AMELOBLASTIC CARCINOMA: A CASE WITH CERVICALNODE AND PULMONARY METASTASES

SP Khoo, ST Ong. Ameloblastic Carcinoma: A case with cer-vical node and pulmonary metastases, Annals Dent UnivMalaya 1998; 5: 49-52

ABSTRACTOdontogenic carcinomas of the jaws are subclassified intomalignant ameloblastoma, ameloblastic carcinoma and pri-mary intraosseous carcinoma arising from within the bone.These may arise from residual islands of epithelium derivedfrom dental lamina or epithelial lining of dental cysts.Ameloblastic carcinoma is extremely rare. An aggressive caseof ameloblastic carcinoma occumng in a 59-year-old Malayman is presented. Wide excision of the primary lesion withradical neck dissection was carried out. He developed lungmetastasis 4 months post-operatively. Despite chemotherapyupon discovery of lung metastasis, he expired 7 months fol-lowing the initial diagnosis.

Keywords: Ameloblastic carcinoma, aggressive lesion, necknodes metastases, pulmonary metastasis, malignantameloblastoma.

INTRODUCTIONAmeloblastoma is considered the most common epithelialodontogenic neoplasm, representing about I% of all oralturnours with 80% occurring in the mandible and 20% in themaxilla (1,2). The behaviour of ameloblastomas is essential-ly persistent, locally invasive but not malignant.

The current WHO classification of odontogenic carci-nomas into three types namely, malignant ameloblastoma, pri-mary intraosseous carcinoma, malignant variants of otherodontogenic tumours and malignant changes occurring inodontogenic cysts remains unchanged from its original clas-sification in 1972 (3,4). Elzay and coworkers (5) have pro-posed a subclassification of these malignant tumours and thisin turn has been modified by Siootweg and coworkers (6). Inthis classification the term "ameloblastic carcinoma" is usedto describe the tumour which demonstrates histological evi-dence of malignant transformation of the ameloblastoma-likeepithelial component in the primary tumour whether or notit has metastasized.

Ameloblastic carcinoma generally occurs in themandible affecting the average age group of 30 - 33 yearswith the lung being the commonest site for metastasis (6,7).The following report is a case of ameloblastic carcinoma withlung metastasis which developed 4 months after the initialdiagnosis.

Case report:A 59-year-old Malay man came to the Department of Oral &Maxillofacial Surgery with a complaint of swelling in thelower alveolus. He had first noticed the swelling about onemonth previously. The swelling had rapidly increased in sizeand had became painful for the past one week. There was nodifficulty in eating and no noticeable weight loss.

I Khoo Suan Phaik2 Ong SiewTin

Associate ProfessorDepartment of Oral Pathology,Oral Medicine&Periodontology

2 LecturerDepartmentof Oral and Maxillofacial Surgery

Faculty of DentistryUniversityof Malaya50603 Kuala Lumpur,Malaysia

His significant medical history included ischaemic heartdisease and myocardial infarction two years previously. Hehad been taking antihypertensive medications which includeIsordil, Adalat, Betaloc and aspirin.

Clinical examination revealed a fairly fit man with noother signs and symptoms elsewhere. There was a firm,indurated and ulcerated swelling on the right side of the chin(Figure 1). There was anaesthesia on the right mental region.Two right upper cervical lymph nodes were palpable.

Intra-oral examination showed a completely edentu-lous mouth. An ulcerated and proliferative lesion was

Figure 1 Extra-oral appearance of the lesion on presentation

50 Annals of Dentistry, University of Malaya Vol. 51998

Figure 2 True occlusal view of the anterior portion of the lesionshowing an osteolytic lesion with irregular destruction of the lin-

gual and buccal cortices.

present over the right side of the edentulous mandible.Bony expansion was evident on the right buccal region andthis extended across the midline onto the left side. The rightbuccal mucosa was indurated and the mouth opening wasrestricted. It was obvious that a bony lesion had perforatedthrough both the oral mucosa and skin, highly suggestive ofa malignancy.

Occlusal radiographs of the mandible showed a multi-locular, osteolytic lesion with no distinct margin extendingfrom the right to the left edentulous mandible (Figure 2). Thebone was expanded to the left of the midline. A chest radi-ograph (Figure 3), CT scans of the brain, liver and bone weretaken at the frst consultation and these were negative for evi-dence of tumour.

Incisional biopsies were performed at representativesites, namely the skin, ulcerated mucosa and of the cystic cav-ity at the left side of the mandible. All three specimensshowed similar histological features as discussed below.

Histopathology:Microscopic examination revealed that the tumour was com-posed of large sheets and anastomosing epithelial strands con-sisting centrally of stellate reticulum-like cells with ovoidnuclei. Preameloblast-like cells were bordering the epithelial

Figure 3 Pre-operative chest radiograph appearance.

strands and the large sheets. The intervening stroma wasslightly oedematous. In areas cellular and nuclear pleomor-phism was evident. In such areas, the periphery of cell nestsexhibited a columnar morphology. These cells containedpleomorphic nuclei with mitotic figures. Squamous meta-plasia together with infiltrating well-differentiated squamouscell carcinoma islands were present in these areas. Thetumour infiltrated diffusely into the surrounding soft tissues.(Figure 4).

