International Journal of Morphology
versión On-line ISSN 0717-9502
Int. J. Morphol. v.26 n.2 Temuco jun. 2008
Int. J. Morphol., 26(2):263-268, 2008.
Desmoplasic Ameloblastoma in Maxilla - Report of Case and Review of the Literature
Ameloblastoma Desmoplásico en la Maxila - Relato de un Caso y Revisión de la Literatura
*Pollianna Muniz Alves; *Karuza Maria Alves Pereira; *Marcelo Gadelha Vasconcelos; **Lélia Batista de Souza; **Lélia Maria Guedes de Queiroz & **Ana Myriam Costa Medeiros
* DDS, MSc, Department of Oral Pathology, School of Dentistry, Federal University of Rio Grande do Norte, Natal, RN, Brazil.
SUMMARY: The ameloblastoma is a benign neoplasm of epithelial odontogenic origin, slowly growing, locally invasive and it is the most common odontogenic tumor in the jaws. Histologically, various types have been described in literature. The desmoplastic variant is rare and characterized by difference in the typical findings of ameloblastoma, including localization, radiographic and histological features. The purpose of this article is to report a case of desmoplastic ameloblastoma in the left maxilla, and review of relevant literature, emphasizing peculiar aspects of this unusual lesion.
KEY WORDS: Ameloblastoma; Desmoplastic Ameloblastoma; Odontogenic tumours.
RESUMEN: El ameloblastoma es una neoplasia benigna de origen epitelial odontogénica de crecimiento lento, localmente invasiva y constituye el tumor odontogénico más común en los maxilares. Histológicamente, existen varios tipos descritos en la literatura. La variante desmoplástica es rara y se caracteriza por diferencias en los hallazgos típicos del ameloblastoma, incluso la localización y aspectos radiográficos e histológicos. Los objetivos de este artículo son relatar un caso de ameloblastoma desmoplásico en el lado izquierdo del maxilar superior y presentar una revisión de la literatura relevante, enfatizando aspectos peculiares de esta rara lesión.
PALABRAS CLAVE: Ameloblastoma; Ameloblastoma desmoplásico; Tumores odontogénicos.
The ameloblastoma is a benign odontogenic tumor of epithelial origin that exhibits a locally aggressive behavior with a high level of recurrence, being believed to theoretically come from dental lamina remains, the enamel organ in development, epithelial cover of odontogenic cysts or from the cells of the basal layer of the oral mucosa (Güngüm & Hos.goren, 2005; Adebiyi et al, 2006).
The ameloblastoma is the second most common odontogenic tumor of epithelial origin (25%) that happens in the oral cavity, often attacking the molar regions and ascending ramus of the mandible (Fregnani et al, 2007), and only about 20% happens in the posterior maxilla región. The lesión presents prevalence between the third and the fourth life decade, equally affecting both genders and having no predilection for race (Zwahlen & Grantz, 2002; Ledesma-Montes et al, 2007). The tumor is usually asymptomatic, grows slowly and small lesions can be detected only by routine radiographic exams. The lesión can cause increase in volume, pain, bad occlusion and paresthesia of the affected área (Becelli et al, 2002). Radiographically, the neoplasia can be presented as a unilocular or multilocular radiolucent image in the shape of "soap bubbles" or "honeycomb". The re-absorption of the adjacent teeth roots is not found to be uncommon and the presence of a tooth inside, usually the inferior third molar, can be associated to the tumoral mass (Hollows et al, 2000; Neville et al, 2004).
Various histological patterns of the ameloblastoma are described on the literature, including the follicular, plexiform and acantomatosous types, of granular cells, basal cells and the desmoplasic (Dos Santos et al, 2006). Recently, the World Health Organization (WHO) considered the desmoplasic ameloblastoma not only a histological variant, but a clinic variant of this tumor itself.
