AMELOBLASTOMA: A SURVEY OF199 CASES IN THE UNIVERSITYCOLLEGE HOSPITAL, IBADAN,NIGERIAH. A. Ajagbe, DDS, MSc, and J. 0. Daramola, BDS, FDSIbadan, Nigeria

In a study of occurrence of tumors of the jawseen in the University College Hospital over a 24-year period, 199 cases of histologically diag-nosed ameloblastoma were found. Notable fea-tures of these lesions were extreme size at pre-sentation and high frequency of recurrence.Ameloblastoma ranks next in frequency to fi-broosseous lesions and salivary gland tumors inthis community. The incidence in men exceedsthat of women. The mandible was the location inover 85 percent of the cases. Six cases weresuspected to have turned malignant followingmultiple surgical operations.

Ameloblastomas are well-publicized, ectodermal,odontogenic tumors that are reported to constituteabout 1 to 3 percent of tumors and cysts of the jaw.'The tumor is seen worldwide with no proven racialpredilection. Several reports25 have well documentedthe nature ofthis tumor in Nigerian patients. Others6'7have, in small series covering short periods, comparedthe relative incidence of ameloblastoma with otherjaw tumors in West Africa. The objective ofthis article

From the Department of Oral and Maxillofacial Surgery, Universityof lbadan, University College Hospital, Ibadan, Nigeria. Requestsfor reprints should be addressed to Dr. H. A. Ajagbe, Departmentof Oral and Maxillofacial Surgery, University of Ibadan, UniversityCollege Hospital, Ibadan, Nigeria.

is to summarize a retrospective study of cases ofam-eloblastoma seen in the Univeristy College Hospital,Ibadan, during a 24-year period (1960 to 1983); tocompare its incidence with other major jaw tumorsseen during the same period; and to highlight the ag-gressive characteristics seen in some of the amelo-blastic lesions.

METHODSThe sources of information in the cases are from

the cancer registry and the surgical daybook of theDepartment of Pathology, University College Hos-pital, Ibadan. Where information in case records wasinadequate or in doubt, the surgical slides were re-viewed to confirm or reject the diagnosis of amelo-blastoma. All cases included in this series have beenhistologically confirmed. The authors were involved(in one way or the other) in the management of ap-proximately one halfofthe patients, whereas the caserecords of the remaining patients were reviewed forthe course of their disease:

RESULTSIncidenceDuring the 24-year period covered by this study,

1,302 histologically diagnosed jaw tumors, excludingodontogenic cysts, were found in the records of theDepartment of Pathology. Of these, 199 (15.28 per-cent) were ameloblastomas (Table 1). Ameloblastoma

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TABLE 1. MAJOR PRIMARY JAW LESIONSSEEN IN 24-YEAR PERIOD

FrequencyLesions Total No. (%)

Fibroosseous lesions 290 22.27Salivary gland tumors

Benign 128 9.83Malignant 105 8.06

Ameloblastomas 199 15.28Squamous cell carcinoma 197 15.13Burkitt's tumor 125 9.60Other sarcomas 116 8.90

TABLE 2. SEX DISTRIBUTION OFAMELOBLASTOMAS OF THE JAWS

Type ofAmeloblastoma Male Female Total

Simple ameloblastoma 102 77 179Adenomatoid

odontogenic tumor 8 10 18Melanoameloblastoma 2 - 2

Total 112 87 199

is exceeded in frequency only by benign fibroosseouslesions and salivary gland neoplasia of all types.

Sex and AgeThere were 112 (56.3 percent) men and 87 (43.7

percent) women, giving a ratio of approximately 4:3(Table 2). The recorded ages at presentation of pa-tients suffering from simple ameloblastoma rangedfrom two years to above 80 years with an average ageof approximately 32 years. Patients who were treatedfor adenomatoid odontogenic tumor (adenoamelo-blastoma) were predominantly within the second de-cade of life, while the two male cases of progonoma(melanoameloblastoma) were aged eight months andfour months at presentation. Sixty-four (32.2 percent)patients were under 20 years of age at the initial hos-pital attendance.

