Ameloblastic carcinoma masquerading as dentigerous cyst of the mandible

Sruthi Selvam; Subramaniyan Damodaran; Venkatapathy Ramesh; Jonathan M Daniel

doi:10.4103/jorr.jorr_11_19

CASE REPORT

Year : 2019 | Volume : 11 | Issue : 2 | Page : 81-84

Ameloblastic carcinoma masquerading as dentigerous cyst of the mandible

Sruthi Selvam¹, Subramaniyan Damodaran², Venkatapathy Ramesh², Jonathan M Daniel¹
¹ Department of Oral Medicine and Radiology, Mahatma Gandhi Postgraduate Institute of Dental Sciences, Puducherry, India
² Department of Oral Pathology and Microbiology, Mahatma Gandhi Postgraduate Institute of Dental Sciences, Puducherry, India

Date of Submission	19-Mar-2019
Date of Acceptance	27-May-2019
Date of Web Publication	15-Jul-2019

Correspondence Address:
Sruthi Selvam
Department of Oral Medicine and Radiology, Mahatma Gandhi Postgraduate Institute of Dental Sciences, Gorimedu, Puducherry
India

Source of Support: None, Conflict of Interest: None

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DOI: 10.4103/jorr.jorr_11_19

Abstract

Ameloblastic carcinoma (AC) is a rare primary odontogenic tumor that has histological features of both ameloblastoma and carcinoma. The term AC was introduced by Elzay. In the last update of the World Health Organization classification, published in 2005, AC is defined as a rare odontogenic malignancy that combines the histological features of ameloblastoma with cytological atypia, even in the absence of metastases. It may develop de novo (primary type) or by malignant transformation of an ameloblastoma (secondary type) with a distinction between carcinoma ex intraosseous ameloblastoma and carcinoma ex peripheral ameloblastoma. Malignant ameloblastomas represent tumors that metastasize while both primary and metastatic lesions retain their benign histological appearance. We report a case of AC of the mandible in a 32-year-old male patient with clinical and radiological images and pathological features.

Keywords: Ameloblastic carcinoma, mandible, primary tumor, young male

How to cite this article:
Selvam S, Damodaran S, Ramesh V, Daniel JM. Ameloblastic carcinoma masquerading as dentigerous cyst of the mandible. J Oral Res Rev 2019;11:81-4

How to cite this URL:
Selvam S, Damodaran S, Ramesh V, Daniel JM. Ameloblastic carcinoma masquerading as dentigerous cyst of the mandible. J Oral Res Rev [serial online] 2019 [cited 2020 Nov 25];11:81-4. Available from: https://www.jorr.org/text.asp?2019/11/2/81/262759

Introduction

In 1982, Elzay suggested that the World Health Organization (WHO) classification of odontogenic carcinoma (1972) be modified to separate ameloblastic carcinoma (AC) from a malignant ameloblastoma, because the latter retains benign histologic features in both primary and metastatic lesions.^[1] In 1984, Slootweg and Müller suggested a slight modification of Elzay's classification regarding the origin of the tumor. After considerable debate, the latest update of the WHO classification of odontogenic tumors was published in 2005.^[2] Most ACs appear to arise de novo, but a few cases arising from a preexisting ameloblastoma have been reported. Because of the rarity of well-documented cases, there is no reliable evidence of the clinical behavior of AC, and for that reason, no definite recommendation for treatment is available. This case report describes the clinical, radiological, and histopathological features of a 32-year-old young male patient diagnosed with AC with no metastasis to the regional lymph nodes.

Case Report

A 32-year-old male patient reported to the department of oral medicine and radiology with the chief complaints of pain and swelling in the left side of the lower jaw for the past 2 months. The patient was apparently normal 2 months before and then he experienced pain in the left side of the lower jaw, which was dull, intermittent in nature, and aggravated on jaw movement, and there was no history of radiating pain. Subsequently, he had swelling in the same region for the past 1 month, which was initially smaller in size, accompanied by occasional salty fluid discharge from the swelling. Initially, mouth opening was mildly restricted and then slowly progressed to present state, i.e., 11 mm. There was no history of trauma, numbness/paresthesia.