The desmoplasic ameloblastoma is a rare variant, initially described in 1984 by Eversole et al. (Hirota et al, 2005; Desai et al., 2006), which presents accentuated predilection for the anterior región of the maxilla and the mandible, preferably for the maxilla (Neville et al.). The tumor usually happens between the third and fifth life decade, with an equal attack rate between men and women. It represents from 4 to 5% of all ameloblastomas (Manuel et al, 2002). In relation to the radiographic aspects, this type of lesión rarely suggests the diagnosis of an ameloblastoma and, many times, it is similar to a fibro-osseous lesión due to its mixed radiopaque-radiolucent appearance of loóse outline (Iida et al, 2002; Kaffe et al, 1993). Histologically, the desmoplasic ameloblastoma is characterized by a stroma with intense desmoplasia, densely collagenized, comprising little odontogenic epithelium islands and cords of various sizes (Iida et al; Manuel et al; Dos Santos et al).
This article aims to report a case on a desmoplasic ameloblastoma of rare location, emphasizing the clinic and histopathological aspects that are relevant for the diagnosis and treatment of this pathology.
Female patient, 45 years old, white, looked for odontological assistance complaining about a lesión in the left maxilla, in the región that corresponds to the molar one. It has had for 5 years. Through the intra-oral exam, it was observed a tumoral lesión, ulcerated, symptomatic, pinkish-reddish coloration, irregular surface of imprecise outlines, firm consistency, exophytic, sessile implantation and measuring on its biggest diameter 2.5 cm (Fig. 1). Through the ectoscopic exam, there could be seen a volumetric increase of the left side of the face, causing facial asymmetry, involving the ocular globe as well. The patient also complained about nasal obstruction and lachrymation. The occlusal and panoramic radiographies showed the presence of a radiolucent image of irregular edges, with discreet radiopaque focus in its interior (Figs. 2 and 3). Because of this, an incisional biopsy was done and the fragment removed was taken to the Servigo de Anatomia Patológica da Disciplina de Patologia Oral da Faculdade de Odontología -UFRN. The incisional biopsy reveled fragments of a benign neoplasia of odontogenic origin, characterized by the proliferation of small odontogenic epithelium islands and cords interlarded by a dense fibrous stroma, exhibiting intense collagenized áreas (Fig. 4). It can also be seen in some of these islands the presence of squamous metaplasia, peripheral cells arranged in palisade exhibiting hyperchromatism and cores of reverse polarity. In the center of the islands, loosely organized cells were found, resembling the stellate reticulum of the enamel organ (Fig. 5). From these findings, a histopathological diagnosis was issued as of being a desmoplasic ameloblastoma. Then, the patient was sent to surgical treatment in order to have the lesión totally removed. The patient was kept for follow up for 18 months, with no signs of recurrence.
The desmoplasic ameloblastoma was firstly describedby Eversole et al. (1984), who described three cases (Hirota et al.) It is a rare entity that exhibits important differences in its anatomical, histological and radiographic distribution when compared to other kinds of ameloblastoma. Thus, by presenting its own clinic and radiographic characteristics, the desmoplasic ameloblastoma has been considered by some authors as a distinct clinic-pathological entity. This was recently confirmed by the World Health Organization, in 2005, whose classification organized the ameloblastomas in solid, extra-osseous, desmoplasic and unicystic (Phillipsen et al., 1992; Dos Santos et al.).
The literature shows the desmoplasic ameloblastoma as the least frequent odontogenic tumor. Among 89 ameloblastoma cases studied by Takata et a/.(1999), seven (7.9%) were diagnosed as desmoplasic, and in another study of 163 ameloblastoma cases done by Ledesma-Montes et al. in the Latin American región, two were desmoplasic. According to Adebiyi et al., from 77 cases of ameloblastomas diagnosed within the Nigerian population, four were the cases diagnosed as desmoplasic.
More than 70% of the desmoplasic ameloblastoma cases happen in the anterior región of the maxilla (Kaffe et al, Manuel et al.), the opposite from the conventional ameloblastomas, which are usually found in the posterior región of the mandible. In 15 cases of desmoplasic ameloblastoma analyzed by Kaffe et al., 11 lesions were located in the maxilla (73%) and only four in the mandible (27%), with most of the cases reaching the anterior región. These findings partially corrobórate with the clinical case presented here, since the lesión was located in the posterior región of the maxilla. However, in another study of ten desmoplasic ameloblastoma cases reported by Kishino et al. (2001), 40% involved the anterior región of the maxilla and 60%, the posterior región of the mandible. On a literature review done by Desai et al, from the 89 cases studied, the desmoplasic ameloblastoma's occurrence predilection is in the anterior región of the jaw bones, being the mandible the most common one (57.3%) when compared to the maxilla (42.7%).