Site

Of the 167 cases of simple ameloblastoma withknown sites, 150 (90 percent) were located in the

TABLE 3. SITE DISTRIBUTION OFAMELOBLASTOMAS OF THE JAWS

Type of Man- Max- Un-Ameloblastoma dible illa known Total

Simple amelo-blastoma 150 17 12 179

Adenomatoidodontogenictumor 9 9 18

Melanoamelo-blastoma 2 2

Total 159 28 12 199

mandible while the rest were found in the maxilla(Table 3). All parts of the mandible were variouslyaffected. Adenomatoid odontogenic tumor, on theother hand, had equal distribution to both the maxillaand the mandible. The two cases ofprogonoma werelocated in the maxilla. The canine and premolar areaswere the predominant site of simple ameloblastomaand its variants located in the maxilla. All recordedcases of ameloblastoma were unifocal. Some lesionswere extensive, and extended from the ramus of oneside of the mandible to the other side.

Clinical FeaturesThe physical features and radiologic appearances

of the tumors were similar to those already docu-mented by earlier reports. Two clinical features ofsimple ameloblastoma seen in this series need to behighlighted-the recurrence rate and the aggressiverate of regrowth. Some patients returned after only afew months with a recurrence, while other cases ofameloblastoma remained quiescent for several yearsbefore there was evidence of regrowth. There was thecase of a 72-year-old patient who first had a hemi-mandibulectomy for ameloblastoma 22 years beforewho returned with a soft tissue recurrence of the le-sion. Following the excision of the recurrence, theuncontrollably aggressive rate ofthe tumor's regrowthwas the known cause ofthe patient's death 18 monthslater. Nineteen of the patients have had as many asfour or more surgical excisions oftheir tumors. Mostrecurrent cases remained local and benign throughouttheir course, but in six patients who had multipleoperations, the unusually aggressive rate of regrowthwas the known cause ofdeath. Those cases were con-sidered clinically malignant.

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TreatmentResection within an adequate margin is the ac-

ceptable treatment procedure for ameloblastoma. Al-though most of the tumors in this series were treatedaccording to this principle, there were cases in whichthe size and location ofthe lesion and the age or healthstatus ofthe patient made modification ofthis generalprinciple necessary. For instance, some large sym-physeal lesions were saucerized rather than totally re-sectioned when it was obvious that postoperativeprosthetic reconstruction would be impossible andthat the patient's life would be unnecessarily at riskifthe lesion was totally excised. However, in selectedcases when reconstructive prosthesis was done, vary-ing degrees of long-term success were observed. Theprimary objective of treatment was always the re-moval ofdisease and restoration offunction as muchas possible. Appearance was the least of the patients'concern.

Follow-UpIt was difficult to obtain an accurate recurrent

number of ameloblastomas in this series because ofscanty follow-up records. It was generally presumedthat ifa patient failed to report for the regular follow-up appointments, he was either completely free ofthedisease and did not consider it necessary to continueto attend, or that the regrowth ofthe tumor was slowand not debilitating enough for the patient to seekfurther surgery. Some aggressive recurrent cases wereknown to have resulted in patients' deaths. These werethe cases that changed in their clinical behavior andprobably histologic nature after multiple surgical in-terventions.

DISCUSSIONAmeloblastoma is a tumor that has a worldwide

distribution. Although the controversy over themethod of treatment of ameloblastoma is virtuallyresolved, there is yet no agreement over the reported8'9racial predilection of the tumor. So far, the descrip-tions in the literature do not allow any conclusionsto be drawn in relation to racial predilection, as somereports were based on "corrected"8 values, while oth-ers disregarded the racial population ratio in thecommunity from which the patients were drawn.9

In assessing reports that came out of studies, sur-veys, and reviews on jaw tumors in Africa, Mosa-domi4 attributed the hitherto "observed" high inci-

Figure 1. Ameloblastoma involving the entire mandible.Scars on the lesion show attempts made by traditionalhealers at "draining bad blood" from the tumor

dence in Africans to the "harvesting phenomenon."He concluded that "it is still not possible to determineaccurately the incidence ofjaw tumors in most Af-rican countries because of epidemiologic obstacles."Conclusions ofa high incidence ofameloblastoma inAfricans or black people have been hasty and unre-liable. Ameloblastoma is numerically in third placeamong alljaw lesions seen in University College Hos-pital during the period under review.

