Peripheral ameloblastoma of the maxilla: a case report and literature review

Peripheral ameloblastoma of the maxilla: a case report and literature review

Available online at www.sciencedirect.com American Journal of Otolaryngology – Head and Neck Medicine and Surgery 29 (2008) 357 – 360 www.elsevier.co...

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Available online at www.sciencedirect.com

American Journal of Otolaryngology – Head and Neck Medicine and Surgery 29 (2008) 357 – 360 www.elsevier.com/locate/amjoto

Peripheral ameloblastoma of the maxilla: a case report and literature review Bryan J. Vanoven, DDS b , Noah P. Parker, BA a , Guy J. Petruzzelli, MD, PhD, MBA, FACS a,⁎ a

Department of Otolaryngology and Bronchoesophagology, Rush University Medical Center, Chicago, IL, USA b Department of Oral Surgery, Stroger Hospital of Cook County, Chicago, IL, USA Received 22 September 2007

Abstract

Peripheral ameloblastoma is a rare, benign, extraosseousneoplasm of the odontogenic epithelium. We report a case of peripheral ameloblastoma, detail our surgical therapy and review important elements in the pathological diagnosis and treatment of this unusual neoplams. © 2008 Elsevier Inc. All rights reserved.

1. Introduction Ameloblastoma is the most common neoplasm arising from odontogenic epithelium [1]. The tumor can be classified into 3 subgroups: intraosseous multicystic, intraosseous unicystic, and peripheral ameloblastoma (PA). Peripheral ameloblastoma is also referred to as extraosseous ameloblastoma because it arises outside the bone as opposed to the other subgroups. Multicystic and unicystic subgroups represent 86% and 13% of all ameloblastomas, respectively [2,3]. Peripheral ameloblastoma is a rarer subgroup, representing 1% of all ameloblastomas. As of 2001, a total of 160 cases of PA had been reported [4]. The report herein describes a patient who was found to have PA of the posterior maxilla. 2. Case report A 73-year-old man presented to his general dentist with a tender lesion on the left maxillary alveolus of unknown duration. He had been wearing an ill-fitting denture for years but had not reported prior lesions. He was subsequently referred to a head and neck surgeon for further evaluation. The patient reported no medical problems or prior surgeries but affirmed a cigarette smoking history of a half pack of ⁎ Corresponding author. Department of Otolaryngology-Head and Neck Surgery, Rush University Medical Center, 1725 West Harrison Street, Professional Building 1, Suite 218, Chicago, IL 60612, USA. Tel.: +1 312 942 6100. E-mail address: [email protected] (G.J. Petruzzelli). 0196-0709/$ – see front matter © 2008 Elsevier Inc. All rights reserved. doi:10.1016/j.amjoto.2007.10.002

cigarettes per day for 35 years before cessation nearly 10 years prior. He drank 1 to 2 alcoholic beverages 2 times per week. On examination, an ulcerating exophytic mass of about 3 cm was visualized on the left posterolateral maxillary alveolus of the edentulous patient (Fig. 1). The lesion did not extend buccally or medially but was tender on palpation. The remainder of the oral cavity and head and neck examination did not reveal lesions, masses, lymphadenopathy, or other abnormalities. Additional evaluation included biopsy under local anesthesia and imaging studies. Computed tomography studies of the facial skeleton revealed a complex cystic solid mass within the left maxillary alveolar ridge, causing bone destruction (Fig. 2). The lesion measured 3.6 × 2.4 cm and expanded into the maxillary sinus without significant bone destruction. There was also extension into the retromaxillary space and left nasal vault. The left middle and inferior turbinates appeared deformed and displaced medially against the nasal septum. The orbital floor was intact. The patient was scheduled for a partial maxillectomy with obturator reconstruction. 3. Surgical procedure and pathology The tumor was resected en bloc through a standard left lateral rhinotomy with lip split incision. The incision was made in the face, respecting the esthetic units of the nose, extending to, but not above, the medial canthal tendon on the left. The skin and subcutaneous tissues were incised and extended medially and laterally with a gingivobucccal sulcus incision to widely encompass the abnormal mucosa on the

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Fig. 1. Preoperative photograph at initial presentation of the tumor in situ. The mass is exophytic and\arising adjacent to the edentulous maxillar alveolar ridge.

alveolus. Osteotomies were made below the zygoma at the level of the inferior orbital nerve, across the alveolar process of the maxilla, and through the palate. The resection of the entire contents of the maxilla and the lateral nasal wall up to the level of the middle turbinate was performed. All gross tumor (Fig. 3), mucosa of the maxillary sinus, attenuated bone of the posterior maxilla, pterygoids, and suspicious tissue were meticulously removed and submitted for routine histopathologic examination. The osseous defect and cheek flap were lined with a split-thickness skin graft harvested from the anterior thigh. Bolster material was placed in the

Fig. 2. Preoperative coronal computed tomography scan. Note expansion of the alveolar process of the maxilla, medial bowing of the lateral nasal wall, the abscence of frank bone destruction and the intact orbital floor.

Fig. 3. Gross clinical photograph of bisected tumor specimen identifying large central cystic cavity.

maxillary sinus, and the patient's prior upper dental plate was lag screwed to the residual palate. Final pathology reports of the left maxillary ridge described a tumor consisting of a monotonous population of medium-sized cells forming nests with peripheral palisading, areas of squamous differentiation with keratin production, and abundant basement membrane production (Fig. 4). The final pathologic diagnosis was PA. 4. Discussion Garner [5] reported a maximum incidence of PA between the fifth and sixth decades of life. The average age at presentation is 50 years old, and a slight male predominance has been observed. The multicystic and unicystic variants of ameloblastoma, often termed intraosseous ameloblastoma

Fig. 4. Histopathology of primary tumor. Palisading epithelium with focal squamous differentiation and keratin production. (Hematoxylin and Eosin 20 X).

