Oral Med Pathol 7 (2002) 55

Ameloblastic Fibroma: A critical evaluation of reported cases provides evidence of two types

Fumio Ide 1, Munenori Kitada 2, Akio Tanaka 2, Hideaki Sakashita 2 and Kaoru Kusama 1 1 Department of Oral Pathology, 2 Second Department of Oral and Maxillofacial Surgery, Meikai University School of Dentistry, Sakado, Japan

Ide F, Kitada M, Tanaka A, Sakashita H and Kusama K. Ameloblastic fibroma: A critical evaluation of reported cases provides evidence of two types. Oral Med Pathol 2002; 7: 55-59, ISSN 1342-0984

There is still controversy as to the clinical findings and behavior of ameloblastic fibroma (AF). To clarify the exact biological profile, we critically re-evaluated the clinical characteristics of 31 cases of AF through a review of the Japanese literature. AF can be divided clinically into two distinct types: neoplastic AF (24 cases) and pericoronal hamartomatous AF (7 cases). The former appears as an expansive multilocular radiolucent lesion within the posterior mandible in the second decade. A recurrence rate of 13% was estimated. Its tendency to recur and to develop at ages beyond completion of odontogenesis clearly denotes a neoplastic nature. On the other hand, the latter appears as an asymptomatic small unilocular radiolucency over the occlusal surface of an unerupted mandibular molar primarily in the first decade. Neither persistent growth nor recurrence was observed. There is no proof that pericoronal AF sequentially progresses into a neoplastic AF. However, since two lesions are histologically indistinguishable, clinical findings have to be considered initially in a management plan of AF.

Key words:ameloblastic fibroma, biological profile, odontogenic hamartoma, , pericoronal lesion Correspondence: Fumio Ide, Department of Oral Pathology, Meikai University School of Dentistry, 1-1 Keyakidai, Sakado, Saitama 350-0283, Japan Phone: +81-492-79-2773, Fax: +81-492-86-6101

Introduction sive and non-recurrent nature. In addition, the histopatho- Ameloblastic fibroma (AF) is the prototype or the logic diversity, the other remaining gap in our knowledge least histologically differentiated of so-called mixed od- of AF, will be discussed briefly. ontogenic tumors (1-6). Although more than 150 cases, including Japanese reports, have been published (4), con- Review of the Literature flicting data exist in the literature on the clinical charac- Through a review of the Japanese literature, we teristics. For example, some were found incidentally by retrieved 31 well-documented cases of AF with each microscopic examination of the dental follicular tissue of patient’s clinical record and photomicrographs (25-54). unerupted teeth (7-9), whereas others appeared as a large All papers published in abstract form or without adequate expanding lesion suggestive of neoplasm (10-23). Most photographs were deemed unacceptable (55). We also ex- authors consider that AF rarely ever recurs (1-6), but cluded a possible recurrent case, since the histological Trodahl (24) recorded a 43% cumulative recurrence rate. diagnosis of the primary tumor was uncertain (56). It is still, at present, a matter of debate whether AF is a truly neoplastic entity or a developmental anomaly True neoplastic AF (25-47) (hamartoma). The median age of the 24 patients was 14 years In this context, we attempt to clarify the biological (range, 1-38); 11 patients were diagnosed in the second profile of AF based on a literature survey. There can be decade. One lesion was observed at birth (26). The tumor no doubt that two different clinical types that have the was equally encountered in both genders. Nineteen tu- same histologic features exist. It is clinically important mors (79%) occurred in the mandible and 13 in the poste- to realize the entity of pericoronal AF has a non-aggres- rior segment. None developed in the anterior maxilla. 56 Ide et al. Ameloblastic fibroma

