diagnostics Case Report Dentigerous Cysts with Diverse Radiological Presentation Highlighting Diagnostic Challenges Alexandre Perez 1, * , Vincent Lenoir 2 1 2 3 * and Tommaso Lombardi 3 Unit of Oral Surgery and Implantology, Division of Oral and Maxillofacial Surgery, Department of Surgery, University of Geneva & University Hospitals of Geneva, 1205 Geneva, Switzerland Division of Radiology, Diagnostic Department, Geneva University Hospitals, University of Geneva, 1205 Geneva, Switzerland Unit of Oral Medicine and Oral Maxillofacial Pathology, Division of Oral and Maxillofacial Surgery, Department of Surgery, University of Geneva & University Hospitals of Geneva, 1205 Geneva, Switzerland Correspondence: [email protected] Abstract: Dentigerous cyst is an odontogenic developmental cyst arising from the pericoronal tissue of an impacted tooth, and that may exhibit various radiological aspects. The aim of this article is to present four cases of histologically confirmed mandibular dentigerous cysts to highlight diverse radiological presentations: one of classical appearance (well-limited unilocular radiolucent lesion surrounding the crown) and three which have shown radiological peculiarities (one cyst displacing the adjacent tooth, with bone but no root resorption, one cyst presenting hallmarks of infection and one multilocular cyst with thin septa). Such radiologic diversity may, on occasion, suggest a clinical aggressive lesion such as an odontogenic keratocyst or ameloblastoma. The diagnosis of dentigerous cyst requires a thorough evaluation of the clinical presentation and accurate radiological studies. Keywords: odontogenic cysts; dentigerous cyst; jaws; oral surgery; oral pathology; imaging; OPG; CBCT Citation: Perez, A.; Lenoir, V.; Lombardi, T. Dentigerous Cysts with Diverse Radiological Presentation Highlighting Diagnostic Challenges. 1. Introduction Diagnostics 2022, 12, 2006. https:// A dentigerous cyst (DC), also known as a follicular cyst, is a cyst of non-inflammatory odontogenic origin that develops from the pericoronal tissue (dental sac or dental follicle) of an impacted tooth, either permanent or deciduous or supernumerary [1–6]. Several factors have been investigated and are known to play an important role in tooth eruption [7]. DCs represent more than 24% of the cysts of the maxilla [8–10]. Their incidence peaks in the third decade of life (21–30 years), followed by a gradual decrease with age. It is also slightly higher in men (sex ratio 1.5 man/L female) [2,4] and is not influenced by ethnicity [8,10]. Furthermore, 2.5 to 4% of patients with an impacted tooth develop a DC [4,8], of which 95% are associated with a permanent tooth and 5% with a supernumerary tooth [2,11,12]. Regarding localization, 74% of DCs localize in the mandible and 26% in the maxilla with a symmetrical left/right distribution [13–16]. Bilateral lesions are extremely rare, and when occurring, association with development anomalies and syndromes, such as mucopolysaccharidosis or cleidocranial dysplasia, should be suspected [1,2,5]. Clinically, DCs are often asymptomatic but may occasionally cause swelling and dental displacement [8,9,14,15]. More rarely, a DC may be accompanied by pain caused by superposed infection or paresthesia when mechanical compression on a nerve occurs [11]. DCs are most often diagnosed incidentally during an oral check-up, and the panoramic dental X-ray (OPG) is generally the most frequent diagnostic imaging technique carried out. Radiologically, DCs usually appear as well-defined unilocular radiotransparent homogeneous lesions with a round or ovoid shape attached to the cementoenamel junction of an impacted tooth, usually third molars, and largely in the mandible [9,11,12]. doi.org/10.3390/diagnostics 12082006 Academic Editors: Luca Testarelli and Shankargouda Patil Received: 25 July 2022 Accepted: 16 August 2022 Published: 19 August 2022 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). Diagnostics 2022, 12, 2006. https://doi.org/10.3390/diagnostics12082006 https://www.mdpi.com/journal/diagnostics Diagnostics 2022, 12, 2006 ried out. Radiologically, DCs usually appear as well-defined unilocular radiotransparent homogeneous lesions with a round or ovoid shape attached to the cementoenamel junction of an impacted tooth, usually third molars, and largely in the mandible [9,11,12]. The borders of the lesion may appear sclerotic and are less well-defined when2 of the 14 cyst becomes infected. When the cyst is large, it may displace or even resorb adjacent dental roots or may induce bone remodelling. However, the bone cortex usually remains intact. Thethis borders of the may appear are less well-defined the cyst In article, we lesion present four casessclerotic of DC and to highlight the diversewhen radiological becomes infected. When the cyst is large, it may displace or even resorb adjacent dental presentation: one of classical appearance (case #2) and three which have shown radiologroots or may induce bone remodelling. However, the bone cortex usually remains intact. ical peculiarities (case #1, cyst displacing the adjacent tooth, with bone but no root resorpIn this article, we present four cases of DC to highlight the diverse radiological tion; case #3, cyst presenting hallmarks of infection; case #4, multilocular cyst with thin presentation: one of classical appearance (case #2) and three which have shown radiological septa). peculiarities (case #1, cyst displacing the adjacent tooth, with bone but no root resorption; case #3, cyst presenting hallmarks of infection; case #4, multilocular cyst with thin septa). 2. Case Series All Series the cases presented refer to lower third molars. 