerupted tooth may be evident.[22]

Histopathology

The cell-rich mesenchymal tissue resembles the primitive dental papilla. The odontogenic epithelium may be either arranged as follicles that resemble developing enamel organ or they may be seen as cords or strands. The peripheral cells of the follicles resemble ameloblast like cells The odontogenic epithelium is scattered in a loose connective tissue stroma that closely resembles dental papilla. Calcified material may resemble enamel or dentin matrix. The mature lesions may show enamel or dentin aggregates.[17]

See also

References
  1. Surej Kumar LK, Manuel S, Khalam SA, Venugopal K, Sivakumar TT, Issac J (2014). "Ameloblastic fibro-odontoma". International Journal of Surgery Case Reports. 5 (12): 1142–1144. doi:10.1016/j.ijscr.2014.11.025. PMC 4276268. PMID 25437658.
  2. Howell RM, Burkes EJ (March 1977). "Malignant transformation of ameloblastic fibro-odontoma to ameloblastic fibrosarcoma". Oral Surgery, Oral Medicine, and Oral Pathology. 43 (3): 391–401. doi:10.1016/0030-4220(77)90326-7. PMID 265043.
  3. Herzog U, Putzke HP, Bienengräber V, Radke C (March 1991). "[The ameloblastic fibro-odontoma--an odontogenic mixed tumor progressing into an odontogenic sarcoma]". Deutsche Zeitschrift für Mund-, Kiefer- und Gesichts-Chirurgie. 15 (2): 90–93. PMID 1816940.
  4. Trachoo V, Vipismakul V (2019). "Ameloblastic Fibro-odontoma or Immature Odontoma: A Retrospective Analysis of 134 Cases". Journal of Clinical and Diagnostic Research. doi:10.7860/jcdr/2019/42144.13154. ISSN 2249-782X. S2CID 204060859.
  5. Wright JM, Vered M (March 2017). "Update from the 4th Edition of the World Health Organization Classification of Head and Neck Tumours: Odontogenic and Maxillofacial Bone Tumors". Head and Neck Pathology. 11 (1): 68–77. doi:10.1007/s12105-017-0794-1. PMC 5340735. PMID 28247226.
  6. Speight PM, Takata T (March 2018). "New tumour entities in the 4th edition of the World Health Organization Classification of Head and Neck tumours: odontogenic and maxillofacial bone tumours". Virchows Archiv. 472 (3): 331–339. doi:10.1007/s00428-017-2182-3. PMC 5886999. PMID 28674741.
  7. Westra WH, Lewis JS (March 2017). "Update from the 4th Edition of the World Health Organization Classification of Head and Neck Tumours: Oropharynx". Head and Neck Pathology. 11 (1): 41–47. doi:10.1007/s12105-017-0793-2. PMC 5340734. PMID 28247229.
  8. Soluk-Tekkesin M, Vered M (December 2021). "Ameloblastic Fibro-Odontoma: At the Crossroad Between "Developing Odontoma" and True Odontogenic Tumour". Head and Neck Pathology. 15 (4): 1202–1211. doi:10.1007/s12105-021-01332-6. PMC 8633217. PMID 33991318.
  9. Hooker SP (September 1967). "Ameloblastic odontoma: An analysis of twenty-six cases". Oral Surgery, Oral Medicine, Oral Pathology. 24 (3): 375–376. doi:10.1016/0030-4220(67)90054-0. ISSN 0030-4220.
  10. Kramer IR, Pindborg JJ, Shear M (1992). "Histological Classification of Odontogenic Tumours". Histological Typing of Odontogenic Tumours. Berlin, Heidelberg: Springer Berlin Heidelberg. pp. 7–9. doi:10.1007/978-3-662-02858-2_2. ISBN 978-3-540-54142-4.
  11. Pindborg JJ (1971). Histological typing of odontogenic tumours, jaw cysts and allied lesions. WHO. OCLC 1230918238.
  12. Philipsen HP, Reichart PA (May 2002). "Revision of the 1992-edition of the WHO histological typing of odontogenic tumours. A suggestion". Journal of Oral Pathology & Medicine. 31 (5): 253–258. doi:10.1034/j.1600-0714.2002.310501.x. PMID 12110040.
  13. de Souza Tolentino E, Centurion BS, Lima MC, Freitas-Faria P, Consolaro A, Sant'ana E (2010). "Ameloblastic fibro-odontoma: a diagnostic challenge". International Journal of Dentistry. 2010: 1–4. doi:10.1155/2010/104630. PMC 2933904. PMID 20827417.
  14. Gantala R, Gotoor SG, Kumar RV, Munisekhar MS (June 2015). "Ameloblastic fibro-odontoma". BMJ Case Reports. 2015 (jun04 1): bcr2015209739. doi:10.1136/bcr-2015-209739. PMC 4460434. PMID 26045519.
  15. Nelson BL, Thompson LD (June 2014). "Ameloblastic fibro-odontoma". Head and Neck Pathology. 8 (2): 168–170. doi:10.1007/s12105-013-0501-9. PMC 4022943. PMID 24197722.
  16. Slootweg PJ (March 1981). "An analysis of the interrelationship of the mixed odontogenic tumors--ameloblastic fibroma, ameloblastic fibro-odontoma, and the odontomas". Oral Surgery, Oral Medicine, and Oral Pathology. 51 (3): 266–276. doi:10.1016/0030-4220(81)90056-6. PMID 6938886.
  17. Neville BW, Damm DD, Allen CM, Bouquot JE (2009). Oral and Maxillofacial Pathology (3rd ed.). St. Louis, Mo.: Saunders/Elsevier. doi:10.1016/b978-1-4160-3435-3.50002-6. ISBN 978-1-4160-3435-3.
  18. Barba LT, Campos DM, Rascón MM, Barrera VA, Rascón AN (October 2016). "Descriptive aspects of odontoma: literature review". Revista Odontológica Mexicana. 20 (4): e265-9. doi:10.1016/j.rodmex.2016.11.018.
  19. Chang H, Precious DS, Shimizu MS (April 2002). "Ameloblastic fibro-odontoma: a case report". Journal. 68 (4): 243–246. PMID 12626279.
  20. Piette EM, Tideman H, Wu PC (May 1990). "Massive maxillary ameloblastic fibro-odontoma: case report with surgical management". Journal of Oral and Maxillofacial Surgery. 48 (5): 526–530. doi:10.1016/0278-2391(90)90247-y. PMID 2329404.
  21. Hegde V, Hemavathy S (2008). "A massive ameloblastic fibro-odontoma of the maxilla". Indian Journal of Dental Research. 19 (2): 162–164. doi:10.4103/0970-9290.40474. PMID 18445937.
  22. Buchner A, Kaffe I, Vered M (March 2013). "Clinical and radiological profile of ameloblastic fibro-odontoma: an update on an uncommon odontogenic tumor based on a critical analysis of 114 cases". Head and Neck Pathology. 7 (1): 54–63. doi:10.1007/s12105-012-0397-9. PMC 3597150. PMID 23001451.
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