|Year : 2020 | Volume
| Issue : 1 | Page : 81-85
Desmoplastic ameloblastoma of the mandible: A rare case report
Prachi M Desai, Manisha Khorate, Nigel Figueiredo
Department of Oral Medicine and Radiology, Goa Dental College and Hospital, Bambolim, Goa, India
|Date of Submission||18-Sep-2019|
|Date of Decision||20-Dec-2019|
|Date of Acceptance||28-Feb-2020|
|Date of Web Publication||17-Apr-2020|
Dr. Prachi M Desai
Department of Oral Medicine and Radiology, Goa Dental College and Hospital, Bambolim - 403 202, Goa
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Desmoplastic ameloblastoma (DA) is a rare variant of ameloblastoma that shows unique features, behavior, and presentation. This article reports a rare case of desmoplastic ameloblastoma in a 67-year-old male patient, who presented with a slow-growing, asymptomatic lesion in the anterior mandible which was observed over a period of 4 years. Radiographic findings revealed an ill-defined mixed radiolucent and radiopaque lesion with displacement of adjacent teeth. Histopathological examination showed proliferation of odontogenic cells in the form of islands separated by dense, fibrous connective tissue stroma compressing the islands. Although the incidence of this variant is very low, a differential diagnosis of the same must be taken into consideration when locally aggressive, chronic swellings of jaw are encountered in routine practice to aid in early diagnosis and in initiating a prompt management.
Keywords: Desmoplastic ameloblastoma, granular cell change, odontogenic tumor, stromal desmoplasia
|How to cite this article:|
Desai PM, Khorate M, Figueiredo N. Desmoplastic ameloblastoma of the mandible: A rare case report. J Indian Acad Oral Med Radiol 2020;32:81-5
|How to cite this URL:|
Desai PM, Khorate M, Figueiredo N. Desmoplastic ameloblastoma of the mandible: A rare case report. J Indian Acad Oral Med Radiol [serial online] 2020 [cited 2020 May 30];32:81-5. Available from: http://www.jiaomr.in/text.asp?2020/32/1/81/282606
| Introduction|| |
Odontogenic neoplasms are a heterogeneous group of lesions having diverse clinical behavior and histopathologic types, ranging from hamartomatous lesions to malignancy. Ameloblastoma is the second most common odontogenic neoplasm. It manifests as a locally invasive, destructive, and aggressive lesion. Desmoplastic ameloblastoma constitutes 0.9% to 12.1% of all ameloblastomas. The mean age at initial presentation is 42.3 years (range 17–70 years) with age and gender predilection similar to that of other ameloblastomas. It has a predilection for occurrence in the anterior regions of the maxilla and mandible. It appears as a mixed radiolucent radiopaque lesion, which resembles a benign fibro-osseous lesion. This unusual variant is characterized histologically by extensive stromal collagenization or desmoplasia with small nests and strands of odontogenic epithelium.
This case report describes a rare case of Desmoplastic Ameloblastoma with unusual findings in a 67-year-old male patient.
| Case History|| |
A 67-year-old male patient was referred by a private practitioner to the out-patient department in view of a swelling over the left side of the lower jaw. The patient claimed that the swelling was present for 4 years and also informed that it was initially small in size (grape-sized) and had gradually increased to its present size. There was no associated pain, paraesthesia, bleeding, or pus discharge from the region. The patient gave a history of exfoliation of one tooth in the same region 10 years back due to mobility. The patient did not notice any swelling in the region at that time. The patient gave a history of chewing betel quid containing betel nut, tobacco, and slaked lime six to seven times a day for the last 55 years.
On extraoral examination, a diffuse swelling was seen over the left parasymphysis region of the mandible [Figure 1]. The overlying skin was smooth and mildly tense with no evidence of any discharge. On palpation, the swelling was firm in consistency, nontender, nonpulsatile, and noncompressible, with no local rise in temperature. There was no lymphadenopathy. Intraoral examination revealed a spherical swelling measuring approximately 3.5 × 3 cm in the left mandibular labial and buccal vestibule, extending from 31 till the 35 region mesiodistally, and from the marginal gingiva of the involved teeth till the vestibular depth [Figure 2]. The surface was smooth, shiny, with the mucosa appearing stretched with no evidence of ulceration. An indentation of the opposing canine (23) was seen over the superior aspect of the swelling. Buccal cortical expansion of the alveolus, which was smooth on palpation, was noted without lingual expansion. On palpation, the swelling was bony hard in consistency, nontender, nonpulsatile, nonreducible, nonfluctuant, and noncompressible. On examination of the teeth, 32 and 33 were missing and 34 was displaced distally. No tenderness or mobility of the teeth in the area was noted. Based on the clinical features, a provisional diagnosis of an odontogenic cyst with a differential diagnosis of Odontogenic Tumor and Fibro osseous lesion was considered.
