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The aggressive odontogenic fibroma: Report of a case
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KINNEY ET AL
14. Appenzeller J, WeitznerS, LongGW: Hepatocellular carcinoma metastatic to the mandible: Report of a case and review of the literature. J Oral Surg 29:668, 1971 15. McDaniel RK, Luna MA, Stimson PG : Metastatic tumors in the jaw. Oral Surg Oral Med Oral Pathol 31:380, 1971 16. Dick A, Mead SG, Mensh M, et al: Primary hepatoma with rnetastatis to the mandible. Am J Surg 94:846, 1957 17. Cernea P, Creepy CL, Chome J, et al: Metastase mandibulaire d'un epithelioma primitifdu foie. Rev StomatoI64:589, 1963 18. Lapeyrolerie FM, Manhold JH : Hepatoma metastatic to the gingiva. Oral Surg Oral Med Oral Pathol 18:365, 1964 19. Franchebois P, Laux M,Souyris F: Metastase mandibulaired'un hepatoma malin. Rev StomatoI66:155, 1966 20. Radden BG, Reade PC: Gingival metastasis from a hepatoma. Oral Surg Oral Med Oral Patho121 :621, 1966 21. Lund BA, Soule EH, Moertel CG: Hepatocellular carcinoma with metastasis to gingival mucosa: Report of a case. J Oral Surg 28:604, 1970 22. Lepesteur J, Dinhhy T, Vaillant JM, et al: Metastases mandibulaire des hcpatomes. Apropos d'un nouveau cas et revue de la Iitterature. Rev Stornatol 74:533, 1973 23. Muldoon CJ: A hepatocarcinorna with osseous metastases. J Laryngol Otol 88:891, 1974
24. Yoshida Y, Tsukada T , Yoshinari M, ct al: Two cases of metastatic tumors to the mouth. Jpn J Oral Surg 22:534, 1976 25. Kuga Y, Kitamura A, Kusaba I, et al: Primary liver cancer with metastases to gingiva: Report of a casco Jpn J Oral Surg 22: 541, 1976 26. Cadenat H, Fabert G, Combelles R, et al: Metastase mandibulaire revelatricce d'un cancer prirnitif dufoie. Rev Stomatol Chir Maxillofac 991,1976 27. Goveia G, Bahn S: Asymptomatic hepatocellular carcinoma metastatic to the mandible. Oral Surg Oral Med Oral Pathol 45:424, 1978 28. Wedgwood D, Rusen D, Balk S: Gingival metastases from primary hepatocellular carcinoma. Oral Surg Oral Med Oral Patho147:263, 1979 29. Kinoshita F, Yoshida Y, Ogata K, et al: A case of hepatocellular carcinoma with mandibular metastasis. Jpn J Oral Surg 26: 1706, 1980 (abstr) 30. Kanazawa H, Sato K: Gingival metastasis from primary hepatocellular carcinoma. J Oral Maxillofac Surg 47:987, 1989 31. Marker P, Claussen PP: Metastases to the mouth and jaws from hepatocellular carcinomas. Int J Oral Maxillofac Surg 20:371, 1991
J Oral Maxillofac Surg 51 :321·324.1993
The Aggressive Odontogenic Fibroma: Report of a Case LISA A. KINNEY, DDS,* JOHN BRADFORD, DMD,t MARTIN COHEN, MD,t AND ROBERT S. GLICKMAN, DMD§
The diagnosis and surgical management of odontogenic tumors can present significant problems for the pathologist and surgeon because ofdifferences that can arise between the microscopic features and the clinical behavior ofthese lesions. This is especially true with regard to the odontogenic fibroma. The following case report describes a lesion initially diagnosed as an odontogenic fibroma that developed unusual micro-
scopic features over the course oftreatment and showed a clinical behavior that, to date, had not been reported in the literature. The case also illustrates the difficulty in establishing a definitive microscopic diagnosis and treatment plan for such lesions.
