Year : 2009 | Volume
: 21 | Issue : 3 | Page : 114--118
Praveen B Kumar, Vaishali Keluskar, Anjana S Bagewadi, Arvind Shetti, Raghavendra Byakodi
Department of Oral Medicine and Radiology, KLES's VK Institute of Dental Sciences, Belgaum, India
Praveen B Kumar
S/o B. Ramchander Rao, H.No. 9-5-3, Sapthagiri Colony, Karimnagar, Dist. Karimnagar, Andhra Pradesh - 505 002
Ameloblastoma of jaws are common and locally destructive tumors originating from odontogenic apparatus. They constitute approximately 1% of all jaw tumors with 80% occurring in the mandible. Ameloblastoma exhibiting a frank malignancy is a rare entity and occurs in less than 1% of all ameloblastomas. Among the two jaws, ameloblastic carcinoma involving maxilla is extremely rare with only few cases reported so far in the literature. Here we report two cases of ameloblastic carcinoma one involving the maxilla and the other involving mandible, with an aggressive clinical course leading to extensive local destruction of the affected jaws.
|How to cite this article:|
Kumar PB, Keluskar V, Bagewadi AS, Shetti A, Byakodi R. Ameloblastic carcinoma.J Indian Acad Oral Med Radiol 2009;21:114-118
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Kumar PB, Keluskar V, Bagewadi AS, Shetti A, Byakodi R. Ameloblastic carcinoma. J Indian Acad Oral Med Radiol [serial online] 2009 [cited 2020 Feb 18 ];21:114-118
Available from: http://www.jiaomr.in/text.asp?2009/21/3/114/58751
The intraosseous carcinoma arising within the jaw bones is a rare entity, but unique to mandible and maxilla. These carcinomas are either odontogenic in origin derived from the odontogenic epithelial rests, odontogenic cysts, ameloblastomas or nonodontogenic in origin from entrapped salivary gland epithelium. ,,, Carcinomas derived from ameloblastoma have been given the name ameloblastic carcinoma.  Corio et al.  (1987) defined ameloblastic carcinoma as "ameloblastoma in which there is histological evidence of malignancy in the primary tumor or recurrent tumor, regardless of whether it has metastasized". Ameloblastomas constitute approximately 1% of all tumors of the jaws. Most of the reported cases are benign in nature with 80% occurring in the mandible. Rarely, an ameloblastoma exhibits a frank malignancy which occurs in less than 1% of all ameloblastomas. ,,
Various classifications have been given to categorize the odontogenic carcinomas. Pindborg JJ  (1971) and Elzay RP  (1982) had earlier classified odontogenic carcinomas, but these classifications failed to precisely define the intraosseous carcinomas. In 1984, Slootweg and Mόller  emphasized that ameloblastomas may exhibit malignant features other than metastasis and suggested a classification system for malignant tumors with features of ameloblastoma, based on the characteristics of malignancy.
Karan Dhir  (2003) reviewed the literature on maxillary ameloblastic carcinomas. Their review confirmed that maxilla was the least common site for occurrence of ameloblastic carcinoma, as only 17 cases were reported in the literature apart from their case. Herein, we report two cases of ameloblastic carcinoma, one involving the maxilla and the other involving mandible.
A 70-year-old male reported to our department with a swelling on the left side of the face for two years [Figure 1]. The swelling had attained gradually to the present size in two years with associated mobility and exfoliation of teeth.
An extra oral diffuse swelling measuring 5 x 5 cm on the left side of the maxilla [Figure 1] obliterating the nasolabial fold with deviation of the nose to the opposite side. Lips were incompetent. The swelling was nontender, bony hard with pinchable overlying skin. Swelling involved the infraorbital ridge superiorly and the line joining the left commisure and tragus inferiorly, on medial aspect it was crossing the midline upto the right canine eminence and posteriorly it extended beyond the anterior ramus of the mandible. A single left submandibular and submental lymph node was palpable, enlarged and soft.
Intra orally a lobulated swelling measuring 6 x 7 cm was present on the left side of the maxilla extending to the alveolar process on right side obliterating the entire palate, posteriorly involving the soft palate [Figure 2]. Overlying mucosa in the anterior region appeared to be thinned out and numerous minute blood vessels were visible over the surface, whereas the mucosa in the posterior region over the palate was pale in color. A pale appearing lobulated mass was present in the region of left premolars and first molar. On palpation, the swelling was nontender and firm in consistency in the anterior region but soft in the palatal region. There was no ulceration or pus discharge in relation to the swelling and it was noncompressible, nonfluctuant and nonpulsatile in nature. Thus, a provisional diagnosis of minor salivary gland tumor was made. Carcinoma arising from maxillary sinus, primary intraosseous carcinoma and fibrous dysplasia were considered in the clinical differential diagnosis.
The panoramic view [Figure 3] revealed mixed radiolucent and radiopaque lesion extended superiorly above the infraorbital ridge and inferiorly till the alveolar process. Medially it occupied the maxillary sinus and laterally the dentition (maxillary left molars). Diffuse radiopaque foci were present in relation to the maxillary right incisor region. Root resorption was evident.
