AMELOBLASTIC CARCINOMA. A CASE REPORT A.K.P. Ahasan, MDS1, R.P. Parvatty, MDS2, T.S. Bastian, MDS3, K.M. Pai, MDS4

Department of Oral Medicine & Radiology, College of Dental Surgery, Manipal.

ABSTRA�T : Ameloblastoma of the jaw is a rare tumor that stems from dental embryonic remnants

in the mandible or maxilla. It grows slowly, without clinical signs in the early stages. Although it is

considered as a benign tumor, it does invade locally and sometimes metastasizes. Lungs, liver and

kidneys are the common sites for metastasis. Metastasizing ameloblastoma is designated as malig­

nant ameloblastoma. Malignant behaviour of ameloblastoma attributed to the malignant transforma­

tion of the epithelial component, called ameloblastic carcinoma, has also been reported. The differ­

entiation between the entities malignant ameloblastoma and ameloblastic carcinoma is controversial.

A case of ameloblastoma exhibiting aggressive behaviour with possible metastasis to lungs is

reported along with discussion of its features.

INTRODUCTION

Ameloblas toma is a rare benign odontogenic tumor, occuring with an increased incidence in the third and fourth decades. It ac­ counts for 1 % of all oral tumors1• About 80% of the cases are reported in mandible with a defi­ nite predilection for molar-ramus area2• Clini­ cally ameloblastoma is locally invasive and per­ sistent3. Although rare, ameloblastoma do un­ dergo malignant transformation as well as me­ tastasis. Mal ignant ameloblastoma and ameloblastic carcinoma, the two malignant types of ameloblastoma must be differentiated from each other. Former refers to tumors that have metastasized retaining histologic appear­ ance of a benign lesion in both primary and metastatic sites whereas latter term is used to

1- Ex-Postgraduate Fellow

2 - Ex-Postgraduate Fellow

3 - Asst. Professor

4-Associate Professor & Head

Address for commu nication

Dr. A.K.P. Ahsan, MOS (Ausuf)

Sameer Mansion,

Market Road, - 576 123,

designate those lesions exhibiting histologic features of malignancy within a pattern of ameloblastoma4•5• Corio et. al. de fi ne d ameloblastic carcinoma as any ameloblastoma in which there is histologic evidence of malig­ nancy in the primary tumor or the recurrent tumor, regardless of whether it has metastasized6. These lesions are usually aggressive with per­ foration of cortical bone and extensions into floor of the mouth and adjacent soft tissues.

CASE REPORT

A 52 year old male patient was referred to the Dept. of Oral Medicine and Radiology, College of Dental Surgery, Manipal, for evalua­ tion of the lesion in the oral cavity. The lesion was noticed as a small nodule six years prior to the visit and it gradually increased to the present size. Growth was reported to be faster in the last six months. He was taking some indigenous medicine for the same. Patient was a chronic smoker with a history of bronchial asthma for the past five years. Family history was negative for any similar condition.

On general examination, the patient looked chronically ill and weak. Lips were in­ Parkala

Karnataka. competent and a swelling could be noticed near

JIAOMR Vol.11 No. 1, Jan. - Mar. 2000 27

the right angle of the mouth (Fig 1 ). Psoriasiform skin lesions were found on the hands and legs.

lntraoral examination showed poor oral hygiene with few of the upper and lower teeth remaining. A large mass of 7 x 8 cm size was observed in the lower part of the oral cavity (Fig. 2). It was extending from right vallecula and ton­ sils to the left lower canine region. The growth occupied the whole of right floor of the mouth, alveolar ridge, buccal sulcus and the anterior part of the oral cavity. The lesion extended into the labial sulcus pushing the lower lip anteriorly. The tongue was elevated due to the tumor mass. Overlying mucosa showed areas of ulceration due to impingement of the opposing teeth. The mass, on palpation, was firm and non-tender. Bleeding was not seen from the growth. None of the lymph nodes, in the head and neck re­ gion, were palpable. From the history and clini­ cal examination, a provisional diagnosis of ameloblastoma was made.

Patient was subjected to roentgenographic examination which included orthopantomograph OPG and right lateral ob­ lique radiographs. Considering the extensive nature and large size of the tumor, a chest x-ray was also advised. OPG showed a multilocular radiolucency extending from right molar region to left canine region. It also showed two embed­ ded teeth in the radiolucent area. The thickness of the mandible was reduced considerably due to the destructive lesion, however, no pathologic fracture was noticed (Fig. 3). Lateral oblique radiograph of the right side revealed similar find­ ings. Chest x-ray showed a large homogene­ ous opacity over the upper lobe of right lung (Fig 4).

Bone scan with 99Tc radioisotope was done to rule out other metastatic bony lesions. It did not show any abnormal trace concentration except over right mandible.

