Large Unilocular Radiolucent Lesions of the Jaws: A Pathologist’sEnigma and a Surgeon’s Conundrum

Priya Jeyaraj*

Oral and Maxillofacial Surgery, Commanding Officer, Military Dental Centre (GoughLines), Secunderabad, Telangana, India

*Corresponding author: Colonel Priya Jeyaraj, MDS, Oral and Maxillofacial Surgery,Commanding Officer, Military Dental Centre (Gough Lines), Secunderabad, Telangana,

India, Tel: +919596840303; E-mail: jeyarajpriya@yahoo.com

Received date: March 18, 2019; Accepted date: April 16, 2019; Published date: April 23. 2019

Abstract

Unilocular radiolucent lesions of the jaws, inparticular, those which cause extensive destructionand hollowing out of the bone, are a major causefor concern, both, with regards to their correctdiagnosis, as well as a timely institution of the mostappropriate treatment procedure. A relativelyaggressive lesion with considerable invasive andrecurrence potential, such as an Odontogenictumor may radiologically and sometimes evenhistopathologically masquerade as a seeminglyinnocuous pathology such as an Odontogenic cyst.It is imperative to precisely diagnose andcompletely eliminate the lesion, while at the sametime, ensure least possible morbidity for thepatient, such as pathological fractures, persistingneurological deficits, esthetic deformity, functionaldebility, and of course, recurrence or persistence ofthe lesion. Histopathological examinationsupplemented by Immunohistochemical analysis ofbiopsy specimens, using Tumor Markers such asCalretinin and Prognostic Indicators such as Ki-67and Proliferating Cell Nuclear Antigen (PCNA), haveproved invaluable in correctly distinguishingbetween Odontogenic cysts and tumors andindicating their likely prognosis, thereby aiding intheir correct management.

Keywords:

Immunohistochemistry; Unicystic lesions;Dentigerous cysts; Unicystic ameloblastoma; Ki-67;

Proliferating cell nuclear antigen; Proliferationindex; Labelling index

Introduction

The most common cause of a large unilocular lyticlesion of the jaws is the Odontogenic cyst, andwhen seen in association with an impacted tooth, itis most likely to be a Dentigerous cyst [1]. This isthe most common non-inflammatory Odontogeniccyst which develops from the epithelial remnants ofthe dental follicle as a result of fluid accumulationbetween the follicular epithelium and crown of adeveloping or unerupted tooth.

Unless noticed on radiographs as an incidentalfinding, these cysts often remain undetected. Theyare capable of enlarging unobtrusively andasymptomatically, attaining quite large sizes,causing considerable hollowing out of the jaws. It isusually only when they are associated with pain,infection, inflammation or a visible bony expansion,that they are observed, investigated anddiagnosed. A cause of concern is that these cystsmay also transform into an Odontogenic tumorsuch as Ameloblastoma and its variants [2], or eveninto Mucoepidermoid carcinoma [3] or Squamouscell carcinoma. Accurate and precise diagnosis iscrucial in order to institute the correct surgicaltreatment modality and manage the pathologyadequately.

When Odontogenic tumors present as a Unilocularradiolucency, they exhibit marked similarities to the

Case Report Volume 9 Issue 3: 185 2019ISSN: 2250-0359

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Odontogenic cysts, with even overlappinghistological features. However, they varyconsiderably from the cysts in their biologicalbehavior, in terms of invasiveness, aggressiveness,tendency for local destruction, recurrence andmalignant transformation; and hence require vastlydifferent therapies and treatment modalities fromthe former [4]. In this way, what may appear as aninnocuous Unicystic lesion, mimicking anOdontogenic cyst, may in fact be an aggressive anddestructive tumor, adding to its enigma anddiagnostic dilemma for the Oral pathologist and aconundrum for the Maxillofacial surgeon as to itsmost appropriate and ideal management modality[5].

Case Report

A 23-year-old male patient reported with thecomplaint of a swelling on the left side of the face inthe region of the lower jaw, for the past five months,which over the past three days, had beenaccompanied by a dull, deep seated pain in theregion. Clinical examination showed a diffuse, firmand tender swelling in the region of the left angleand ramus of the mandible, extending below toinvolve the inferior border of the mandible, andabove, almost up to the Temporomandibular jointregion. On intraoral examination, all three left lowermolar teeth were missing and the alveolar mucosain the region appeared swollen and inflamed. Therewas no sinus opening or purulent discharge notedintra- or extra orally. There was mild regionallymphadenopathy, and the patient was mildlyfebrile (Figure 1).