Painless swelling was the first symptom in 21 cases (88%). though inconclusive. All patients were asymptomatic and Radiographically, 15 cases (71%) were associated with an failure of tooth eruption was the major reason for seek- impacted tooth and 12 (60%) showed a multilocular radi- ing treatment. Five lesions (71%) were associated with a olucency. Three cases (13%) recurred at 3, 4 and 12 years deciduous tooth and 2 with a permanent tooth. The ra- after first operation, respectively (27, 45, 46). One patient diographic finding in 4 cases (80%) was a unilocular ra- was of particular interest since the tumor recurred twice diolucency. No recurrence was observed. The dental folli- (45). Another 13 cases of recurrent AF have been reported cular origin of pericoronal AF is apparent. The compari- (24, 57-61). Although there are no specific clinicopatho- son of clinical findings between true neoplastic and peri- logical findings to predict the recurrence, the mean time coronal hamartomatous AF is summarized in Table 1. between initial treatment and recurrence was 4 years, ranging from 6 months (24) to 23 years (60). Therefore, Discussion careful follow-up of more than 4 years is mandatory. The So-called mixed odontogenic tumors have been a higher frequency of association with the impacted tooth topic of academic interest to oral pathologists. One of suggests that AF may have arisen from cells in the den- major interests that has been investigated is whether tal follicle. these tumors represent different stages in the histomorphological differentiation of the same entity (1- Pericoronal hamartomatous AF (48-54) 6). With regard to AF, it is generally agreed that some The age of the 7 patients ranged from 1 to 11 years, cases are true neoplasms, whereas others are hamarto- with a median of 5 years. One lesion was found at birth mas presenting the earliest stage in the developing od- (53). Four patients were female and 3 male. Six cases ontoma (1-6). In this review, our critical evaluation of re- (86%) occurred in the mandible, especially in the poste- ported cases provided evidence of two clinical types: a true rior segment. Only one case developed in the anterior neoplastic AF and a pericoronal hamartomatous AF. How- maxilla (54). Interestingly, two examples of peripheral AF ever, it is not possible to state with certainty that peri- were recorded (48, 53) ; however, it is our impression that coronal AF may maturate over time, eventually leading they are not a true peripheral lesion but rather an erupted to the formation of an , unless such evidence is pericoronal AF occurring during tooth development, al- forthcoming.

Table 1: True neoplastic and pericoronal hamartomatous ameloblastic fibromas Oral Med Pathol 7 (2002) 57