Medical history, family history, and personal history of the patient were found to be noncontributory. Extraoral examination revealed facial asymmetry with diffuse swelling on the left side of the preauricular region of size 5 cm × 4 cm, which extends anteriorly 1 cm away from the left corner of the mouth, posteriorly to the posterior border of the mandible, superiorly at the level of the left outer canthus of the eye, and inferiorly to the angle and body of the mandible [Figure 1]a. The surface of the swelling showed no secondary changes such as sinus opening or pus discharge. On palpation, inspection findings were confirmed with no local rise in surface temperature. Swelling was tender, soft to firm in consistency, nonpulsatile, noncompressible, nonreducible, and nonfluctuant. Mouth opening was 11 mm with restricted lateral and protrusive jaw movements. On temporomandibular joint (TMJ) examination, tenderness was elicited on the left side of the preauricular and masseter muscle, and the TMJ movements were nonpalpable on the left side of the preauricular. On lymph node examination, there were two enlarged submandibular lymph nodes on the left side measuring 0.5 cm × 0.5 cm, which were tender, soft in consistency, and mobile.

Figure 1: (a) Extraoral profile showing mild facial asymmetry with diffuse swelling in the left side of the face. (b) Intraoral view showing restricted mouth opening. (c) Resected specimen extending from 37 to condylar and coronoid process

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On intraoral examination, mouth opening was 11 mm. Diffuse swelling was present distal to tooth 37, which extended inferiorly to buccal vestibule. Posterior, superior, and lingual extension cannot be assessed due to restricted mouth opening. No secondary changes were seen on the mucosa overlying the swelling [Figure 1]b. On palpation, inspection findings were confirmed, swelling was tender, bony hard in consistency on buccal aspect. On hard-tissue examination, clinically missing teeth 18, 28, 38, 48 were evident. On the basis of history and clinical examination, provisional diagnosis of odontogenic cyst most probably infected dentigerous cyst in relation to clinically missing tooth 38 was given. The clinical differentials were odontogenic keratocyst, calcifying odontogenic cyst, ameloblastoma, and its variants.

Orthopantomogram revealed a well-defined multilocular radiolucency extending from the cementoenamel junction of tooth 38, involving left side angle, posterior border of the ramus of the mandible, condylar head, sigmoid notch, coronoid process, and anterior border of the ramus of the mandible, to the mesial aspect of tooth 36. There was mild apical third root resorption of tooth 37. Left side of the inferior alveolar nerve canal is intact with impacted tooth 38 close to the nerve canal. The borders were corticated and scalloped; thinning was seen in the angle region with loss of corticated border in relation to the anterior border of the ramus of the mandible; and the condyle architecture was lost. Internal structure revealed multiple large locules resembling soap bubble in the ramus of the mandible [Figure 2]a. Transpharyngeal view of the left temporomandibular joint revealed empty condylar fossa [Figure 2]b.

Figure 2: (a) Orthopantomogram revealing a well-defined radiolucency extending from the cementoenamel junction of 38 to the entire left ramus of the mandible. (b) Transpharyngeal view of the left temporomandibular joint reveals empty condylar fossa. (c) Posteroanterior skull reveals complete loss of the medial and lateral border of the ramus. (d) Computed tomography axial section reveals homogenous hypodensity involving the entire left side of the mandible with bicortical expansion

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Posteroanterior view of the skull revealed a multilocular radiolucency extending from the impacted tooth 38 to the entire ramus of the left side, condyle, and coronoid process with emptying of the condylar fossa [Figure 2]c. Computed tomography (CT) axial section revealed homogenous hypodense region involving the left side of the angle and ramus of the mandible. Another axial section revealed bicortical expansion of the left side of the ramus with loss of medial border of ramus, condylar, and coronoid process architecture [Figure 2]d. Chest radiograph was taken to rule out any lung lesion and it appeared normal. Wide resection of the mandible with margins of 2–3 mm was done under general anesthesia [Figure 1]c.

Histopathological examination revealed dense proliferation of odontogenic epithelium in the form of network. Within the odontogenic epithelium, there were different histological changes noticed in the form of cystic degeneration, acanthomatous changes, aberrant keratinization, and empty spaces. The peripheral cells showed clear picketing fence arrangement with reverse polarity of nucleus in most of the areas. The stromal component was minimum in some areas. There was also predominant vascularity noticed with dilated spaces containing blood. In the proliferative areas, increased numbers of mitotic figures were noticed [Figure 3]. On the basis of histopathological investigations, final diagnosis of AC was made. To rule out any distant metastasis, the patient was later subjected to CT and ultrasound examination of the head and neck, abdomen, and pelvis. There were no significant findings; hence, the patient was kept under regular follow-up.

