Peripheral Ameloblastoma: A Case Report and Review of the Literature

Peripheral Ameloblastoma: A Case Report and Review of the Literature

Case Report—Clinical Techniques Peripheral Ameloblastoma: A Case Report and Review of the Literature Demetrick W. LeCorn, DMD,* Indraneel Bhattachary...

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Case Report—Clinical Techniques

Peripheral Ameloblastoma: A Case Report and Review of the Literature Demetrick W. LeCorn, DMD,* Indraneel Bhattacharyya, DDS, MSD,† and Frank J. Vertucci, DMD* Abstract Peripheral ameloblastoma is a rare, benign odontogenic tumor that histologically resembles an intraosseous ameloblastoma but develops in the soft tissues of the gingiva and mucosa and exhibits an innocuous clinical behavior. We report a case of a recurrent peripheral ameloblastoma in a 61-year-old man that presented as a painless swelling on the maxillary anterior labial attached gingiva. Clinical and histopathologic features of this lesion are discussed. The peripheral ameloblastoma should be included in the differential diagnosis of a gingival lesion clinically resembling any of the myriads of entities seen on the gingiva including a pyogenic granuloma, peripheral giant cell granuloma, or parulis/gumboil. We believe this case highlights the need for submitting excised tissue for microscopic examination. (J Endod 2006;32:152–154)

Key Words Gingival lesion, peripheral ameloblastoma

From the *Department of Endodontics; †Department of Oral and Maxillofacial Surgery and Diagnostic Sciences, College of Dentistry, University of Florida, Gainesville, Florida. Address requests for reprints to Dr. Indraneel Bhattacharyya, University of Florida, Department of Oral and Maxillofacial Surgery and Diagnostic Sciences, P.O. Box 100414, Gainesville, FL 32610-0414. E-mail address: [email protected] 0099-2399/$0 - see front matter Copyright © 2006 by the American Association of Endodontists. doi:10.1016/j.joen.2005.10.028


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meloblastomas overwhelmingly occur centrally within the jaws but have the potential to occur in extraosseous locations (1– 4). Although its clinical appearance varies, the peripheral ameloblastoma (PA) generally presents clinically as a slowgrowing, firm, painless mass with a sessile or pedunculated base with a smooth surface and a normal pink color. It may vary in size from 0.2 to 4.5 cm in diameter and usually has no radiographic evidence of bone involvement (2, 5). It is usually confined to the gingiva or alveolar mucosa and does not invade the underlying bone (1, 2, 5–7). However, it may cause a depression of the underlying bone or exhibit a “saucerization” or “cupping” effect because of pressure resorption caused by the lesion (1, 4, 5, 7). The PA is microscopically similar to an intraosseous ameloblastoma. The PA is less aggressive than its intraosseous counterpart (1, 2) and is thought to arise from remnants of the reduced enamel epithelium, cell rests of the dental lamina, or from basal cells of the surface epithelium (1, 2, 7, 9). It is also known by many descriptive synonyms as an extraosseous ameloblastoma, soft tissue ameloblastoma, ameloblastoma of mucosal origin, or ameloblastoma of the gingiva (7). The PA is more common in males (2:1) and lesions have a higher frequency in the mandible than in the maxilla (2.4:1). The most common site is the mandibular lingual premolar region followed by the mandibular anterior region. In the maxilla, the most common site is the soft palatal tissue adjacent to the maxillary tuberosity (2, 5). The purpose of this paper is to present a case of a PA occurring in the maxillary anterior facial gingiva.

Case Report A 61-year-old white male was referred to the University of Florida College of Dentistry, Department of Endodontics by his general dentist for evaluation and retreatment of the right maxillary lateral incisor (tooth #8) for possible failing root canal therapy and the presence of a sinus tract. The patient’s past dental records revealed that a similar lesion was noted 7 years before in the same location. This was clinically considered to be a parulis and expected to heal after endodontic therapy. Results of pulp testing of all anterior teeth at that time were equivocal. Endodontic treatment was performed on tooth #8. However, on subsequent 6-month recall, the records indicate that the lesion persisted asymptomatically and was excised but not submitted for histopathologic examination. A painless, sessile, red, smooth surfaced, slightly mobile, swelling was noted on the anterior maxillary facial attached gingiva, directly above, but not attached to, the marginal gingiva between the area of teeth #7 and #8 (Fig. 1). According to the patient, the lesion appeared approximately 1 year before and seemed to be slightly larger than the first occurrence. Both #7 and #8 had full coverage crowns with adequate margins. The surrounding gingiva exhibited normal color and texture. There was slight mobility associated with all anterior teeth. The lesion was asymptomatic and no stoma was evident. Radiographic examination revealed a well-defined 0.75 ⫻ 2.0 cm faint periradicular radiolucency apical to tooth #8, extending to the area between teeth #7 and #8 (Fig. 2). The periodontal ligament of tooth #8 appeared normal with intact lamina dura. The obturation of tooth #8 appeared to be of good quality and density. Because the lesion did not resemble a typical parulis, it was decided to excise it under local anesthesia. During excision a shallow “cupping” resorption of the underlying bone was noted, which presented radiographically as the faint radiolu-

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Case Report—Clinical Techniques

Figure 1. Clinical photograph showing the red, smooth surfaced, sessile lesion with a slightly uneven surface on the maxillary facial attached gingiva apical to teeth #7 and #8 immediately before excision.