Treatment:Surgical excision with primary reconstruction of themandibular defect was the mode of treatment chosen for thispatient. Segmental resection from angle to angle of themandible with wide excision of the involved mucosa and skinwas carried out. A frozen section of the two right deep cer-vical lymph nodes showed infiltration by tumour. On thebasis of this fnding, a right radical neck dissection was per-formed. A frozen section of the cervical lymph nodes showedtumour involvement and hence these were removed in theneck dissection. A 20cm length of fibula graft with the over-lying skin was harvested from the left leg. The fibula graftwas fixed to the remaining mandibular rami using miniplates.The vessels were anastomosed to the left facial artery andvein while the skin was used to provide both intra-oral coverand reconstruction of skin defect. The grafted site healed

Ameloblastic carcinoma: A case with cervical node and pulmonary metastases 51

Figure 4 Photomicrograph showing islands of ameloblastic carci-noma infiltrating adjacent fibrous connective tissue stroma.Dedifferentiation within areas of conventional ameloblastoma isevident (H & EX 200).

without fistulation and there was satisfactory oral seal despiteobvious facial defect. He was able to take soft diet andspeech was acceptable.

Four months post-operatively, he was admitted for acuteshortness of breath due to pneumonia. A chest radiographtaken showed patchy lung deposits (Figure 7), most proba-bly representing secondaries from malignant ameloblastomaof the mandible. The patient refused a biopsy of the lunglesion. He was treated by the physician in another hospital butthe patient passed away two months later. There was also noconsent for an autopsy.

DISCUSSIONCarcinomas derived from ameloblastomas have been givenmany designations such as malignant ameloblastoma (I),metastatic carcinoma (6) and primary intra-alveolar epider-moid carcinoma (8). In the most recent classification ofodontogenic tumours by the World Health Organisation,malignant ameloblastoma is clearly defined as "a neoplasmin which the pattern of an ameloblastoma and cytological fea-tures of malignancy are shown by the primary growth in thejaws and/or by any metastatic growth"(3).

Slootweg and Muller (6) subclassifed odontogenic car-cinomas into three categories as they felt that these tumoursexhibit considerable differences in biological behaviour andhistomorphology. The sub-classification is as follows:Type I. Primary intraosseous carcinoma ex odontogenic

cyst.Type 2. A. Malignant ameloblastoma

B. Ameloblastic carcinoma, arising de novo, exameloblastoma or odontogenic cyst.

Type 3. Primary intraosseous carcinoma arising de novoA. NonkeratinizingB. Keratinizing.

As a result of their subclassification, malignantameloblastoma and ameloblastic carcinoma were distin-guished from each other. The former is a term which shouldbe reserved for those lesions that, in spite of a seeminglyinnocuous histology, have given rise to metastatic growth.The latter however, is a term for lesions that combine features

Figure 5 Chest radiograph 4 I1wnthspost-resection of the mandibu-lar lesion. Bilateral pleural effusion with hazy opacities (arrow-heads), possibly representing metastases.

of ameloblastoma with a less-differentiated histomorphology.Accordingly hence, this case could be described as malignantameloblastoma according to the WHO classification (3) butwould fit into Slootweg and Muller's (6) classification as atype 2B odontogenic carcinoma (although evidence of lungmetastases could not be obtained in this patient).

Since Elzay's review (5) and classification of odonto-genic carcinoma, other workers have reported arneloblasticcarcinoma as a separate entity. Corio et al (7) reviewed eightcases of ameloblastic carcinoma and found four cases whichappear to arise from a cyst lining. The mean age ofthesepatients was 30.1 years. Seven cases involved the mandiblewhilst one involved the maxilla. Only one case presented withcervical metastases. The most common presentation wasswelling, followed by pain and/or rapid growth. Radio-graphically, most cases presented as an ill-defined destructiveradiolucency with focal radiopacities. Perforation of the buc-cal and lingual plates also occurred together with evidence ofroot resorption. The lesions were aggressive, extendingbeyond bone into adjacent soft tissue. Histologically, theselesions exhibited features of conventional ameloblastomabut the epithelium displayed various cytological features ofmalignancy. The five year survival rate was not presented bythese authors.

52 Annals of Dentistry, University of Malaya \-hl. 5 1998

Slootweg and Muller studied all cases in the literaturereported as malignant ameloblastoma (6). There were 13males and 10 females with ages between 4-75 years and amean age of 33.5 years. Metastasis occurred most common-ly to the lung. These lesions appear as radiopacities on chestradiographs. Generally, it appeared that there was a signifi-cant time span between initial treatment and the occurrenceof metastasis. However, when the disease had spread, deathoccurred within a year or so. Histologically, they found twocases in which the metastasis exhibited a less differentiatedpattern than the primary tumour. A dedifferentiation patternwas noted in the primary and metastatic growth in ninecases. Metastatic disease was not present in ]4 casesalthough the primary ameloblastoma had undergone anaplas-tic transformation.