Para nasal sinus view [Figure 4] revealed obliteration of the left maxillary sinus and partial involvement of the right maxillary sinus.
Microscopic examination [Figure 5] was suggestive of ameloblastic carcinoma. The patient was further subjected to radical surgical extirpation.
A 58-year-old male reported to our department with a swelling on the left side of lower one third of face for two years [Figure 6]. The swelling initially started intraorally as a small painless nodule which gradually attained the present size in two years. The teeth with the associated region became mobile and exfoliated. Patient gave history of beedi smoking for 20 years, two packets per day.
A solitary ovoid well-defined extra oral swelling measuring 4 x 3 cm in size extended anteriorly from the line joining the left corner of mouth and lower border of mandible to the angle of mandible posteriorly. Superiorly, the swelling extended from the line joining the corner of mouth and lower lobe of ear to the inferior border of mandible inferiorly. Swelling was afebrile, nontender, bony hard with pinchable overlying skin. The left submandibular group of lymphnodes was palpable, tender, fixed and firm. The right submandibular lymphnodes were palpable, tender but mobile and f irm.
A diffuse intraoral swelling extended from mandibular left canine region to left first molar region completely obliterating the buccal vestibule [Figure 7]. An ulcerative growth with a whitish halo was seen over the mucosa with respect to the 36 region at the crest of the alveolar ridge. Swelling was nontender and bony hard in consistency except in the ulcerative region where it was firm. Patient's periodontal status was compromised with mild to moderate degree of mobility with the remaining teeth.
A provisional diagnosis of ameloblastoma was made and central giant cell granuloma, odontogenic myxoma, calcifying epithelial odontogenic tumor, ossifying fibroma were considered in differential diagnosis.
The intra oral periapical, mandibular occlusal and panoramic radiographs revealed mixed radiolucent and radioopaque foci extending from mandibular left second molar to right canine with ill defined borders [Figure 8].
The histopathological features [Figure 9] were suggestive of ameloblastic carcinoma and the patient was subjected for surgical management.
Ameloblastic carcinoma is a rare malignant neoplasm that challenges the diagnostic acumen of the clinician. Reliable evidence regarding biological activity is lacking due to scarcity of documented cases.  Malignant ameloblastoma is another entity which is always confused with ameloblastic carcinoma. Malignant ameloblastomas are those which metastasize inspite of benign histological appearance. ,,
In 1983, Shafers , introduced the term ameloblastic carcinoma, to describe an ameloblastoma in which there is malignant transformation in association with less differentiated evidence of metastatic growths. Such tumors show features of ameloblastoma intermingled with those of carcinoma.
Ameloblastic carcinomas occur over a wide range of age from 20 to 40 years ,, with an average age of 30.1 years.  It has a definite predilection for occurrence in mandible with a 7:1 ratio with that of maxilla, but no sex predilection.  The most common clinical signs and symptoms include swelling, pain, trismus, dysphonia and intra oral fistula. , Delay in recognition of maxillary ameloblastomas is common and time from the onset of symptoms to patient seeking treatment is often years. As ameloblastomas originate centrally within bone, early symptoms are usually absent or minimal. A painless mass is a common finding in the mandibular form, while nasal obstruction and localized facial enlargement are frequent findings in maxillary tumors.  These findings were consistent with our cases.
Radiographically, ameloblastic carcinoma resembles multilocular radiolucency similar to that of conventional ameloblastoma, but with numerous dispersed radiopaque zones intermingled with these radiolucencies. , These radiopaque areas represent zones of dystrophic mineralization that are not normally seen in conventional ameloblastomas.  Owing to the aggressive nature of these tumors, perforation of cortical plates is a common feature with extension into soft tissue and distant metastasis to cervical lymph nodes and lungs.  In our cases, a similar multilocular radiolucency was noted with diffuse radiopaque foci.
Controversy exists as per the transformation of a classic ameloblastoma to a malignant lesion. Various authors have shown that metastasizing ameloblastomas were histologically indistinguishable from classical ameloblastomas, ,, while others have identified malignant features in the recurrent or metastatic tumors, usually years after repeated surgical excision suggesting malignant transformation from classical ameloblastoma. ,,
The characterization of carcinoma arising centrally within the mandible and the maxilla is an uncommon but complex problem. The first step in the staging process must be the exclusion metastasis or invasion of bone by tumor from adjacent soft tissue or paranasal sinus. Carcinomas in the jaws metastasizing from primary locations such as the lung, the breast and the gastrointestinal tract may mimic ameloblastic carcinoma and must always be ruled out clinically before that diagnosis is made. ,,
Ameloblastic carcinoma of maxilla is a highly aggressive neoplasm. Radical surgical extirpation is therefore the most preferred treatment.  Meticulous follow up of these cases is essential as recurrence and metastasis in lungs and regional lymph nodes have been reported. ,, In general, the prognosis of the patient is poor.
Rarity of ameloblastic carcinoma of the maxilla poses a diagnostic challenge to the oral diagnostician. Hence, emphasis has to be laid on the clinicopathological characteristics of this tumor which can aid in the early diagnosis and thus facilitate the treatment.
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