* Assistant Professor, Department of Oral and Maxillofacial Surgery, New York University College of Dentistry, New York, NY. t Former Chief Resident, Department of Oral and Maxillofacial Surgery, Bellevue Hospital Center, In Private Practice, Philadelphia, PA. t Associate Professor Oral Pathology, New York University College of Dentistry, New York, NY. § Director, Advanced Education Program, Oral and Maxillofacial Surgery, Bellevue Hospital Center/New York University College of Dentistry, New York, NY. Address correspondence and reprint requests to Dr Glickman: New York University, Department of Oral and Maxillofacial Surgery, 345 E 24th St, New York, NY 10010. © 1993 American Association of Oral and Maxillofacial Surgeons 0278-2391/93/5103-0020$3.00/0
FIGURE I. Periapical radiograph showing iII-defined radiolucency around the mandibular right second molar 3 months before endodontic treatment.
322
AGGRESSIVE ODONTOGENIC FIBROMA
FIGURE 2. Panoramic radiograph at completion of root canal therapy showing irregular 2.5-cm rad iolucency about the apex of the mandibular right second molar.
FIGURE 4. Photomicrograph ofthc biopsy specimen adherent to the extracted tooth showing morphology consistent with odontogenic fibroma (hematoxylin-eosin stain, original magnification X100).
A 66-year-old woman was referred from the College of Dentistry in November 1988 because of an asymptomatic, :l.S-cm, irregular radiolucent area at the apex of the right mandibular second molar that had not responded to conventional root canal therapy (Figs 1,2). The medical, family, and social history and review of systems were unremarkable. Physical examination revealed a slight buccal expansion of the right posterior mandible lateral to the second molar. After a negative needle aspiration, an incisional biopsy was performed that included specimens from the buccal cortical plate, the involved molar tooth, and a 1.3 X O.7-cm portion of the intraosseous lesion. The neoplasm was tan in color with a slightly hemorrhagic appearance and rubbery texture. The cut surface had a gritty consistency. The preliminary microscopic diagnosis was a nonspecific benign fibro-osseous lesion (Fig 3). Because of the clinical presentation of the lesion and its variable histomorphology, following review by several oral pathologists, consultation with the Armed Forces Institute of Pathology was requested. Their initial diagnosis, based
on the ill-defined radiographic and microscopic appearance, was osteom yelitis, possibly superimposed on another underlying lesion. Of note, several nests of epitheliod cells were identified. Further review of the specimens, especially those directly attached to the root surface, resulted in a finalpreoperative diagnosis of odontogenic fibroma (Fig 4). Based on this diagnosis, the patient was taken to the operating room, where the tumor was enucleated and the first molar was extracted . It separated easily from the adjacent bone and the contents of the inferior alveolar canal. The osseous defect was curetted. The microscopic findings in the specimen again were consistent with a diagnosis of odontogenic fibroma. The patient was followed weekly for 6 weeks after discharge and then on a monthly basis for 3 months without clinical or radiographic evidence of recurrence. As the treatment was in agreement with the currently recommended management of this lesion, the patient was discharged and placed on recall. The patient was lost to follow-up until December 1989 when she was seen at the Oral and Maxillofacial Surgery Clinic with a painful right facial swelling and paresthesia of the lower right lip and chin. A panoramic radiograph revealed an ill-defined, multilocular, radiolucent lesion extending from the right ascending ramus posteriorly to the right parasymphyseal region anteriorly (Fig 5). No intraoral perforations
FIGURE 3. Photomicrograph of the initial biopsy specimen. A fibrous stroma and irregular cords of epithelial cells are seen (hematoxylin-eosin stain, original magnification X2(0).
FIGURE 5. Panoramic radiograph 13 months after initial surgery showing the recurrent lesions extending into the right ramus and to the right parasyrnphyseal region anteriorly.
Report of Case
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FIGURE 8. Postoperative panoramic radiograph showing area of resection and the reconstruction plate in place.