History revealed that he had been operated for alarge cystic lesion of the left mandibular angle andbody, 11 years ago. Case records revealed that amarsupialization procedure had been carried outwhen he was a 12-year-old child, and the left lowerfirst and second molar teeth had been removedduring the same surgical procedure, however, thethird molar tooth germ had been left in situ. Thereason given by the then treating surgeon was thatthe bone of the mandible had been excessivelyhollowed out and was extremely weak, vulnerableand liable to fracture had removal of the third molaror enucleating of the entire lesion had beenattempted in the young child.

Figure 1: (A-D) 23-y-old male patient who reported with complaintsof pain and swelling in the region of left angle of mandible. Onintraoral examination, all three molars were missing on the left side.(E) OPG taken at 3 year ago, showing no evidence of the radiolucentlesion at that time, but revealing the presence of an impactedmandibular third molar in the region. (F-R) Present Radiographsrevealed an extensive unilocular radiolucency involving the left angleand ramus of the mandible extending posteriorly almost up to the tipof the coronoid process. A horizontally impacted third molar laywithin the radiolucent space. (S-U) Histopathological examination ofan incisional biopsy revealed features of a Dentigerous cyst with ahyperplastic epithelium. (V, W) IH examination revealed positiveexpression of Calretinin by the epithelial cells lining the cyst forminga brownish band-like appearance. This was suggestive of a UnicysticAmeloblastoma with no luminal or mural proliferation of the tumorcells. (X, Y) There was positive Ki-67 expression by few of the basalcells of the epithelial lining of the cyst. The Ki-67 Labelling Index wasvery low LI=0.9, indicating a tumor of insignificant aggressive orinvasive potential. (Z) PCNA labelling index was low as well LI=0.5.

The patient had been reviewed for a year, but hadnot been taken up for surgical enucleation of theremaining pathology and the remnant cyst lining.The patient had thereafter not reported back for

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follow up until three years ago, when anorthopantomogram had been taken. It did notreveal any obvious pathology or lesion within thebone, other than the horizontally impacted 38 lyingin the angle region of the mandible (Figure 1).

An Orthopantomogram was taken which revealed alarge radiolucency involving the left angle and ramusof the mandible extending posteriorly almost up tothe tip of the coronoid process and anteriorly up tothe missing first molar region. A horizontallyimpacted third molar lay within the radiolucentspace. Non Contrast Computed Tomographic Scans(NCCT) of the maxillofacial region showed extensivedestruction and hollowing out of the bone in theregion of the angle and ramus on the left side withbuccal as well as lingual cortical perforation noted atvarious locations. On corroborating the clinical andradiographic findings with the history, a provisionaldiagnosis of a persisting and progressing cysticlesion of the left mandibular angle and ramus, mostlikely, a Dentigerous cyst in relation to the impactedmandibular third molar tooth, with secondaryinfection, was made. Differential diagnosis includedodontogenic tumors such as Ameloblastoma orKeratocystic Odontogenic Tumor (KCOT) (Figure 2).

Figure 2: Non Contrast Computed Tomographic Scans (NCCT) of themaxillofacial region with 3-Dimensional reformatting, showing theextensive hollowing out and destruction of the left angle and ramusof mandible caused by the pathology. A displaced and impacted thirdmolar tooth was evident within the lesion.

The patient was put on Oral Antibiotics and Anti-inflammatory medication for five days, to which he

responded very well with a complete resolution ofthe pain and reduction in size of the swelling. Anincisional biopsy was carried out removing a smallwindow of bone through the buccal cortical plate.Histopathological examination of the tissue samplerevealed features of a dentigerous cyst with ahyperplastic epithelium. Immunohistochemicalexamination revealed positive expression ofCalretinin by the epithelial cells lining the cyst,forming a brownish band-like appearance. This wassuggestive of a unicystic Ameloblastoma with noluminal or mural proliferation of the tumor cells.There was positive Ki-67 expression by few of thebasal cells of the epithelial lining of the cyst. TheKi-67 Labelling Index was very low LI=0.9, indicatinga tumor of mild aggressive or invasive potential.PCNA labelling index was low as well LI=0.5.