The clinical aspects presented in this case are in agreement to the characteristic reports presented on the literature, with a proportional attack happening between men and women, specially within the third and fifth life decade (Manuel et al.). To Kaffe et al, the lesions usually attack the female gender most in a 2:1 proportion. However, in the 89 cases reviewed by Desai et al. ,54.66% involved the male gender and 45.33% the female one. Frequently, the tumor is asymptomatic, the tumefaction is painless or the maxüla expansión are commonly observed clinical manifestations (Neville et al.) In the case reported here, the patient had a painful symptomatology and áreas of ulceration, probably because of the size of the lesión (Becelli et al.) and the trauma during mastication.
The radiographic findings, observed in the case mentioned above, are typical on the desmoplasic ameloblastoma, presenting itself as a unilocular radiolucent lesión of indefinite outlines. Discreet radiopaque focuses could be observed inside the lesión through an occlusal and panoramic radiography, characteristic observed in more than 50% of the cases, imitating many times a fibro-osseous lesión due to its radiolucent-radiopaque mixed appearance (Kawai et al, 1999). The differential diagnosis according to the radiographic aspects include fiber-osseous lesions, fiber dysplasia, chronic osteomyelitis and ossifying fibroma (Iida et al.)
The histopathological characteristics described for this case are in accordance to the diagnosis criteria established for the desmoplasic ameloblastoma according to Kishino et al. This way, such lesión is characterized by small nests and cords of odontogenic tumoral epithelium, organized in an abundant stroma densely collagenized, which makes these tumoral islands seem like they are comprised (Dos Santos et al., Hirota et al.) The peripheral cells can lose, sometimes, those morphologic characteristics similar to the ameloblastomas such as the polarity inversión. In addition to this, the central portion of the tumoral islands can present loosely organized cells resembling the stellate reticulumof the enamel organ, with occasional squamous metaplasia and central focuses of keratination (Takata et al.) In the desmoplasic variation, usually, there can be verified an osseous neo-formation that according to Thompson et a/.(1996), represents an attempt to fix the damages caused by the osseous re-absorption caused by the tumoral expansión. In the case above, such osseous formations were not evidenced in the epithelial proliferation.
The most important characteristic of the desmoplasic ameloblastoma is the extensive collagenization present in the stroma of the lesión, also called desmoplasia. It has been proposed that this phenomenon has its origin from a new protein synthesis that comes from the extracellular matrix where such components play a fundamental role in supporting, adhering, proliferating, migrating and differing tumoral cells, interfering in the behavior and modulation of the tumoral cells (Desai et al.; Phillipsen et al, 2001).
According to Philippsen et al. (1992), radiographically, the badly-defined lesión borders suggest an infiltrated process that tends to be recurrent. The significant stromal reaction can be seen as a reply from the host trying to make the lesión stop growing. The recurrence level of the desmoplasic variant is still not known due to the low number of reported cases in the literature. However, similar recurrence has been seen with other types of ameloblastomas. Due to the lack of capsule and precise limits, a radical treatment is recommended for most of the cases (Ashman et al, 1993) However, because of the limitedunderstanding on the biological and prognostic behavior, the therapeutical approach strategy is still not completely clear.
The desmoplasic ameloblastoma is a rare entity that presents a radiographic appearance that resembles a fibro-osseous lesión that needs a diagnosis based not only on clinical and radiographic aspects, but also on those histopathological ones. However, the importance of knowing the ameloblastomas' histological and radiographic variants in relation to possible differential diagnosis and prognosis to confirm and, consequently, apply proper therapy is highlighted.
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Received: 12-12-2007 Accpeted: 26-02-2008