All the patients suffering from ameloblastoma wereNigerians. Men were generally more frequently af-fected than women, but this may not always be so.'0The ratio of men to women in this review was ap-proximately 4:3. The average age of 32 years in thisseries may be inexact, as the ages of older patientswere often estimated. Because the ameloblastoma isslow growing and is not usually immediately life-threatening, patients have been known to have de-layed for long periods of time before presenting fortreatment (Figures 1 to 3). In one reported" case,there was a delay of 53 years. In the series reported

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Figure 2. Areas of opacities and lucencies can be seenon posteroantenior view of patient's mandible

here, the patients often presented unreliable historiesof time of onset. It could be estimated, though, thatjudging from the extremely large size, some of theselesions had been present for a long time before thepatients sought treatment.

It is not known why the mandible is more suscep-tible than the maxilla to ameloblastoma. In theory,the primordium ofthe odontogenic apparatus, or cellswith potentiality to form ameloblastoma, is presentin both upper and lower jaws; therefore, the twoarches could be expected to be equally susceptible.Akinosi and Williams2 sugested that sepsis and ir-ritation in the lower anterior teeth might be respon-sible for the unusual frequency ofsymphyseal locationof ameloblastoma in Nigerians. Adekeye,5 however,did not find this high anterior location in his seriesof 109 Nigerian patients who were treated for ame-loblastoma.The erruptive irritation of the mandibular teeth

may be a promotional factor in the development ofameloblastoma in the posterior area of the arch.Some common clinical features of the simple am-

eloblastoma are slow, persistent growth and resistanceto eradication as evidenced by frequent recurrences.Repeated surgical operations following recurrencesare possibly responsible for the cases of malignantameloblastoma reported in the literature. Six (3 per-

::4 a~~~~~

Figure 3. Radiograph of the excised mandible. Solidand cystic areas are both present in the lesion

cent) of the cases in this senes were considered ma-lignant because of their clinical behavior, and in atleast one case, a change in histologic appearance andmetastasis to the lung was observed.'2

Literature Cited1. Small IA, Waldron CA. Ameloblastoma of the jaws. Oral

Surg 1955; 8:281-297.2. Akinosi JO, Williams AO. Ameloblastoma in Ibadan, Ni-

geria. Oral Surg 1965; 27:257-265.3. Daramola JO, Ajagbe HA, Oluwasanmi JO. Ameobblastoma

of the jaws in Nigerian children. Oral Surg 1975; 40:458-463.4. Mosadomi A. Odontogenic tumors in an African population.

Oral Surg 1975; 40:502-521.5. Adekeye EO. Ameloblastoma of the jaws: A survey of 109

Nigerian patients. J Oral Surg 1980; 38:36-41.6. Kovi J, Laing WN. Tumors of the mandible and maxilla in

Accra, Ghana. Cancer 1966; 19:1301-1307.7. Anand SV, Davey WW, Cohen B. Tumours of the jaws in

West Africa. Review of 256 patients. Br J Surg 1967; 54:901-917.

8. Kegel RFC. Adamantine.epithelioma. Arch Pathol 1937;23:831-843.

9. Schulenburg CAR. Adamantinoma. Ann R Coll Surg EngI1951; 8:329-353.

10. Robinson HBG. Ameloblastoma: A survey of three hundredand seventy-nine cases from the literature. Arch Pathol 1937;23:831-843.

11. Zatti (1894). Cited by Robinson, HBG. Ameloblastoma.Arch Pathol 1983; 23:831-843.

12. Daramola JO, Abioye AA, Ajagbe HA, Aghadiuno PU.Maxillary malignant ameloblastoma with intra or bital extension:Report of case. J Oral Surg 1980; 38:203-206.

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