The concept of pericoronal AF has already been References discussed in the literature (2, 7-9) ; however, its existence 1. Slootweg PJ. An analysis of the interrelationship of the mixed as a separate entity is not widely accepted. As mentioned odontogenic tumors-ameloblastic fibroma, ameloblastic fibro- above, this lesion develops during childhood (the period odontoma, and the . Oral Surg 1981; 51: 266-76. of normal odontogenesis) and has little or no prolifera- 2. Gardner DG. The mixed odontogenic tumors. Oral Surg 1984; tive potential. It does not recur. Indeed, in all cases leav- 58: 166-8. ing the underlying tooth in toto, the involved tooth was 3. Hansen LS and Ficarra G. Mixed odontogenic tumors: an permitted to erupt, even when the lesion extended to the analysis of 23 new cases. Head Neck Surg 1988; 10: 330-43. surgical margins. Similar clinical findings and behavior 4. Philipsen HP, Reichart PA and Praetorius F. Mixed odonto- have also been documented in non-Japanese cases (2-4, genic tumours and odontomas. Considerations on interrela- 6, 62-73). Such characteristics would favor the interpre- tionship. Review of the literature and presentation of 134 tation of a hamartomatous nature. Therefore, oral sur- new cases of odontomas. Oral Oncol 1997; 33: 86-99. geons must realize the non-neoplastic character of 5. Takeda Y. Ameloblastic fibroma and related lesions: current pericolonal AF and it should be treated pathologic concept. Oral Oncol 1999; 35: 535-40. ultraconservatively. 6. Tomich CE. Benign mixed odontogenic tumors. Semin Diagn The most important problem is that a histologic Pathol 1999; 16: 308-16. distinction between two types of AF is impossible. The 7. Philipsen HP, Thosaporn W, Reichart PA, et al. Odontogenic histopathology of AF is well-described and well-photo- lesions in opercula of permanent molars delayed in erup- graphed (74, 75) ; however, it shows a more considerable tion. J Oral Pathol Med 1992; 21: 38-41. histologic diversity than generally believed (76). The 8. Kim J and Ellis GL. Dental follicular tissue: misinterpreta- amount and morphology of both epithelial and tion as odontogenic tumors. J Oral Maxillofac Surg 1993; ectomesenchymal components vary from case to case and 51: 762-7. from area to area within the same tumor. Consequently, 9. Yonemochi H, Noda T and Saku T. Pericoronal hamartoma- some contain larger epithelial islands composed of a pe- tous lesions in the opercula of teeth delayed in eruption: an ripheral palisading of columnar ameloblastic cells and a immunohistochemical study of the extracellular matrix. J central stellate reticulum-lke area, whereas others con- Oral Pathol Med 1998; 27: 441-52. tain only smaller double-layered -like rests. 10. Snyder BS and Kolas S. Ameloblastofibroma of the mandible: The former shows the close resemblance to ameloblas- report of a case. J Oral Surg 1960; 18: 175-8. toma and the latter may mimic the odontogenic fibroma 11. Shira RB and Bhaskar SN. Oral surgery-oral pathology con- of the WHO or complex type. The ectomesenchymal com- ference no. 7. Oral Surg Oral Med Oral Pathol 1963; 16: 1377- ponent also varies, ranging from a cell-rich myxomatous 82. dental papilla-like or primitive pulp-like tissue to a 12. Grenfell JW and Maris AM. Ameloblastic fibroma. Report of hypocellular collagenous tissue. The latter may often be a case. Oral Surg Oral Med Oral Pathol 1966; 21: 403-6. misinterpreted as a desmoplastic . The 13. Olofsson J. Ameloblastic fibroma. Acta Otolaryngol 1972; 74: histopathology of AF and related lesions, including the 302-6. variability and diagnostic pitfalls, will be discussed in 14. Singh J, Singh B and Saigal RK. Ameloblastic fibroma. Case more detail in our next treatise (76). report. Aust Dent J 1975; 20: 281-2. 15. Shepherd N and Cataldo E. Ameloblastic fibroma: report of Summary case. J Oral Surg 1976; 34: 1022-5. The clinical characteristics of reported cases of AF 16. Hager RC, Taylor CG and Allen PM. Ameloblastic fibroma: are sufficiently different to recognize two separate lines. report of case. J Oral Surg 1978; 36: 66-9. These include a relatively innocuous benign tumor and a 17. Harrison WS, Sordill WC, Sciubba JJ, et al. Ameloblastic fi- pericoronal hamartoma. However, two lesions do not com- broma: management of a patient with an extensive tumor. J prise a continuum. Including a hamartomatous AF into a Am Dent Assoc 1982; 104: 475-7. true AF category results in the erroneous biological pro- 18. Girdler NM and Edwards DM. Ameloblastic fibroma-an un- file of a neoplastic AF. Unfortunately, we have no histo- usual case of facial swelling in a young child. Br Dent J 1990; logic method for differentiating the two. Conversely, we 169: 57-8. cannot predict the clinical behavior of AF on histologic 19. Carrillo R, Cuesta C, Rodriguez-Peralto JL, et al. Ameloblastic grounds. However, it is no longer acceptable to simply fibroma. Report of a case with fine needle aspiration cyto- refer to these lesions as AF. All oral pathologists should logic findings. Acta Cytol 1992; 36: 537-40. add an informative phrase in their report correlated to 20. Dellera P, Bertoni F, Marchetti C, et al. Ameloblastic fibroma: the clinical findings. a follow-up of six cases. Int J Oral Maxillofac Surg 1996; 25: 199-202. 21. Bocklage TJ, Ardeman T and Schaffner D. Ameloblastic fi- broma: a fine-needle aspiration case report. Diagn Cytopathol 1997; 17: 280-6. 58 Ide et al. Ameloblastic fibroma