Discussion
FIGURE 6. cr scan with contrast showing the lesion encompassing the entire right mandible with buccal cortical expansion and lingual and buccal perforation.
were detected, and there was no evidence of ulceration. The buccal cortex was markedly expanded, but there was no lingual expansion. Laboratory studies were normal except for a slightly elevated alkaline phosphatase. Routine chest radiographs were negative. A computed tomogram (Cf) with contrast demonstrated that the lesion encompassedthe entire right mandible anteriorly to the parasymphysis region with areas of buccal and lingual erosion and perforation (Fig 6). Radionuclide scanning showed increased uptake only in the tumor mass. An incisional biopsy was done and the diagnosis was recurrent odontogenic fibroma (WHO type) (Fig 7). Given the clinical behavior of the lesion, a right hemimandibulectomy was performed, with placement of a mandibular reconstruction plate (Fig 8). The Armed Forces Institute of Pathology diagnosisof the specimen obtained from the surgerywas aggressive clear-cell epithelial neoplasm, probably odontogenic in origin (Fig 9). Further medical workup of the patient revealed no other tumor site.
FIGURE 7. Photomicrograph of incisional biopsy at the second surgery again showing a fibrous tissue stroma and clusters of epithelial cells (hematoxylin-eosin stain, original magnification X2(0).
Little is known about the biologic behavior of the odontogenic. fibroma because so few have been reported, especially as intraosseous lesions.'? To date, based on the specific diagnostic criteria of Handlers et ai, approximately 40 cases of central odontogenic fibroma have been documented." The present state of knowledge suggests that the odontogenic fibroma should be completely enucleated or curetted. It also indicates that the microscopic pattern has no correlation with clinical behavior. Previous studies do not reveal an instance of infiltration of cancellous bone by such a tumor and therefore this precluded resection of uninvolved bone.' This case, however, suggests that a lesion diagnosed as odontogenic fibroma may be infiltrative and involve cortical and cancellous bone of the mandible in a manner not previously reported. This case may have been dimorphic at the outset, with clear cells not seen on any ofthe biopsy specimens. This portion of the tumor then became the dominant cell type by the time of the resection and little of the
FIGURE 9. Photomicrograph of the final specimen. The tissue consists of sheets of clear cells compatible with a final diagnosis of clear-cell odontogenic tumor or clear-cell carcinoma of odontogenic origin (hematoxyIin-eosin stain, original magnification X2(0).
324
original cell type remained. If, in fact, these lesions form a continuum, then the current case would represent an example that initially presented with the morphology of an odontogenic fibroma but the behavior of a clear-cell odontogenic tumor. Histomorphology that verified the diagnosis of clear-cell odontogenic tumor was only discernible on examination of the resection specimen. As reported by various investigators, the quantity of odontogenic epithelium is unrelated to rate of recurrence of odontogenic fibromas.v!' The microscopic pattern and morphology are also not thought to have a correlation with clinical behavior. .Differentiation between the odontogenic fibroma and the myxofibroma must be made; the latter being devoid of any epithelial component and containing myxoid stroma. Although both entities can be locally infiltrative and lack a capsule, the odontogenic fibroma exhibits a more limited growth potential and is treated by enucleation or curettage. In our case, the distinction between these two entities, and ultimately the diagnosis of clear-cell odontogenic tumor, only became apparent over time as the lesion demonstrated a changing microscopic character and destructive clinical behavior. Those cells that could be identified as clear cells were obvious only in the final specimen. The value of enucleation and curettage in treating this group of odontogenic tumors should be considered on an individual case basis.'? Though the abundance of clinical information suggestsconservative treatment, in rare cases these benign lesions may enlarge and
AGGRESSIVE ODONTOGENIC FIBROMA
change character, causing rapid bone destruction. This group of tumors should be considered for resection depending on the size and location , if the clinical behavior is unusually aggressive, or the microseopic appearance suggests a clear-cell or myxomatous variant.