|Figure 1: Extraoral view showing diffuse swelling over left parasymphysis region of the mandible|
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|Figure 2: Intraoral view showing swelling involving the left mandibular labial and buccal vestibule|
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On radiographic examination, a series of intraoral periapical radiographs showed a mixed radiolucent and radiopaque lesion with an ill-defined border extending from the mesial aspect of 31 up to the distal aspect of 35 mesiodistally, and from the alveolar crest to 1 cm superior to the inferior border of the mandible, superoinferiorly [Figure 3]. A mandibular true occlusal view showed a mixed radiolucent and radiopaque lesion in 31 to 35 region causing buccal cortical expansion with the destruction of the cortex [Figure 4]. A panoramic radiograph showed an ill-defined, circular mixed radiolucent and radiopaque lesion extending from the mesial aspect of 31 up to distal aspect of 35, superiorly involving the alveolar crest and inferiorly extending approximately 1 cm superior to the inferior border of the mandible. The internal structure was mixed with sparse trabeculation. There was evidence of displacement of 33 inferomedially, crossing the midline with distal displacement of 34 and 35 without any evidence of root resorption [Figure 5]. Computed tomography revealed a lytic expansile lesion with a mesh of radiopaque structures with ill-defined borders causing destruction of the buccal cortex [Figure 6]a, [Figure 6]b, [Figure 6]c. 3D reconstructed computed tomography picture showed an expansile lesion causing destruction of bone with few irregular internal trabeculae [Figure 7].
|Figure 3: Intraoral Periapical radiograph showing mixed radiolucent and radiopaque lesion|
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|Figure 4: Mandibular true occlusal radiograph showing buccal cortical expansion with destruction of the cortex|
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|Figure 5: Orthopantomogram showing an ill-defined, circular mixed radiolucent and radiopaque lesion extending from the mesial aspect of 31 up to distal aspect of 35 with mesially displaced 33 crossing the mid-line|
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|Figure 6: (a, b, c): Lytic expansile lesion with a mesh of radiopaque structures with ill-defined borders causing destruction of the buccal cortex|
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|Figure 7: (a, b): Expansile lesion causing destruction of bone with a few irregular internal trabeculae|
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Based on these findings, a radiographic diagnosis of Adenomatoid Odontogenic Tumor was made, with a differential diagnosis of Desmoplastic Ameloblastoma, Ossifying Fibroma, and Calcifying Epithelial Odontogenic Tumor [Table 1].
An incisional biopsy of the lesion was performed and the histopathological examination showed proliferation of odontogenic cells in the form of rosettes, islands, nests, and sheets separated by dense fibrous connective tissue stroma compressing the islands. Few islands showed a single layer of cuboidal cells with a palisaded nucleus toward the periphery. The cells showed granular cytoplasm with centrally placed vesicular nuclei. Areas of hyalinization and cystic degeneration were evident [Figure 8]. Thus, based on the clinical, radiographic, and histopathologic features, a final diagnosis of Desmoplastic Ameloblastoma with granular cell change was made. Aspiration was not attempted in our case.
|Figure 8: (a-10×; b-40×): H and E stained section showing compressed ameloblastic islands separated by dense, hyalinized, fibrous connective tissue stroma|
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Further, the patient was planned for partial mandibulectomy and reconstruction with an iliac bone graft. However, he refused to give a consent to undergo surgery despite being explained the chances of further progression of the lesion and was subsequently lost to follow-up.
| Discussion|| |
Desmoplastic Ameloblastoma has been characterized by the WHO as a variant of ameloblastoma with specific clinical, radiographic imaging, and histological features. The first detailed report on the desmoplastic variant of ameloblastoma in English literature was given by Eversole et al., in 1984, who called it an ameloblastoma with pronounced desmoplasia. However, Nagalakshmi.V et al. were the early ones to draw attention to this unusual variant, characterized by extensive stromal desmoplasia with small compressed nests and strands of odontogenic epithelium.
Desmoplastic Ameloblastoma from different geographical regions seem to suggest a biogeographical pattern in that the relative frequency of desmoplastic ameloblastoma is slightly higher in the Asian population. However, more systematic studies on desmoplastic ameloblastoma are needed to prove such suggestions.
Regarding its origin, it is suggested that desmoplastic ameloblastoma develops from the periodontal membrane of the related tooth. Moreover, some suggest that desmoplastic ameloblastoma might arise from epithelial rests of Malassez in the periodontal membrane. In the present case, the disappearance of the lamina dura and the periodontal ligament space of the adjacent lateral incisor root was clearly identified.
Clinically, Desmoplastic Ameloblastoma may develop at any age; however, people in the 4th and 5th decade are more prone to be affected. No gender predilection of Desmoplastic Ameloblastoma has been reported. Approximately half of the desmoplastic lesions are located in the maxilla, and the vast majority of them occur in the anterior or premolar portion of the jaws. This is in contrast to the location of the unicystic or classic types of ameloblastoma, which usually are found in the posterior area of the mandible. Anand et al. (2017) reviewed approximately 238 cases of Desmoplastic Ameloblastoma and found a mean age of 41.11 ± 13.46 years, ranging between 13 and 83 years. A slight male predilection (51.76%) was observed with the mandible being more involved (52.55%) than the maxilla. Anterior region was more commonly involved in both the jaws.