A biopsy was taken from the oral lesion and sent for histopathological examination. But patient refused to undergo biopsy of the lung

lesion. Microscopically the lesion showed tumor islands in dense connective tissue stroma ar­ ranged in the form of follicles (Fig 5). Periphery of follicles were lined by columnar cells with palisading nuclei and central cells exhibited stellate reticulum like arrangement. the central cells in some follicles showed squamous metaplasia and keratin pearl formation. Pe­ ripheral as well as central follicular cells showed marked pleomorphism, altered nuclear cyto­ plasmic ratio, prominent nucleoli and few mi­ totic figures (Fig 6). Over lying epithelium was hyperparakeratinized strati fied squamou s atrophic to acanthotic. The features were sug­ gestive of ameloblastic carcinoma. Patient was then ref�rred to Dept. of Oncology, Kasturba Hospital, Manipal for further management.

DISCUSSION

Ameloblastoma, the term was coined by Ivy and Churchill in 19307, is considered to be arising from the odontogenic appartus in the jaws. Dental epithelium, enamel organ, rem­ nants of dental lamina, the rests of malassez and epithelial lining of odontogenic cysts are all implicated with the origin of this tumor8. The ameloblastoma is characteristically slow grow­ ing, seldom with a complaint of pain or discom­ fort other than the presence of a swelling. This results in the patient approaching for treatment years after noticing the lesion. In the present case also, the patient had the swelling for six years. Although there was a gradual increase in size of the swelling, absence of any discomfort led to the neglect, allowing the growith to reach the present size. Ameloblastoma, in mandible, is quite often associated with impacted teeth2, as in our case where two impacted premolars were present within the tumor.

Both malignant ameloblastoma and ameloblastic carcinoma show metastasis and the most frequent site is lungs, followed by liver and kidney9• Some cases of single deposits in lungs can be explained by local extension and

28 JIAOMR Vol.11 No. 1, Jan. - Mar. 2000

Fig. 1 : Lateral profile view showing protrusive lips

Fig. 3 : OPG revealing impacted premolars in a multilocular radiolucency

Fig. 5 : Photomicrograph of H&E stained section showing follicles characteristic of

ameloblastoma (x10)

Fig. 2 : Intra-oral view showing the lesion

Fig. 4 : Chest x-ray with a large opacity over right lung

Fig. 6 : Areas showing cellular pleomorphism, prominent nucleoli and altered nuclear cytoplas­

mic ratio (x 40)

JIAOMR Vol.11 No. 1, Jan. - Mar. 2000 29

aspiration3• In this case, the patient had a le­ sion in the upper lobe of right lung, which could not·be confirmed histologically as a metastatic lesion. However the clinical features and extent of the primary tumor along with the position and characteristics of the lung lesion point towards a possible metastatic lesion.

The microscopic pattern of tumor islands arninged as follicles in a dense connective tis­ sue stroma is typical of follicular ameloblastoma. The features like pleomorphism, altered nuclear cytoplasmic ratio, vesicular nuclei with promi­ nent' nucleoli seen among the peripheral colum­ nar �rnd central stellate cells are histologic evi­ dences of malignancy. The above picture corre­ lates with that of ameloblastic carcinoma, where a combination of features of ameloblastoma occur with a less-differentiated morphology5•

Treatment depends on the extent and lo­ cation of the lesion, type of ameloblastoma, soft tissue involvement, age and condition of the patient10• The various treatment modalities used are surgery, radiotherapy, cautery, cryotherapy etc11• The ability to predict behaviour, based on clinical, radiographic and microscopic features is paramount to appropriate treatment for avoid­ ing recurrence and undue morbidity. However, regardless of the type of treatment, long term peri�dic follow-up for recurrence is of utmost importance.

REftRENCES

1. 'Lucas RB, Pathology of tumors of the oral tissues. Edinburgh : Churchill Livingstone, 1976; 30.

2. Ueno S, Nakamura S, Mushimoto K, Shirasu

R. A clinicopathologic study of Ameloblastoma. J Oral Maxillofac Surg 1986;44:361-365.

3. Small IA, Waldron CA. Ameloblastomas of the jaws. Oral Surg Oral Med Oral Pathol 1955;8:281-297.

4. Shafer WG, Hine MK, Levy BM. A textbook of oral pathology. 4th ed. Philadelphia: W B Saunders, 1983; 280-281.

5. Slootweg PJ, Muller H. Malignant amelo­ blastoma or ameloblastic carcinoma. Oral Surg Oral Med Oral Pathol 1984;57:168-179.

6. Corino RL, et al. Ameloblastic carcinoma: A clinicopathologic study and assessment of eight cases. Oral Surg Oral Med Oral Pathol 1987;64:570-576.

7. Ivey RH, Churchill HR. The need of a stand­ ardized surgical and pathological classification of tumors and anomalies of dental origin. Am Assoc Dent Sch Trans 1930;7:240-245.

8. Thoma KH. The pathogenesis of the odontogenic tumors. Oral Surg 1951;4:1262.

9. Ueda M, Kosaki K, Kaneda T, Imaizumi M, Abe T. Doubling time of ameloblastoma metastasizing to the lung: Report of two cases. J Cranio Maxillofac Surg 1992;20:320-322.

10. Williams TP. Management of amelo­ blastoma: A changing perspective. J Oral Maxillofac Surg 1993;51:1064-1070.

11. Gardner DG. Nomenoclature, diagnosis and treatment of ameloblastoma. In: Worthington P, Evans JR eds. Controversies in oral and maxillofacial surgery, Philadelphia: W B Saunders Company, 1994;301-314.

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