References I. Bhaskar SN: Synopsis of Oral Pathology (ed 7). St Louis, MO, Mosby, pp 282-284 2. Gardner D: The central odontogenic fibroma : An attempt at clarification . Oral Surg Oral Med Oral Pathol 50:425, 1980 Wesley RK, Wysocki GP, Mintz SM: The central odontogenic fibroma: Clinical and morphologic studies . Oral Surg 40:235245, 1975. 4. Dahl EC, Wolfsen SH, Haugen JC: Central odontogenic fibroma: Review of literature and report of cases. J Oral Surg 39: 120, 1981 5. Handlers JP, Abrams AM, Melrose RJ, et aI: Central Odontogenic fibroma: Clinicopathologic features of 19 cases and review of the literature. J Oral Maxillofacia Surg 49:46, 1991 6. Jonew GM, Eveson JW , Shepherd JP: Central odontogenic fibroma. A report of two controversial cases illustrating diagnostic dilemmas. Br J Oral Maxillofac Surg 27:406, 1989 7. Doyle JL, Lamster JB, Baden E: Odontogenic fibroma of the complex (WHO) type: Report of six cases, J Oral Maxillofac Surg 43:666-674, 1985. 8. Dunlap CL, Barker BF:Central odontogenic fibroma of the WHO type. Oral Surg Oral Med Oral Pathol 57:390, 1984 9. Janss en JH, Blijdorp PA: Central odontogenic fibroma: A case report. J Maxillofac Surg 13:236, 1985 10. Schofield ID: Central odontogenic fibroma: Report of a case. J Oral Surg 39:218, 1981 I I. Heimdol A, IsacssonG , Nilsson L: Recurrent central odontogenic fibroma . Oral Surg Oral Med Oral Pathol 50:140, 1980 12. Foley W, Terry B, Jaco way J: Malignant transformation of an odontogenic keratocyst: Report of a case. J Oral Maxillofac Surg 49:768, 1991
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KINNEY ET AL
14. Appenzeller J, WeitznerS, LongGW: Hepatocellular carcinoma metastatic to the mandible: Report of a case and review of the literature. J Oral Surg 29:668, 1971 15. McDaniel RK, Luna MA, Stimson PG : Metastatic tumors in the jaw. Oral Surg Oral Med Oral Pathol 31:380, 1971 16. Dick A, Mead SG, Mensh M, et al: Primary hepatoma with rnetastatis to the mandible. Am J Surg 94:846, 1957 17. Cernea P, Creepy CL, Chome J, et al: Metastase mandibulaire d'un epithelioma primitifdu foie. Rev StomatoI64:589, 1963 18. Lapeyrolerie FM, Manhold JH : Hepatoma metastatic to the gingiva. Oral Surg Oral Med Oral Pathol 18:365, 1964 19. Franchebois P, Laux M,Souyris F: Metastase mandibulaired'un hepatoma malin. Rev StomatoI66:155, 1966 20. Radden BG, Reade PC: Gingival metastasis from a hepatoma. Oral Surg Oral Med Oral Patho121 :621, 1966 21. Lund BA, Soule EH, Moertel CG: Hepatocellular carcinoma with metastasis to gingival mucosa: Report of a case. J Oral Surg 28:604, 1970 22. Lepesteur J, Dinhhy T, Vaillant JM, et al: Metastases mandibulaire des hcpatomes. Apropos d'un nouveau cas et revue de la Iitterature. Rev Stornatol 74:533, 1973 23. Muldoon CJ: A hepatocarcinorna with osseous metastases. J Laryngol Otol 88:891, 1974