The main symptom at first clinical examination of Desmoplastic Ameloblastoma is a painless swelling, with frequent buccal expansion. The present case showed similar clinical findings as reported in the literature. The present case was diagnosed in a 67-year-old male with occurrence in the anterior mandible.
Radiographically, most cases of desmoplastic ameloblastoma present with poorly demarcated borders. According to Philipsen et al., radiographically ill-defined borders suggest an infiltrative process with propensity to recur. The internal structure usually appears mixed (radiolucent and radiopaque lesion) sometimes mimicking a benign fibro-osseous lesion. Three radiographic presentations of Desmoplastic Ameloblastoma have been identified as follows: Type I-Both radiolucent and radiopaque appearance (Osteofibrosis type); Type II-Completely radiolucent appearance (Radiolucent type); and Type III-Both radiolucent and radiopaque appearance combined with a large radiolucent change (Compound type). The osteofibrosis type (14 cases reported in the literature) is the most common pattern and was also seen in the present case. The compound type is the least common and only 3 cases have been reported till date. The mixed radiographic appearance is due to osseous metaplasia within the dense fibrous septae that characterize the lesion, and not because of the production of a mineralized product by the tumor. In the review of literature by Anand et al. (2017), most of the lesions presented with a multilocular appearance (50%) with ill-defined borders (65.78%), exhibiting a mixed radiopaque-radiolucent appearance (62%).
Tooth displacement is a common feature in almost 92% of the cases and root resorption is seen in around 33% of cases. The radiographic findings in the present case showed no root resorption. However, displacement of the adjacent teeth was noted and the tumor was also associated with a missing tooth.
In all the reported cases of desmoplastic ameloblastomas, typical radiographic features of conventional ameloblastoma were not observed. The present case, too, lacked typical findings of ameloblastoma. The mixed internal structure was more in favor of a fibro-osseous lesion or ossifying fibroma.
The following histopathological features are usually observed during microscopic examination of Desmoplastic Ameloblastoma: 1) Stromal desmoplasia, in the form of moderately cellular, fibrous connective tissue with abundant collagen, which is the most consistent and distinguishing feature; 2) Islands of different shapes in the epithelial component; 3) Peripheral layer of cuboidal cells; and 4) Hypercellular central area composed of spindle-shaped or polygonal epithelial cells. Areas of hyalinization and cystic degeneration were also seen in our case.
It exhibits a more aggressive behavior than other types of ameloblastoma. This aggressiveness may be due to 1) potential to grow to a large size; 2) the common location in the maxilla leading to an early invasion of adjacent structures; 3) the diffuse radiographic appearance; and 4) histologic finding of bone invasion. In the present case, the exact initiation of the lesion is not known but as per the patient's history, the lesion appeared to be slow growing over a period of 4 years.
Philipsen et al. suggested that desmoplastic ameloblastomas in the maxilla would be more aggressive than those in the mandible. Mendenhall et al. also suggested that maxillary ameloblastomas tend to have a higher local recurrence rate because of the thinness of the cortical bone, which was a less effective barrier to tumor invasion compared with the mandible. Consequently, maxillary ameloblastomas may have a tendency to spread earlier and more quickly than do mandibular neoplasms.
Resection is the most preferred treatment option for desmoplastic ameloblastoma although some cases have been treated by enucleation and/or curettage. However, curettage leaves islands of tumor within bone, which later manifest as recurrences. Keszler et al. reported a higher recurrence rate (21.4%) for desmoplastic variant than the other types (10.1%) of ameloblastoma. Therefore, block excision is the most widely used treatment to avoid recurrence.
The desmoplastic ameloblastoma is in itself a rare entity. Its progression to squamous cell carcinoma is very rare. Rais and El-Mofty reported a case of Desmoplastic Ameloblastoma with malignant transformation to Squamous Cell Carcinoma in a 49-year old African American man. However, owing to its aggressive nature, a long-term follow-up is important to monitor for any signs of recurrence.
| Conclusion|| |
Desmoplastic Ameloblastoma is a rare variant which presents with specific clinical, imaging, and histological features. There is a need to create an awareness among the clinicians regarding this unusual presentation. A differential diagnosis of Desmoplastic Ameloblastoma should be considered in case of a swelling presenting in the anterior region of the jaws, especially those lesions showing a mixed radiolucent-radiopaque internal structure. Owing to its increased growth potential and propensity for recurrence, an accurate diagnosis and surgical management along with a regular follow-up are mandatory.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given his consent for his images and other clinical information to be reported in the journal. The patient understands that his names and initials will not be published and due efforts will be made to conceal identity, but anonymity cannot be guaranteed.
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Conflicts of interest
There are no conflicts of interest.
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