Figure 3: ( AA’-AF’) Enucleation and curettage of the lesion carriedout, along with removal of the impacted third molar tooth. (AG’) Thiswas followed by Chemical cauterization of the walls of the bonycavity with Carnoy’s solution, taking care to protect the neighboringtissues from the highly caustic substance. (AH’ –AL’) Fresh autologousPlatelet Rich Fibrin harvested from the patient, was placed within theresidual cavity to encourage subsequent bone fill and promotequicker reossification of the bone defect. This was followed bywatertight closure of the mucoperiosteal flap (AM’-AT’)Postoperative NCCT.

The patient was taken up for Enucleation andCurettage of the cystic lesion of the left angle andramus of the mandible via an intraoral approach,removal of the horizontally impacted third molar

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tooth lying within the lesion, and peripheralostectomy of the residual bony walls. This wasfollowed by chemical cauterization of the walls ofthe bone defect using Carnoy’s solution, in order tocompletely eliminate any persisting or residualtumor cells in the vicinity. Autologous Platelet RichFibrin was then placed within the bony cavity toaccelerate both soft tissue healing in the operatedsite as well encourage and hasten bone fill with theresidual large bony defect of the mandible, so as tofacilitate an early rehabilitation of the young patientsubsequently with dental prostheses for the missingmolar teeth (Figure 3).

Discussion

The importance and value of the correct diagnosisas well as an indication of the likely prognosis of adestructive jaw lesion cannot be stresses enough.Immunohistochemistry is of immense value, both,as a diagnostic indicator as well as a prognosticindicator, guiding the ideal management protocol tobe employed, on a case to case basis [6].

Enucleation is the procedure of choice for removalof most cysts and other benign pathology of the oraland maxillofacial region, and involves completeremoval of the entity. It is suitable for thosepathologies which are surrounded by a capsule thatis anatomically distinct and cleaves easily from thesurrounding tissue, and is thus amenable to thistype of therapy. Physical or chemical curettage maybe added to the enucleation procedure in certainpathologies that require additional removal ofsurrounding bone suspected to have microscopicinvaginations of the lesion or satellite cysts/tumours, to help ensure their complete removal andto decrease the persistence and recurrence of thelesion [7]. Curettage may be completed with a sharpcurette or a round diamond/tungsten carbide burwith copious cool irrigation to remove 1 to 2 mm ofbone containing any pathology remnants.

Meticulous technique in the procedure ofenucleation and curettage is particularly importantin the surgical management of lesions that tend tohave high recurrence or persistence rates, in whichcase, the addition of Carnoy’s solution to curettageor peripheral ostectomy has been shown to be evenmore effective in decreasing the recurrence ratethan are the enucleation procedures alone [8]. This

procedure was employed, in this case ofDentigerous cyst showing histopathologicalevidence of ameloblastomatous change, which bymeans of corroborating the histopathological as wellas Immunohistochemical findings, was preciselydiagnosed as Unicystic Ameloblastoma of theluminal subtype.

Immunohistochemical analysis helped in diagnosingthe presence of Ameloblastoma by means of thepositive expression of Calretinin which is a tumormarker specific for Ameloblastoma and its variants[9]. This diagnosis could have been missed entirely,had histopathological examination alone been reliedupon. Further, the low Labelling Index of theImmunohistochemical Proliferative Markers (Ki-67and PCNA) [10], also helped prevent overtreatmentin the form of Jaw resection in this young patient.Institution of additional measures in terms of avigorous and thorough curettage with peripheralostectomy of a 5 mm margin of bone all along theperiphery of the lesion, in addition to chemicalcauterization of the bony walls of the residual defectto destroy any remnant tumor cells, would helpprevent future recurrence of the lesion.

The enucleation and curettage procedure is limitedin the treatment of multicystic lesions [11] for whichthe treatment of choice might otherwise be theUnicystic counterpart [12]. Benign multicysticlesions of the oral and maxillofacial region may havenumerous loculations and invaginations that wouldmake access extremely difficult using even anextraoral approach and almost impossible if using anintraoral approach. In addition, the enucleationprocess may not remove the pathology in itsentirety, and physical and chemical curettage maynot be able to access or remove all remnants of thelesion. This will invariably lead to persistence of thelesion, particularly a high-recurrence lesion like theKeratocystic Odontogenic Tumor, or in aggressivebenign lesions such as the Solid/ MulticysticAmeloblastoma [13].