22. Naidoo LCD and Stephen LXG. Congenital ameloblastic fi- 42. Sakaki T, Kaji R, Wato M, et al. A segmental ameloblastic broma in association with oculoauriculovertebral spectrum. fibroma in the maxilla. Jpn J Oral Maxillofac Surg 1993; Int J Pediatr Otorhinolaryngol 1998; 43: 283-8. 39: 481-3. 23. Mohapatra PK, Choudhury AR and Parkash H. Ameloblastic 43. Okabe K, Fujimoto E, Nakagawa K, et al. A case of fibroma in the midline of mandible: a case report. J Clin ameloblastic fibroma at the apical region of the left man- Pediatr Dent 2000; 24: 321-9. dibular molar. Jpn J Oral Maxillofac Surg 1995; 41: 248-50. 24. Trodahl JN. Ameloblastic fibroma. A survey of cases from 44. Sasakura Y, Kobori M, Ohmi Y, et al. A case of ameloblastic the Armed Forces Institute of Pathology. Oral Surg 1972; 33: fibroma. Jpn J Oral Diagn/Oral Med 1995; 8: 482-6. 547-58. 45. Shimizu Y, Yamada T, Sugitani M, et al. A case of ameloblastic 25. Suzuki K and Ikeda T. A case of soft fibroadamantinoma. J fibroma with repeated recurrences followed up for 18 years. Dent 1945; 2: 31-3. Nihon Univ J Med 1996; 38: 219-26. 26. Matsumoto Y, Inaba O and Yamamoto S. A case of 46. Sano K, Yoshida S, Ninomiya H, et al. Assessment of growth ameloblastic fibroma. J Jpn Stomatol Soc 1971; 20: 829-33. potential by MIB-1 immunohistochemistry in ameloblastic 27. Tanaka S, Mitsui Y, Mizuno Y, et al. Recurrent ameloblastic fibroma and related lesions of the jaws compared with fibroma. Report of a case. Oral Surg 1972; 33: 944-50. ameloblastic fibrosarcoma. J Oral Pathol Med 1998; 27: 59- 28. Mori M, Shimozato T, Kawano S, et al. Ameloblastic fibroma 63. and ameloblastic sarcoma. A report of the cases, histopathol- 47. Muraoka S, Yoshii T, Hamamoto Y, et al. A case of ameloblastic ogy and histochemistry. J Osaka Univ Dent Sch 1972; 12: fibroma in the mandible and clinicostatistical analysis of the 91-107. cases reported in Japan. Jpn J Oral Diagn/Oral Med 1999; 29. Arai S, Higa J and Sonoyama N. A case of ameloblastic fi- 12: 423-9. broma. Jpn J Oral Surg 1974; 20: 42-4. 48. Nakamura M and Tamai K. A case of ameloblastic fibroma 30. Seno Y, Nakagawa H, Ono S, et al. A case of ameloblastic in an infant (2-year-old). J Jpn Stomatol Soc 1980; 29: 99- fibroma occurring in the maxilla. J Jpn Stomatol Soc 1975; 103. 24: 359-62. 49. Katao H, Mine M, Daitou M, et al. A case of ameloblastic 31. Kurashina K, Takeda S, Morita T, et al. A case of ameloblastic fibroma. Jpn J Pedod 1982; 20: 534-9. fibroma occurring in the maxilla. J Jpn Stomatol Soc 1977; 50. Shimoyama I, Nishijima K, Nagahata S, et al. A case of 26: 496-500. ameloblastic fibroma. J Jpn Stomatol Soc 1982; 31: 430-7. 32. Inoue T, Shimono M, Ichikawa T, et al. A case of ameloblastic 51. Kurenuma S, Mori M, Isogai M, et al. A case report of fibroma. Light and electron microscopic observations. Jpn J ameloblastic fibroma. Radiographic observation for 3 years Oral Surg 1979; 25: 384-93. and 8 months. Jpn J Oral Maxillofac Surg 1983; 29: 1791-3. 33. Sakuda M, Yamamoto M, Shirasuna K, et al. Ameloblastic 52. Kakizawa T, Sekikawa Y, Hayashi H, et al. A case of fibroma of the maxilla; Report of a case. J Osaka Univ Dent ameloblastic fibroma. Jpn J Oral Maxillofac Surg 1986; 32: Sch 1979; 19: 119-28. 867-72. 34. Hibino Y, Mashiko K, Yoshida M, et al. Ameloblastic fibroma 53. Harada H, Kusukawa J, Oh-uchida M, et al. Ameloblastic of the median mandible: report of a case. Jpn J Oral Surg fibroma in an infant. A case report. J Jpn Soc Oral Tumors 1982; 28: 286-90. 1992; 4: 286-93. 35. Segami N, Hosoda M, Fukuda M, et al. A case of ameloblastic 54. Shintani S, Yoshihama Y, Ootsuki K, et al. A case of fibroma and its review of the literature. Jpn J Oral Maxillofac ameloblastic fibroma in child. Jpn J Oral Maxillofac Surg Surg 1984; 30: 1783-9. 1994; 40: 622-4. 36. Mori K, Nagato T, Ogase H, et al. A case of ameloblastic fi- 55. Tatemoto Y, Yamamoto N, Onojima M, et al. Ameloblastic broma in an infant. Light and electron microscopic observa- fibroma: growth potentiality of odontogeic epithelium and tions. Jpn J Oral Maxillofac Surg 1985; 31: 796-806. coexpression of intermediate filament proteins in fibroma- 37. Sadamori H, Nagahata S, Takagi S, et al. A case of tous cells. J Oral Pathol 1988; 17: 168-74. ameloblastic fibroma. Jpn J Oral Maxillofac Surg 1985; 31: 56. Ookubo A, Mukai H, Yamashita M, et al. A case of 1094-8. ameloblastic fibroma occurring in the mandible. J Jpn 38. Ueda A, Kage T, Yoshida J, et al. A case of ameloblastic fi- Stomatol Soc 1987; 36: 273-7. broma. Light and electron-microscopic observation. Jpn J 57. Huebsch RF and Stephenson TD. Recurrent ameloblastic fi- Oral Maxillofac Surg 1986; 32: 848-53. broma in a 3-year-old boy. Oral Surg 1956; 9: 707-14. 39. Fuse H, Kanehira M, Fuse S, et al. A case of ameloblastic 58. Carr RF, Halperin V, Wood C, et al. Recurrent ameloblastic fibroma. J Aichi Med Univ Assoc 1988; 16: 83-90. fibroma. Oral Surg 1970; 29: 85-90. 40. Kasahara K, Kobayashi I, Fujiwara T, et al. Ameloblastic fi- 59. Gotjamanos T. Intracellualr collagen in recurrent broma treated by “dredging method”: report of a case. ameloblastic fibroma. J Oral Pathol 1979; 8: 277-83. Hokkaido J Dent Sci 1992; 12: 40-7. 60. Sawyer DR, Nwoku AL and Mosadomi A. Recurrent 41. Takaya K, Kimura K, Tsushima T, et al. A case of ameloblastic ameloblastic fibroma. Report of two cases. Oral Surg 1982; fibroma. Jpn J Oral Maxillofac Surg 1992; 38: 142-3. 53: 19-23. Oral Med Pathol 7 (2002) 59

