AMELOBLASTIC
ODONTOMA
Report of a Case
T
I-IE classification and nomenclature of odontomas leaves much to be desired as regards consistency. One acceptable scheme nould stem to bc that published by Pindborg,” who defines the odontoma as an odontogenic t,umor thal has at,tained a degree of tissular differentiation in which dentine, enamel, and often also eementum haw developed. Pindborg divides odontomas into three main groups : amelobastic, complex, and composite. Thc~ :rineloblastic~ odontomn does not constitute an indepcndcnt ~YOLI~I, bow-ever, l)ut lllily 1~ regarded as an intermediate stage in the de\-elopment of the odontoma. The earliest. stage in this chain of development is a genuine soft-tissue tumor, which 11as been dcsignated an ameloblastic fibroma or soft odontoma, and the mature product is a completely mineralized odontoma. of the complex or the composite type. Synonyms for ameloblastic odontoma are adamanto-odontonL~~~ soft and calcified odontoma,2 and odolltoarllclok)lastoma.” In Thoma ‘s” often-quot cd schnme the ameloblastic odontoma secws to lx included in the complcs otlontoma group. The ameloblastic odontoma presents a varied histologic picture. It contains and somet,imes cttrnrntunl 1. hard-tissue substances (~mmely, derttinc, enamel, accumulations of arnelol)l;~st-lilie epithclia 1 cells arranged in the form ol’ islands or strings, and connective tissue which is usually embryonal in typ(l. E’rom the number of GLSWpllblished, ii. would seem that. tht: ameloblastit odontoma is seldom encountered and is the least common of the t hrct: groups. This is consistent with our personal expericnec. The clinical symptoms of odontoma arc usuall,v insignificant, and the diagOften a tooth nosis is generally made on routine examination of the dentition. The odontoma grows slowly and can is missing, with no history oE cxtrackioii. gradually cause local swelling in the jaw. Other symptoms, such as neuralgic pains due to compression of the nerve, arc less common. Odontomas may som+ t,imes become infected, and the p~~ess nlay consequently be diagnosed as osteilis in the jaw with sequestra.
Routine exaxklation at the school The patient was a lo-year-old girl. revealed a swelling at the site of the loaner left first molar, which was missing. was admitted to the Caroline Hospital for further examination. nostic
From the Ear, Nose Department (Head:
and Throat Clinic Prof. K. Lindblom),
(Head: Prof. Karolinska
726
T. Skoog) Sjukhuset.
dental clinic The patient
and the RoentgendiagStockholm 60. Sweden.
Roentgeuographic examinations (Figs. 1 allcl 2 ) sl~ow~~~l, at tilt site of tile missing snrrouud~vl 1)~ a narrow sclerotic tooth, a rocntgenolucent area about 1 cm. in diameter, In this region the mandible was slightly swollen aud thcx cortical layer was thinned, hrdrr. The roentgenoluccwt arca continued ~listally as a process 1~0th orally and vrstibularly. rrl the rotwlgenolucent lkassing over the ~~rowns of the still unerupted secoud and tllircl niolars. AI Ilcciduous tooth \~-a9 situated wgion there \vr:re small areas of a granular mineralization. in contac~t with the anterior margin of the translucent :LUS:~.xtld its distal root Ilad l~ecn A provisional diagnosis of immature odoutoma 1~:~s made. nwrl,fY1.
Fix. :i.-Photomicrograph of xmeloblastic odontnma. The tissue in this area conr;i.sts of epithelisl cells and connective tissue of cmbrgonal type. (Hematouylin and cosin &tin. Mwniflcation. x216 ; educed gi,.) OpWUtiOra.--The tumor was Cstirp:~trd urlclcr intul,iLtioll narcosis. .\ scy+orh I.lrrougll the gingiva and the prriosteum was malle in the vestihulum frorrl tllc wnord Ivft ~)wmol;tr irb the third molar. The lateral part of the mandiMc was esposcd 11~
IfistoTogic examination of the tumor showed that it \!as composed of counectire tissw of the embryonnl type, containing small groups ant1 strings of’ cpithclinl cells (Fig. 3). 1x1 palisade formations the periphery of the epithelial accumulations there were, iu many placq in the groups some ol’ thcx ct,llr wvre of tht stcll:Lte of cylindrical epithelial cells. Centrally type, and a transition to small epithelium-covered cysts I\-as olwc~rwd. Tllew was 110 appreciOn the surface of the tumor, connwt ire tissue (rirh in collagen :tble cpll polymorphism. rlt~rnarcntctl fibers] and some bone fragments were seen; the latter \vclre ill places tliffusely from the tumor itself. The bone fragments in some sections JRW~ eroded 1r.v I lkc tumor tkuc. In the tumor nnkss thcw were small mineralizccl nre:\S There was no distinct encapsulation. in which mirroroentgenographic examination rwcalecl no tlcfinite strudurc (Fig. -2). In the decdcificd spwimrn these were found to consist of immatur~~ ctlrwnel, the organic sullstance of which did not dwompose on decalcification (Fig. 3 I. On part of that cnamc~l -It other placw t1rtbt.e ww ;1 .*rll:ill Illc’st~ll~~ll~-lll:ll <‘OX t;urface thaw were ameloblasts. :,11 1wr1> This migllt il:t\-f~ rrpws“ntrrl vring which stained red with vnn Giesulr ‘s stain. stage of dcntine matrix ; however, since no dcntinal tul,ulvs 1~0ul(l lw seen, it coulll not lK! classified with certainty as dentin?.
Differential diagnosis in the foregoing case prcwnted no major problems. The case history and clinical findings esclnded the possibi1it.y of osteitis. From the roentgenographic findings, it was fair]>- certain that the formation consisted of an odontogenic tumor. The small roentgenopaque granules in the roentgcnolncent area suggested that this was not a ITill soft-tissne tumor, such as an adamantinoma. Of the part,l,v n~inernlizctl tumors. the choice lay himen amelohlastic odontoma, soft odontoma with epitlielial niineralization,~ and possibly dentinoma. The differcnt,ial diagnosis bctneen thcsc tumors, which is of no real practical significance, had to be based on histologic examination.
An ameloblastic odontoma in a lO-~~~r-old girl \ras det,ected at a rwtint: school dental examination. The diagnosis ~vas made on the basis of roentgcnographic and histologic studies.
1. Clausen. F.: Cited bv E’indborlr.3 2. Frissell; C. T., and Skafer, \1c G.: Xmeloblastic z\h). 6 Odontoma., ORAL SURG., (k\I, ORAL PATH. 6: 1129, 1953. 3. Pindborg, J. J.: De Etrde tandraevs patologi, v-01. T. (‘o~wnhag~~n, 19;ii, Odontologisk Fortaning. 4. Silva, C. : Odontoameloblastoma, ORAL SURC., ORAL Mm. & ORAL PATII. 9: 545, 1956. 5. Thorns, IL H.: Oral Pathology, St. Louis, 1944, The C. \‘. Mosby Company. 6. Villa, V. G., and Bunag, C. ,4. : Calcification of the Epithelid Tissue Elements in Soft Msrd Odontoma, ORAL SURG., ORATEMm. & ORAL PATH. 9: 1218, 1056.