Conclusion

In cases of extensive Unilocular lesions of the jaws,where ambiguity often exists in both diagnosis andappropriate treatment plan, Immunohistochemistrycan serve as an invaluable tool in establishing theprecise diagnosis, guiding the treatment plan, as

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well as indicating the likely prognosis of theselesions. Thus, it is of utmost importance to correlatehistopathologic findings with clinical andradiographic features as well asImmunohistochemical analysis, to arrive at a correctdefinitive diagnosis as all such lesions may haveprognostically different biologic behaviors and thefinal diagnosis may alter the therapeutic decisionsignificantly.

Compliance with Ethical Standards

Disclosure of potential conflicts of interest

The author of this article has not received anyresearch grant, remuneration, or speakerhonorarium from any company or committeewhatsoever, and neither owns any stock in anycompany. The author declares that she does nothave any conflict of interest.

Research involving human participants and/or animals

All procedures performed on the patients (humanparticipants) involved were in accordance with theethical standards of the institution and/or nationalresearch committee, as well as with the 1964Helsinki declaration and its later amendments andcomparable ethical standards.

Ethical Approval

This article does not contain any new studies withhuman participants or animals performed by theauthor.

Informed Consent

Informed consent was obtained from all theindividual participants in this study.

Funding

This study was not funded by any organization/society.

References

1. Freitas DQ, Tempest LM, Sicoli E, et al. Bilateraldentigerous cysts: Review of the literature and report ofan unusual case. Dentomaxillofac Radiol. 2006;35:46448.

2. Rosenstein T, Pogrel MA, Smith RA, et al. Cysticameloblastoma-Behaviour and treatment of 21 cases. JOral Maxillofac Surg. 2001;59:1311-16.

3. Gulbranson SH, Wolfrey JD, Raines JM, et al. Squamouscell carcinoma arising in a dentigerous cyst in a16monthold girl. Otolaryngol Head Neck Surg.2002;127:46364.

4. Scariot R, da Silva RV, da Silva Felix Jr W, et al. Conservativetreatment of ameloblastoma in child: A case report.Stomatologija. 2012;14: 33-6.

5. Chapelle KA, Stoelinga PJ, Wilde PC, et al. Rationalapproach to diagnosis and treatment of ameloblastomasand odontogenic keratocysts. Br J Oral Maxillofac Surg.2004;42:381-90.

6. Goncalves CK, Fregnani ER, Leon JE, et al.Immunohistochemical expression of p63, epidermalgrowth factor receptor (EGFR) and notch-1 in radicularcysts, dentigerous cysts and Keratocystic odontogenictumors. Braz Dent J. 2012;23:337-43.

7. Ramesh RS, Manjunath S, Ustad TH, et al. Unicysticameloblastoma of the mandible-An unusual case reportand review of literature. Head Neck Oncol. 2010;14:2-7.

8. Lee PK, Samman N. Unicystic ameloblastoma- Use ofCarnoy’s solution after enucleation Int. J Oral MaxillofacSurg. 2004;33:263-67.

9. De Villiers P, Liu H, Suggs C, et al. Calretinin expression inthe differential diagnosis of human ameloblastoma andkeratocystic odontogenic tumor. Am J SurgPathol. 2008;32:256-60.

10. Piattelli A, Fioroni M, Santinelli A, et al. Expression ofproliferating cell nuclear antigen in ameloblastomas andodontogenic cysts. Oral Oncology. 1998;34:408-12.

11. Pogrel MA, Montes DM. Is there a role for enucleation inthe management of ameloblastoma? Int J Oral MaxillofacSurg. 2009;38:80712.

12. Navarro CM, Principi SM, Massucato EM, et al. Maxillaryunicystic ameloblastoma. DentomaxillofacRadiol. 2004;331:60-2.

13. Nakamura N, Higuchi Y, Mitsuyasu T, et al. Comparison oflong term result between different approaches ofameloblastoma. Oral Surg Oral Med Oral Pathol OralRadiol Endod. 2002;93:13-20.

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