24. Yoshida Y, Tsukada T , Yoshinari M, ct al: Two cases of metastatic tumors to the mouth. Jpn J Oral Surg 22:534, 1976 25. Kuga Y, Kitamura A, Kusaba I, et al: Primary liver cancer with metastases to gingiva: Report of a casco Jpn J Oral Surg 22: 541, 1976 26. Cadenat H, Fabert G, Combelles R, et al: Metastase mandibulaire revelatricce d'un cancer prirnitif dufoie. Rev Stomatol Chir Maxillofac 991,1976 27. Goveia G, Bahn S: Asymptomatic hepatocellular carcinoma metastatic to the mandible. Oral Surg Oral Med Oral Pathol 45:424, 1978 28. Wedgwood D, Rusen D, Balk S: Gingival metastases from primary hepatocellular carcinoma. Oral Surg Oral Med Oral Patho147:263, 1979 29. Kinoshita F, Yoshida Y, Ogata K, et al: A case of hepatocellular carcinoma with mandibular metastasis. Jpn J Oral Surg 26: 1706, 1980 (abstr) 30. Kanazawa H, Sato K: Gingival metastasis from primary hepatocellular carcinoma. J Oral Maxillofac Surg 47:987, 1989 31. Marker P, Claussen PP: Metastases to the mouth and jaws from hepatocellular carcinomas. Int J Oral Maxillofac Surg 20:371, 1991
J Oral Maxillofac Surg 51 :321·324.1993
The Aggressive Odontogenic Fibroma: Report of a Case LISA A. KINNEY, DDS,* JOHN BRADFORD, DMD,t MARTIN COHEN, MD,t AND ROBERT S. GLICKMAN, DMD§
The diagnosis and surgical management of odontogenic tumors can present significant problems for the pathologist and surgeon because ofdifferences that can arise between the microscopic features and the clinical behavior ofthese lesions. This is especially true with regard to the odontogenic fibroma. The following case report describes a lesion initially diagnosed as an odontogenic fibroma that developed unusual micro-
scopic features over the course oftreatment and showed a clinical behavior that, to date, had not been reported in the literature. The case also illustrates the difficulty in establishing a definitive microscopic diagnosis and treatment plan for such lesions.
* Assistant Professor, Department of Oral and Maxillofacial Surgery, New York University College of Dentistry, New York, NY. t Former Chief Resident, Department of Oral and Maxillofacial Surgery, Bellevue Hospital Center, In Private Practice, Philadelphia, PA. t Associate Professor Oral Pathology, New York University College of Dentistry, New York, NY. § Director, Advanced Education Program, Oral and Maxillofacial Surgery, Bellevue Hospital Center/New York University College of Dentistry, New York, NY. Address correspondence and reprint requests to Dr Glickman: New York University, Department of Oral and Maxillofacial Surgery, 345 E 24th St, New York, NY 10010. © 1993 American Association of Oral and Maxillofacial Surgeons 0278-2391/93/5103-0020$3.00/0
FIGURE I. Periapical radiograph showing iII-defined radiolucency around the mandibular right second molar 3 months before endodontic treatment.
322
AGGRESSIVE ODONTOGENIC FIBROMA
FIGURE 2. Panoramic radiograph at completion of root canal therapy showing irregular 2.5-cm rad iolucency about the apex of the mandibular right second molar.
FIGURE 4. Photomicrograph ofthc biopsy specimen adherent to the extracted tooth showing morphology consistent with odontogenic fibroma (hematoxylin-eosin stain, original magnification X100).
