Peripheral ameloblastoma: A case report Hercellio Martelli-J unior, DDS, PhD,a Leandro N. Souza, DDS, MSc,b Luis Antonio Nogueira Santos, b DDS, MSc, Ma´rio R. Melo-Filho, DDS, MSc,c Alfredo M. B. De Paula, DDS, PhD,a Montes Claros, Brazil STATE UNIVERSITY OF MONTES CLAROS
Peripheral ameloblastoma is a rare odontogenic soft tissue tumor, derived from epithelial and/or mesenchymal elements being part of the tooth-forming apparatus. The lesion responses for approximately 1% to 5% of all cases of ameloblastoma affecting alveolar mucosa and gingiva occur, mainly, in the middle age. This article describes a case of peripheral ameloblastoma involving a 20-year-old male located in the (upper/lower, vestibular/buccal) gingiva. After the case presentation, clinical and microscopic findings are discussed. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2005;99:E31-3)
Odontogenic tumors are lesions derived from epithelial or mesenchymal elements, or both, that are part of the tooth-forming apparatus. They are found exclusively in the mandible, maxilla, and gingiva on rare occasions.1 Peripheral ameloblastoma (PA) is a rare odontogenic soft tissue tumor2,3 that is reported to account for approximately 1% to 5% of all ameloblastomas.4 It was first described in the literature by Kuru in 1911.5 The tumor is distinguished from the intraosseous counterpart by its extraosseous location and less aggressive behavior, causing mild saucerization of adjacent bone in some instances, but without actual infiltration into the marrow spaces.6,7 Gurol and Burkes2 reviewed 205 ameloblastomas from 1956 to 1994, and only 8 were PA. This tumor seems to have a predilection for the dentulous areas as compared to the edentulous ones.8 The PA is thought to arise from rests of the dental lamina or from basal cells of the surface epithelium.2,4 Histologically, the PA resembles the intraosseous form, consisting of a proliferation of ameloblastic epithelium set in a dense collagenous stroma.6,7 PA is usually slow growing and asymptomatic, and it is possible to observe a sessile, broad, or pedunculated 1- to 2-cm lesion covered by normal mucosa, and with a firm consistency, smooth surface, and pink color.5,9 Superficial
Titular Professor, Oral Pathology Area, Dentistry Department, State University of Montes Claros, Minas Gerais, Brazil. b Assistant Professor, Oral Pathology and Radiology Area, Dentistry Department, State University of Montes Claros, Minas Gerais, Brazil. c Adjunct Professor, Oral Pathology Area, Dentistry Department, State University of Montes Claros, Minas Gerais, Brazil. Received for publication Jul 6, 2004; returned for revision Oct 19, 2004; accepted for publication Nov 22, 2004. 1079-2104/$ - see front matter Ó 2005 Elsevier Inc. All rights reserved. doi:10.1016/j.tripleo.2004.11.016
bone resorption is occasionally associated with the lesion.7 The diagnostic criteria of PA include origin from the overlying epithelium, presence of odontogenic epithelium islands in the lesion, and lack of a potential to bone infiltration.2 The recommended treatment is wide excision down through periosteum.4,6 Recurrence has been noted infrequently.3,4 This report describes the clinical and microscopic features of PA.
CASE REPORT A 20-year-old male nonsmoker presented with an asymptomatic sessile 2.0-cm pink lesion on the lingual gingiva of the right posterior region (Fig 1). There were no significant radiographic findings. The patient related a nodule slowly growing for about 4 months and the clinical features revealed a lesion covered by normal mucosa with a smooth surface and firm consistency. All the involved teeth were vital. The clinical diagnosis of peripheral ossifying fibroma was established and an excisional biopsy with narrow margin including the underlying periosteum was performed under local anesthesia. The histological exam showed at low magnification the presence of a lesion covered by hyperplastic epithelium, exhibiting transition to a tumor composed of islands that consisted of a peripheral layer of palisaded columnar cells with polarized nuclei surrounding a central zone of spindle cells (Fig 2, A). The tumor extended close to a deep surgical margin. The diagnosis was peripheral ameloblastoma. No recurrence was observed in a 1-year follow-up.
DISCUSSION In the English literature approximately 64 cases of PA were reported. In addition, there are 43 cases recorded in the Japanese literature since 1967 and 1 case documented in the Greek literature.10 Reichart et al,11 in a review of 3677 cases of ameloblastoma, found that only 73 cases (2%) were PA. E31
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Fig 1. Clinical aspects of the lingual gingiva of the right posterior region.