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(IA) occur most commonly between the second and third decades of life. The average age at presentation of IA is 50 years old. Peripheral ameloblastoma is thought to arise from either extraosseous remnants of dental lamina or the basal cell layer of surface epithelium [6] and is typically found in the retromolar aspect of the mandible. Other less common regions include the maxilla, where the posterior tuberosity is the most common site, the buccal mucosa, or the floor of the mouth. Peripheral ameloblastoma typically presents as a slow, painless, exophytic growth of the gingival or oral mucosa [7], although 6 cases of PA in extragingival locations have been reported [8]. Of note, the rarer extragingival form may originate from odontogenic remnants of dental lamina or cells in the basal cell layer of the surface epithelium as well, but the origin from stratified squamous epithelium or pluripotent cells of minor salivary glands has also been proposed [9,10]. The tumor itself can be visualized as a 1- to 2-cm sessile, broad, or pedunculated mass [11] with a granular, pebbly, papillary, or warty surface [12]. Lesions can range from pink in color identical to the normal mucosa to dark red. Patients are usually dentulous, and tooth separation can occur if the lesion is located in the interdental papilla. The differential diagnosis for such presentations includes peripheral giant cell granuloma, pyogenic granuloma, peripheral ossifying fibroma, papilloma, and epulis [13], as well as basal cell carcinoma (BCC). Ill-fitting dentures can also add to the differential, which is relevant to our patient. The irritation can cause the development of lesions such as epulis fissuratum and inflammatory papillary hyperplasia [2] that can become further traumatized during mastication. Differentiating between these lesions can be aided by radiography and tissue biopsy. Peripheral ameloblastoma is a benign tumor and is radiographically shown to be superficial to cortical bone without signs of bone involvement. The tumor's lack of penetration may be due to a barrier created by fibrous tissue of the gingiva and periosteum [5]. A few cases have shown some bone involvement, which was referred to as cupping or saucerization. This process refers to a depression made from the pressure of the tumor on bone; however, saucerization is usually mild, and no neoplastic invasion or marrow infiltration is typically seen [14-16]. For this reason, PA is considered less aggressive than IA, which does invade bones. Histologic features of PA reveal ameloblastic growth under an intact layer of overlying squamous epithelium. The ameloblastic growth transitions to tumor composed of islands, consisting of a central mass of loosely connected stellate reticulum-like cells [12]. The most common histomorphological cell pattern types are plexiform or follicular. The pathology in our case is consistent with these findings. The 2 subgroups of IA, multicystic and unicystic, are further classified based on the degree of differentiation of the epithelium and the amount of matrix production. The

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multicystic subgroup can be further divided into plexiform, acanthomatous, follicular, granular cell, desmoplastic, and basaloid subgroups by histology. The unicystic subgroup is further classified by the tumor's relationship with the luminal surface, which includes luminal and intraluminal. Peripheral ameloblastoma is diagnosed by the presence of the tumor located external to the bone [17]. An interesting aspect of the histology of PA is that it shares many of the features as BCC, which can present similarly. In fact, the 2 lesions have been proposed as being the same entity [18]. Both are characterized by a proliferation of basal cells often arranged in nests and intermixed with a fibrous stroma. However, PA can be differentiated by nuclei located on the upper part of the cytoplasm, whereas BCC has nuclei located on the base of the cytoplasm. In addition, immunohistochemical analysis has been used to distinguish the 2 tumors. Peripheral ameloblastoma is positive for cytokeratin 19 and negative for Ber-EP4, whereas the opposite is true for BCC [19,20]. It is important to distinguish between the 2 because it affects treatment. Because PA is benign, it is treated by local excision, whereas BCC requires a much larger resection. Although PA is considered a benign tumor, one report of 6 cases of a malignant variety exists. In these cases, malignant transformation was supported by diffuse invasion, aggressive growth, and destructive recurrence [21]. Another report of malignant PA with metastasis posited that the malignant form arises either de novo or as a dedifferentiated carcinoma from a preexisting benign PA [22]. The malignant form can be further classified as 2 subtypes. The first consists of primary and metastatic lesions consisting of well-differentiated benign-appearing PA. The second consists of a primary lesion demonstrating dedifferentiation with or without metastasis [21]. Treatment of PA consists of surgical excision down through the periosteum. Recurrence is rare even with conservative resection; however, recurrence and progression to malignancy of residual disease can occur. Therefore, longterm follow-up is essential [23]. Acknowledgment Thanks to Paulo Gattuso, MD, and Sejal Patel, MD, from the Department of Pathology at Rush University Medical Center, Chicago, IL, for their expertise in pathologic and histologic diagnosis. References [1] Hollows P, Fasanmade A, Hayter JP. Ameloblastoma—a diagnostic problem. Br Dent J 1999;188:1-3. [2] Waldron CA. Odontogenic cysts and tumors. In: Neville BW, Damm DD, Allen CM, et al, editors. Oral and maxillofacial pathology. 2nd ed. Philadelphia (PA): WB Saunders; 2002. p. 511-20. [3] Sapp JP, Eversole LR, Wysocki GP, editors. Contemporary oral and maxillofacial pathology. 2nd ed. St Louis (MO): Mosby; 2004. p. 136-43.

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