A 66-year-old woman was referred from the College of Dentistry in November 1988 because of an asymptomatic, :l.S-cm, irregular radiolucent area at the apex of the right mandibular second molar that had not responded to conventional root canal therapy (Figs 1,2). The medical, family, and social history and review of systems were unremarkable. Physical examination revealed a slight buccal expansion of the right posterior mandible lateral to the second molar. After a negative needle aspiration, an incisional biopsy was performed that included specimens from the buccal cortical plate, the involved molar tooth, and a 1.3 X O.7-cm portion of the intraosseous lesion. The neoplasm was tan in color with a slightly hemorrhagic appearance and rubbery texture. The cut surface had a gritty consistency. The preliminary microscopic diagnosis was a nonspecific benign fibro-osseous lesion (Fig 3). Because of the clinical presentation of the lesion and its variable histomorphology, following review by several oral pathologists, consultation with the Armed Forces Institute of Pathology was requested. Their initial diagnosis, based
on the ill-defined radiographic and microscopic appearance, was osteom yelitis, possibly superimposed on another underlying lesion. Of note, several nests of epitheliod cells were identified. Further review of the specimens, especially those directly attached to the root surface, resulted in a finalpreoperative diagnosis of odontogenic fibroma (Fig 4). Based on this diagnosis, the patient was taken to the operating room, where the tumor was enucleated and the first molar was extracted . It separated easily from the adjacent bone and the contents of the inferior alveolar canal. The osseous defect was curetted. The microscopic findings in the specimen again were consistent with a diagnosis of odontogenic fibroma. The patient was followed weekly for 6 weeks after discharge and then on a monthly basis for 3 months without clinical or radiographic evidence of recurrence. As the treatment was in agreement with the currently recommended management of this lesion, the patient was discharged and placed on recall. The patient was lost to follow-up until December 1989 when she was seen at the Oral and Maxillofacial Surgery Clinic with a painful right facial swelling and paresthesia of the lower right lip and chin. A panoramic radiograph revealed an ill-defined, multilocular, radiolucent lesion extending from the right ascending ramus posteriorly to the right parasymphyseal region anteriorly (Fig 5). No intraoral perforations
FIGURE 3. Photomicrograph of the initial biopsy specimen. A fibrous stroma and irregular cords of epithelial cells are seen (hematoxylin-eosin stain, original magnification X2(0).
FIGURE 5. Panoramic radiograph 13 months after initial surgery showing the recurrent lesions extending into the right ramus and to the right parasyrnphyseal region anteriorly.
Report of Case
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KINNEY ET AL
FIGURE 8. Postoperative panoramic radiograph showing area of resection and the reconstruction plate in place.
Discussion
FIGURE 6. cr scan with contrast showing the lesion encompassing the entire right mandible with buccal cortical expansion and lingual and buccal perforation.
were detected, and there was no evidence of ulceration. The buccal cortex was markedly expanded, but there was no lingual expansion. Laboratory studies were normal except for a slightly elevated alkaline phosphatase. Routine chest radiographs were negative. A computed tomogram (Cf) with contrast demonstrated that the lesion encompassedthe entire right mandible anteriorly to the parasymphysis region with areas of buccal and lingual erosion and perforation (Fig 6). Radionuclide scanning showed increased uptake only in the tumor mass. An incisional biopsy was done and the diagnosis was recurrent odontogenic fibroma (WHO type) (Fig 7). Given the clinical behavior of the lesion, a right hemimandibulectomy was performed, with placement of a mandibular reconstruction plate (Fig 8). The Armed Forces Institute of Pathology diagnosisof the specimen obtained from the surgerywas aggressive clear-cell epithelial neoplasm, probably odontogenic in origin (Fig 9). Further medical workup of the patient revealed no other tumor site.
FIGURE 7. Photomicrograph of incisional biopsy at the second surgery again showing a fibrous tissue stroma and clusters of epithelial cells (hematoxylin-eosin stain, original magnification X2(0).
Little is known about the biologic behavior of the odontogenic. fibroma because so few have been reported, especially as intraosseous lesions.'? To date, based on the specific diagnostic criteria of Handlers et ai, approximately 40 cases of central odontogenic fibroma have been documented." The present state of knowledge suggests that the odontogenic fibroma should be completely enucleated or curetted. It also indicates that the microscopic pattern has no correlation with clinical behavior. Previous studies do not reveal an instance of infiltration of cancellous bone by such a tumor and therefore this precluded resection of uninvolved bone.' This case, however, suggests that a lesion diagnosed as odontogenic fibroma may be infiltrative and involve cortical and cancellous bone of the mandible in a manner not previously reported. This case may have been dimorphic at the outset, with clear cells not seen on any ofthe biopsy specimens. This portion of the tumor then became the dominant cell type by the time of the resection and little of the
FIGURE 9. Photomicrograph of the final specimen. The tissue consists of sheets of clear cells compatible with a final diagnosis of clear-cell odontogenic tumor or clear-cell carcinoma of odontogenic origin (hematoxyIin-eosin stain, original magnification X2(0).