Subsequent cases of ameloblastic carcinoma have beenreported by Andersen and Bang (maxilla) (9), Domer et al(mandible with pulmonary metastasis) (10), McClatcheyand coworkers (peripheral ameloblastic carcinoma) (1]),and Bruce and Jackson (aggressive lesion in the mandible)(12).

The case reported here presented centrally and periph-erally with cervical lymph node spread. Radiographically thistumour presented as an ill-defiined radiolucency. Like Bruce& Jackson (12) no radiopacities were noted within the pri-mary tumour. However, the metastatic lung lesions present-ed with multiple radiopacities. The histological features of theprimary tumour were similar to those described in the liter-ature i.e. consisting of general features of a conventionalameloblastoma but with cyto]ogical features of malignancyie. ameloblastic carcinoma.

The clinical course of ameloblastic carcinoma is typicallyaggressive with extensive local destruction. Local recur-rences are common and so are metastases to the neck andlung (1, 6,7). The clinical course of this case was moreaggressive than the cases described in the literature. Thepatient possibly had lung metastasis three months post-oper-atively and from the point of initial diagnosis the patient sur-vived only seven months despite radical surgery andchemotherapy. Corio and coworkers (7) reported three ofseven cases which had recurrences within a year. Slootwegand Muller (6) noted that cases which showed dedifferenti-ation in both the primary and metastatic growth died with twoyears after metastasis. More recently, Bruce & Jackson(12)reported an aggressive case with early metastasis to the leftlung.

There is ample evidence in the literature that so-called"benign" ameloblastoma can dedifferentiate with time andmultiple inadequate surgical procedures are associated withmetastasis(l2). The length of time taken for dedifferentiationof the tumour is unknown. The usefulness of radical necksurgery in the management of ameloblastic carcinomaremains debatable. Radiotherapy appears to be of limitedvalue for ameloblastic carcinomas and chemotherapy is yetunproven (12). From a clinical viewpoint, ameloblastic car-cinoma is an extremely aggressive neoplasm and any modeof treatment chosen should be aimed at preventing recur-rences.

Histogenetically, ameloblastic carcinoma like otherodontogenic carcinomas, may arise de novo from remnantsof the dental lamina or from odontogenic cysts and may belocated centrally in the jaws or peripherally in the surround-ing mucosa (3,13). However, little is known of the relation-ship between the different histologic patterns of odontogeniccarcinomas and their prognosis. Corio et al (7) stated:"Although the primary intra-alveolar carcinoma and theameloblastic carcinoma exhibit some clinical differences,their histological features are similar enough to suggest a his-togenetic relationship. It is possible then that the primaryintra-alveolar carcinoma may represent a less differentiated,usually nonkeratinizing form of ameloblastic carcinoma bothlesions being derived basically from odontogenic epithelialremnants".

In conclusion therefore, due to the rarity of this tumourand paucity of knowledge of its relationship between the his-tological patterns and its clinical course, it is rational to treatthese lesions aggressively with wide excision.

REFERENCES1. Carl RF, Halperin V. Malignant ameloblastomas from

1953 to 1966. Review of the literature and report of acase. Oral Surg 1968; 26: 5]4-22.

2. Shafer WG, Hine MK, Levy BM. A textbook of OralPathology (ed 4), Philadelphia, PA Saunders, 1983; p276.

3. Kramer IRH, Pindborg JJ, Shear M. HistologicalTyping of Odontogenic Tumours (ed. 2) Springer-Verlag 1992; pp24-5.

4. Pindborg JJ, Kramer IRH, Torloni H. Histological typ-ing of odontogenic tumours, jaw cysts and alliedlesions. Geneva: World Health Organization. 1972; pp35-6.

5. Elzay RP. Primary intraosseous carcinoma of the jaws:review and update of odontogenic carcinomas. OralSurg 1982; 54: 299-303.

6. Slootweg PJ, Muller H. Malignant ameloblastoma orameloblastic carcinoma. Oral Surg 1984; 57: ]68-79.

7. Corio RL, Goldblatt LI, Edwards PA, Hartman KS,Wright-Patterson. Ameloblastic carcinoma: A clinico-pathologic study and assessment of eight cases. OralSurg 1987; 64: 570-6.

8. Shear M. Primary intra-alveolar epidermoid carcinomaofthe jaw. J Pathol ]969; 97: 645-51.

9. Andersen E, Bang G. Ameloblastic carcinoma of themaxilla. J Max-Fac Surg. 1986; 14: 338-340.

10. Domer L, Sear AJ, Smith GT. A case of ameloblasticcarcinoma with pulmonary metastases. Br J OralMaxillofac Surg 1988; 26: 503-510.

11. McClatchey KD, Sullivan MJ, Paugh DR. Peripheralameloblastic carcinoma: a case report of a rare neo-plasm. J Otolaryngol ]989; 18: 109-111.

12. Bruce RA, Jackson IT. Ameloblastic carcinoma: reportof an aggressive case and review of the literature JCranio-Max-Fac Surg ]991; ]9: 267-271.

13. McClatchey KD. Tumours of the dental lamina: aselective review. Semin Diagn Pathol 1987; 4: 200-204.