61. Monteil RA, Le Bas V, Favot C, et al. Stereologic analysis of Maxillofac Surg 1985; 43: 289-92. histologic parameters of a twice-recurrent ameloblastic fi- 71. Baroni CB, Farneti M, Stea S, et al. Ameloblastic fibroma broma. Oral Surg Oral Med Oral Pathol 1986; 61: 168-72. and impacted mandibular first molar. A case report. Oral 62. Seldin SD. Ameloblastoma in young patients: report of two Surg Oral Med Oral Pathol 1992; 73: 548-9. cases. J Oral Surg 1961; 19: 508-12. 72. Junquera LM, Albertos JM, Floriano P, et al. Ameloblastic 63. Trott JR. Ameloblastic fibroma. Case report. Br J Oral Surg fibroma: report of two cases. Int J Pediatr Dent 1995; 5: 181- 1967; 5: 11-5. 6. 64. Gardner DG, Smith FA and Weinberg S. Ameloblastic fi- 73. McGuinness NJ, Faughnan T, Bennani F, et al. Ameloblastic broma. A benign tumour treatable by curettage. J Can Dent fibroma of the anterior maxilla presenting as a complication Assoc 1969; 35: 306-10. of tooth eruption: a case report. J Orthod 2001; 28: 115-8. 65. Lysell L and Sund G. Ameloblastic fibroma: report of two 74. Kramer IRH, Pindborg JJ and Shear M. Histological Typing cases. Br J Oral Surg 1978; 16: 78-85. of Odontogenic Tumours. 2nd edn. Springer-Verlag, Berlin, 66. Heringer WW. Ameloblastic fibroma in the anterior maxilla: 1992. report of case. ASDC J Dent Child 1978; 45: 408-11. 75. Sciubba JJ, Fantasia JE and Kahn LB. Tumors and Cysts of 67. Nilsen R and Magnusson BC. Ameloblastic fibroma. Int J the Jaws. 3rd ser. Armed Forces Institute of Pathology, Wash- Oral Surg 1979; 8: 370-4. ington DC, 2001. 68. Bell RA, Schaffner DL and Myers DR. Ameloblastic fibroma: 76. Ide F, Kitada M, Tanaka A, et al. Ameloblastic fibroma and a case report. Pediatr Dent 1982; 4: 251-4. related lesions: histological variability and potentially diag- 69. Cataldo E and Giunta JL. A clinico-pathological presenta- nostic pitfall. Hosp Dent (Tokyo) 2002; 14: 15-21. tion. J Mass Dent Soc 1984; 33: 158. 70. Young AH. Ameloblastic fibroma in an infant. J Oral (Accepted for publication March 15, 2002)