324
original cell type remained. If, in fact, these lesions form a continuum, then the current case would represent an example that initially presented with the morphology of an odontogenic fibroma but the behavior of a clear-cell odontogenic tumor. Histomorphology that verified the diagnosis of clear-cell odontogenic tumor was only discernible on examination of the resection specimen. As reported by various investigators, the quantity of odontogenic epithelium is unrelated to rate of recurrence of odontogenic fibromas.v!' The microscopic pattern and morphology are also not thought to have a correlation with clinical behavior. .Differentiation between the odontogenic fibroma and the myxofibroma must be made; the latter being devoid of any epithelial component and containing myxoid stroma. Although both entities can be locally infiltrative and lack a capsule, the odontogenic fibroma exhibits a more limited growth potential and is treated by enucleation or curettage. In our case, the distinction between these two entities, and ultimately the diagnosis of clear-cell odontogenic tumor, only became apparent over time as the lesion demonstrated a changing microscopic character and destructive clinical behavior. Those cells that could be identified as clear cells were obvious only in the final specimen. The value of enucleation and curettage in treating this group of odontogenic tumors should be considered on an individual case basis.'? Though the abundance of clinical information suggestsconservative treatment, in rare cases these benign lesions may enlarge and
AGGRESSIVE ODONTOGENIC FIBROMA
change character, causing rapid bone destruction. This group of tumors should be considered for resection depending on the size and location , if the clinical behavior is unusually aggressive, or the microseopic appearance suggests a clear-cell or myxomatous variant.
References I. Bhaskar SN: Synopsis of Oral Pathology (ed 7). St Louis, MO, Mosby, pp 282-284 2. Gardner D: The central odontogenic fibroma : An attempt at clarification . Oral Surg Oral Med Oral Pathol 50:425, 1980 Wesley RK, Wysocki GP, Mintz SM: The central odontogenic fibroma: Clinical and morphologic studies . Oral Surg 40:235245, 1975. 4. Dahl EC, Wolfsen SH, Haugen JC: Central odontogenic fibroma: Review of literature and report of cases. J Oral Surg 39: 120, 1981 5. Handlers JP, Abrams AM, Melrose RJ, et aI: Central Odontogenic fibroma: Clinicopathologic features of 19 cases and review of the literature. J Oral Maxillofacia Surg 49:46, 1991 6. Jonew GM, Eveson JW , Shepherd JP: Central odontogenic fibroma. A report of two controversial cases illustrating diagnostic dilemmas. Br J Oral Maxillofac Surg 27:406, 1989 7. Doyle JL, Lamster JB, Baden E: Odontogenic fibroma of the complex (WHO) type: Report of six cases, J Oral Maxillofac Surg 43:666-674, 1985. 8. Dunlap CL, Barker BF:Central odontogenic fibroma of the WHO type. Oral Surg Oral Med Oral Pathol 57:390, 1984 9. Janss en JH, Blijdorp PA: Central odontogenic fibroma: A case report. J Maxillofac Surg 13:236, 1985 10. Schofield ID: Central odontogenic fibroma: Report of a case. J Oral Surg 39:218, 1981 I I. Heimdol A, IsacssonG , Nilsson L: Recurrent central odontogenic fibroma . Oral Surg Oral Med Oral Pathol 50:140, 1980 12. Foley W, Terry B, Jaco way J: Malignant transformation of an odontogenic keratocyst: Report of a case. J Oral Maxillofac Surg 49:768, 1991
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