Gurol and Burkes2 reviewed 8 cases of PA that were archived at the University of North Carolina School of Dentistry Oral Pathology Biopsy Service between 1956 and 1994. Radiographic cupping of the underlying bone was only observed in 1 case, and no recurrences were noted. However, 1 patient developed a new lesion in a separate site 7 years after the initial presentation. Lin et al4 documented a case from the dental department of Tao-Yuan General Hospital in Taiwan in 1981 in which an 83-year-old woman presented with an aggressive PA of the mandibular posterior alveolar ridge. The authors claimed that the lesion metastasized to the supraclavicular lymph nodes and brain. The patient died 1 week after the initial diagnosis; no confirmative autopsy was performed because of local custom. The rapid metastasis of the tumor and the sudden death of the patient make the diagnosis of the original lesion as a PA unlikely. The differential diagnosis must be made with fibrous nodules, gingival tumors, peripheral odontogenic fibromas, peripheral ossifying fibromas, pyogenic granuloma, peripheral giant-cell granuloma, and other peripheral hyperplastic swellings superficial to the alveolar ridge. PA may appear as an erythematous plaque or, rarely, as a polypoid and papillary lesion. The differential diagnosis should also include the very rare peripheral squamous odontogenic tumor.12 One of the main problems regarding PA is its possible origin. The 2 main theories are the following: (1) origin from the extraosseous epithelial remnants of dental lamina and its organ derivatives within the underlying connective tissue; (2) origin from the basal cell layer of the oral mucosa, which is believed to have odontogenic potential.6,8 Those lesions that are entirely separated from the overlying surface epithelium probably arise from odontogenic remnants,5 but this hypothesis can be
Fig 2. A, Islands, strands, and medullary arrangements of follicular ameloblastoma arrangements against a background stroma of fibrous connective tissue and in proximity to surface epithelium. B, The arrows show small spaces cysts within islands of neoplastic epithelium (red).
questioned if there is continuity between tumor and surface epithelium.13 This fact could suggest a basal cell origin of the ameloblastoma, however it could simply represent a fusion of the underlying tumor with the epithelium.5 Recurrences are rare, even in conservative surgeries with the resection of a small amount of normal tissue.9,11 Despite the nonaggressive course and low recurrence rate of the PA, long-term follow-up is absolutely necessary.10 Wettan et al10 showed PA recurring as dysplasia. Although infrequent, the possibility of recurrence and the association with, or the progression into, dysplasias and malignancies cannot be overlooked.10 In the case presented, there was no evidence of malignancy and no signs of recurrence 1 year after treatment. REFERENCES 1. Regezi JA, Sciubba JJ. Oral pathology—Clinical pathologic correlations. 3rd ed. Philadelphia: W.B. Saunders Company; 1999. p. 323.
OOOOE Volume 99, Number 5 2. Gurol M, Burkes EJ Jr. Peripheral ameloblastoma. J Periodontol 1995;66:1065-8. 3. El-Mofty SK, Gerard NO, Farish SE, Rodu B. Peripheral ameloblastoma: a clinical and histologic study of 11 cases. J Oral Maxillofac Surg 1991;49:970-6. 4. Lin SC, Lieu CM, Hahn LJ, Kwan HW. Peripheral ameloblastoma with metastasis. Int J Oral Maxiloffac Surg 1987;16: 202-6. 5. Zhu EX, Okada N, Takagi M. Peripheral ameloblastoma: case report and review of literature. J Oral Maxiloffac Surg 1995;53:590-4. 6. Redman RS, Keegan BP, Spector CJ, Patterson RH. Peripheral ameloblastoma with unusual mitotic activity and conflicting evidence regarding histogenesis. J Oral Maxillofac Surg 1994;52: 192-7. 7. Baden E, Doyle JL, Petriella V. Malignant transformation of peripheral ameloblastoma. Oral Surg Oral Med Oral Pathol 1993;75:214-9. 8. Mintz S, Anavi Y, Sabes WR. Peripheral ameloblastoma of the gingiva. J Periodontol 1990;61:649-52. 9. El-Mofty SK, Gerard NO, Farish SE, Rodu B. Peripheral ameloblastoma: a clinical and histologic study of 11 cases. J Oral Maxillofac Surg 1991;48:970-4.
Martelli-J unior et al E33 10. Wettan HL, Patella PA, Freedman PD. Peripheral ameloblastoma: review of the literature and report of recurrence as severe dysplasia. J Oral Maxillofac Surg 2001;59:811-5. 11. Reichart PA, Philipsen HP, Sonner S. Ameloblastoma: biological profile of 3677 cases. Oral Oncol Eur J Cancer 1993; 31:86-99. 12. Orsini G, Fioroni M, Rubini C, Piatelli A. Peripheral ameloblastoma: a report of 2 cases. J Periodontol 2000;71:1174-6. 13. Yamamoto T, Ueta E, Yoneda K, Osaki T. Peripheral ameloblastoma: case report with immunohistochemical investigation. J Oral Maxillofac Surg 1990;48:197-200. Reprint requests: Luis Antonio Nogueira Santos, DDS, MSc Oral Pathology Area, Dentistry Department State University of Montes Claros Campus Universita´rio ‘‘Darcy Ribeiro’’ 39401-089, CP 126 Montes Claros, MG, Brazil [email protected]