Figure 3: 100x section revealed dense proliferation of odontogenic epithelium with different histological changes noticed in the form of cystic degeneration, acanthomatous changes, aberrant keratinization, and empty spaces

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Discussion

AC is a rare malignant odontogenic tumor. AC may develop from the epithelial tissue that remains after the development of the teeth and associated structures. They reported 34.6% revealed metastasis, while 23.1% demonstrated local recurrence.^[3]

Similar to ameloblastoma, AC is also more commonly seen in the mandibular region than the maxilla where the ratio between mandibular and maxillary occurrence of AC is reported to be 2:1.^[4] It has a wide age range of occurrence, male predominance with cases reported in patients between 10 and 84 years of age; with a mean age of 30.1 years. In this case report, AC was seen in males, and the site of occurrence was posterior mandible with the entire ramus involvement, which was similar to the review of cases by Benlyazid et al.^[5]

The clinical presentation of AC is variable, such as a cystic lesion with benign clinical features or a large tissue mass with ulceration, bone resorption, and tooth mobility. Swelling, pain, and rapid growth are the most common presenting symptoms. This case presented as a cystic lesion with swelling, pain, and rapid growth.

Clinically, AC causes expansion of the jaw, grows rapidly, frequently causes pain, and often results in perforation of the cortex. Involvement of the nasal cavity is usually related to local invasion of the maxillary ACs.^[6] In this report, although the lesion was rapid in growth, associated with pain, trismus, and cortical perforation, there was no much bicortical expansion evident clinically as the lesion expanded anteroposteriorly. Although regional and distant metastasis is the feature of malignant ameloblastoma, in few cases of AC, these lesions have been known to metastasize mostly to the lung or regional lymph nodes. Macintosh pointed out that the first site of reported ameloblastic metastasis was the lung and originally believed to be due to aspiration from the oral lesion rather than a true hematogenous or lymphatic spread.^[7] This was in contrary to the present report which showed no regional or distant metastasis perhaps because of the early detection of the tumor.

The radiographic appearance of the ACs described in the literature is generally consistent with that of ameloblastomas, except the presence of some focal radiopacities, apparently reflecting dystrophic calcifications. In this report, there was cortical expansion with thinning and perforation, but no evidence of dystrophic calcification. In 1987, Corio et al.^[8] reported that dystrophic calcification is not specific to ACs and can be found in the desmoplastic variant of conventional ameloblastomas.

Painless swelling, trismus, and impacted tooth 38 deceived us to give a provisional diagnosis of dentigerous cyst in relation to unerupted tooth 38, whereas the histopathological diagnosis was AC of primary type. In the updated histological classification of the WHO in 2005, AC is classified as AC primary type; AC secondary type – dedifferentiated, intraosseous; and AC secondary type – dedifferentiated, peripheral (carcinoma ex peripheral ameloblastoma).^[9]

The discovery of carcinoma centrally withon the jaws perhaps entails a complex differential diagnosis. Primary intraalveolar carcinoma and ameloblastic carcinoma represent lesions derived from odontogenic epithelium.^[10] Then, other rare entities such as keratoameloblastoma, acanthomatous ameloblastoma, and squamous odontogenic tumor.^[8]

Wide local excision is the treatment of choice. Radiotherapy and chemotherapy seem to be of limited value; however, these methods need to be considered when there is a locally advanced or metastatic disease not amenable to surgical resection. In this report, surgical excision with dysarticulation was performed, the patient was kept under follow-up every 2 months, and no recurrence was noted till date. Avon et al.^[4] reported the need for adjunctive diagnostic examination after the diagnosis of AC, which includes a workup consisting of CT, chest radiography, and neck evaluation to determine the presence of nodal metastasis. Close periodic reassessment with a long period of follow-up (at least 10 years) is mandatory.

Conclusion

AC is a rare entity of odontogenic tumors that exhibits malignant histologic features in the primary or metastasis. Our present case of an AC is a unique entity that unfolds strange clinical and radiographic features. This case highlights the myriad of presentations of AC and importance of careful histopathological examination of the whole specimen. In view of the fact that recurrence and metastasis in regional lymph nodes and lung are more common, meticulous long-term follow-up of such patients, monitoring of their health status and screening is mandatory.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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