Figure 3. Hematoxylin and eosin stain (2.5⫻ magnification) exhibits stratified squamous epithelium overlying an odontogenic epithelial neoplastic process forming islands, cords, and cystic spaces.

cency seen apical to tooth #8. The specimen grossly measured 0.7 ⫻ 0.6 ⫻ 0.3 cm. It was fixed in 10% neutral buffered formalin and sent for histopathological examination.

The microscopic features were typical for a PA with variably sized islands and cords of odontogenic epithelial cells distributed in a fibrous stroma (Fig. 3) surfaced by keratinized stratified squamous epithelium. Larger odontogenic epithelial islands with areas of prominent cystic degeneration were seen throughout the fibrous connective tissue stroma. The neoplastic epithelial cells exhibited hyperchromatic nuclei and peripheral palisading with nuclei polarized away from the basal lamina (Fig. 4). The patient returned for follow-up 4 months later with no evidence of recurrence (Fig. 5). He has been placed on recall for annual follow-up.

Discussion The PA is a rare, benign, extraosseous odontogenic soft tissue tumor that was first reported in the literature by Kuru in 1911 (10). However, in this report the lesion proved to be an intraosseous ameloblastoma that had penetrated the alveolus and had presented peripherally (5). Stanley and Krogh reported the first, true peripheral ameloblastoma (PA) in 1959 (3). In a recent review, Philipsen et al. reported 160 cases of PAs documented in literature (5). They found that the age

Figure 2. Radiographic image showing a faint 0.75 ⫻ 2 cm periradicular welldefined radiolucency apical to tooth #8 and extending to the area between #7 and #8.

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Figure 4. Hematoxylin and eosin stain (63⫻ magnification) exhibits odontogenic epithelial cells exhibited hyperchromatic nuclei and peripheral palisading with nuclei polarized away from the basal lamina (reverse polarity).

Peripheral Ameloblastoma


Case Report—Clinical Techniques of these tumors into malignancies are rare, this cannot be overlooked (1, 8, 11). Periodic follow-up should be indefinite because of the possibility of recurrence, which has been reported to occur as late as 8 years after removal (4). This case highlights the need for treatment planning based on a comprehensive evaluation of all diagnostic modalities available including but not limited to radiographs, pulp testing, signs and symptoms, and microscopic examination of lesional tissue when necessary. Although rare, a PA must be considered by the endodontist in the differential diagnosis of gingival lesions especially those clinically simulating a parulis or gumboil. This case also highlights the importance of performing a biopsy and submitting tissue for microscopic examination even in cases where the clinical appearance of the lesion seems to indicate a lesion of routine inflammatory origin.

References Figure 5. Four-month follow-up showing no recurrence of the lesion.

range varied from 9 to 92 years with an average of 52 years. Mintz et al. and Manor et al. report that the most common sites of occurrence are the premolar or anterior regions of the mandible and this lesion clinically presents as a small, firm mass of the gingiva (2, 9). Differential diagnoses should include peripheral reactive lesions such as peripheral giant cell granuloma, peripheral odontogenic fibroma, peripheral ossifying fibroma, papilloma, pyogenic granuloma, epulis, and fibroma (4, 5). PAs have also been considered analogous to the so-called basal cell carcinoma of the gingiva (6). Malignant transformation of the PA is exceedingly rare (8, 11). In our case, the radiolucent bone alterations associated with a root canal treated tooth and the presence of a labial swelling led the referring clinician to consider residual inflammation arising from the previously treated tooth as the possible etiology. The asymptomatic nature of both the lesion and the associated tooth combined with the atypical appearance of the “parulis” (draining sinus tract) and the unusual radiographic evidence (cupping), all led to deferring possible endodontic retreatment. Instead, an excisional biopsy was opted as the prudent first step. The current treatment of choice for the PA is complete surgical excision (5). Although the possibility of recurrence and/or progression


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1. 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. 2. Mintz S, Anavi Y, Sabes WR. Peripheral ameloblastoma of the gingiva. A case report. J Periodontol 1990;61:649 –52. 3. Stanley HR Jr., Krogh HW. Peripheral ameloblastoma. Report of a case. Oral Surg Oral Med Oral Pathol 1959;12:760 –5. 4. Nauta JM, Panders AK, Schoots CJF, Vermey A, Roodenburg JLN. Peripheral ameloblastoma: a case report and review of the literature. J Oral Maxillofac Surg 1992;21:40 – 4. 5. Philipsen HP, Reichart PA, Nikai H, Takata T, Kudo Y. Peripheral ameloblastoma: biological profile based on 160 cases from the literature. Oral Oncol 2001;37:17–27. 6. Tajima Y, Kuroda-Kawasaki M, Ohno J, et al. Peripheral ameloblastoma with potentially malignant features: report of a case with special regard to its keratin profile. J Oral Pathol Med 2001;30:494 – 8. 7. Gardner DG. Some current concepts on the pathology of ameloblastomas. Oral Surg Oral Med Oral Pathol 1996;82:660 –9. 8. Baden E, Doyle JL, Petriella V. Malignant transformation of peripheral ameloblastoma. Oral Surg Oral Med Oral Pathol 1993;75:214 –9. 9. Manor Y, Mardinger O, Katz J, Taicher S, Hirshberg A. Peripheral odontogenic tumours-differential diagnosis in gingival lesions. Int J Oral Maxillofac Surg 2004;33:268 –73. 10. Kuru H. Ueber das admantinom. Centralbl f allg path u path anatomie (iena) 1911;22:291–5. 11. McClatchey EC, Sullivan MJ, Paugh DR. Peripheral ameloblastic carcinoma: a case report of a rare neoplasm. J Otolaryngol 1989;18:109 –11.

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