2. Case Case #1:cases presented refer to lower third molars. All the A 30-year-old male in good general health consulted the Oral Surgery and ImplanCase #1: tologyAUnit of the Geneva Hospitals for pain experienced for two local30-year-old male in University good general health consulted the Oral Surgery anddays Implantolized in the quadrant of Hospitals the mandible, withexperienced no fever nor and throat ogy Unit ofleft the lower Geneva University for pain forear, twonose, days localized in symptoms. the left lower quadrant of the mandible, with no fever nor ear, nose, and throat symptoms. On On extraoral extraoral examination, examination, palpation palpation at at the the angle angle and and the the horizontal horizontal branch branch of of the the mandible was painful, and so was intraoral palpation at the vestibular level from tooth mandible was painful, and so was intraoral palpation at the vestibular level from tooth #37 #37 to the ascending branch of the mandible. to the left left ascending branch of the mandible. On On dental dental examination, examination, tooth tooth #37 #37 showed showed sensibility sensibility positive positive test, test, slightly slightly painful painful percussion, of of more than 9 mm localized distally andand aspercussion, and andaapocket pocketdepth depthononprobing probing more than 9 mm localized distally sociated with suppuration. associated with suppuration. Panoramic Panoramic radiography radiography revealed revealed the the presence presence of of aa pericoronal pericoronal radiolucent radiolucent lesion lesion around the crown of an impacted tooth #38 (horizontally positioned with mesial orientaaround crown of an impacted tooth #38 (horizontally positioned with mesial orientation) tion) (Figure 1).lesion The lesion measuring 27mm × 22was mmwell wasdefined well defined and unilocular, sur(Figure 1). The measuring 27 × 22 and unilocular, surrounded rounded a thin bone. sclerotic bone. It overlapped distal root #37, of tooth #37, adjacent causing by a thinby sclerotic It overlapped with the with distalthe root of tooth causing adjacent bone resorption root resorption. Theseemed cyst seemed to interfere bone resorption but withbut nowith signsnoofsigns root of resorption. The cyst to interfere with the inferior alveolar canalcanal (IAC), which appeared displaced caudally by by thethe lesion. A with the inferior alveolar (IAC), which appeared displaced caudally lesion. presumptive diagnosis of of CD was made. A presumptive diagnosis CD was made. Figure 1. Panoramic X-ray of case #1. An additional cone-beam computed tomography (CBCT) X-ray examination confirmed the presence of the large pericoronal cystic lesion attached to the cementoenamel junction of tooth #38 (Figure 2). We observed a bone expansion accompanied by slight thinning of the mandibular cortex on the vestibular and lingual sides. The cyst was in contact with the upper wall of the IAC, which was thinned and caudally displaced, but of normal width. This lesion had an approximately 8 mm opening on the mucosal alveolar crest and extended to the distal root of tooth #37 without signs of associated root resorption. Diagnostics 2022, 12, 2006 firmed the presence of the large pericoronal cystic lesion attached to the cementoenamel junction of tooth #38 (Figure 2). We observed a bone expansion accompanied by slight thinning of the mandibular cortex on the vestibular and lingual sides. The cyst was in contact with the upper wall of the IAC, which was thinned and caudally displaced, but of normal width. This lesion had an approximately 8 mm opening on the mucosal alveolar 3 of 14 crest and extended to the distal root of tooth #37 without signs of associated root resorption. Figure Figure2.2.CBCT CBCTX-ray X-rayofofcase case#1. #1. There periosteal reaction, pathological fracture, evident signssigns of sequesTherewas wasalso alsonono periosteal reaction, pathological fracture, evident of sequestration or sclerosis the surrounding nor infiltration the perimandibular tration or sclerosis of theofsurrounding bone,bone, nor infiltration of theofperimandibular soft soft tissues. #38two had two and roots, the mesial rootinto came into contact the tissues. Tooth Tooth #38 had roots, theand mesial root came contact with thewith lingual lingual wall of the The radiological appearance a DC. Differential wall of the IAC. TheIAC. radiological appearance evoked aevoked DC. Differential diagnosesdiaginnoses included odontogenic andameloblastoma. unicystic ameloblastoma. Theenucleated lesion was cluded odontogenic keratocystkeratocyst and unicystic The lesion was in toto tooth under local of DC inenucleated toto together withtogether tooth #38with under local#38 anesthesia. Theanesthesia. diagnosis ofThe DCdiagnosis was confirmed was confirmed by histopathological examination (Figure 3).followed The patient wasyears. followed by histopathological examination (Figure 3). The patient was for four At for four years. At 12 months follow-up, OPG showed satisfactory healing of the enucle12 months follow-up, OPG showed satisfactory healing of the enucleation cavity and tooth 4 of 16 Diagnostics 2022, 12, x FOR PEER REVIEW ation cavity and tooth #37 vitalwas (Figure 4). The patient waswith followed-up #37 was still vital (Figure 4).was Thestill patient followed-up for 4 years no signs for of 4 years with no signs of recurrence. recurrence. Figure 3. 3.Histopathological of the theenucleated enucleated specimen from #1 showing an Figure Histopathologicalexamination examination of specimen from case case #1 showing an uninflamed fibrous cyst wall lined by a thin cuboidal epithelial lining (H&E, ×40). uninflamed fibrous cyst wall lined by a thin cuboidal epithelial lining (H&E, ×40). Diagnostics 2022, 12, 2006 4 of 14 Figure 3. Histopathological examination of the enucleated specimen from case #1 showing an uninflamed fibrous cyst wall lined by a thin cuboidal epithelial lining (H&E, ×40). Figure 4. Panoramic X-ray of case #1 at one-year follow-up. Figure 4. Panoramic X-ray of case #1 at one-year follow-up. Case #2: #2: Case A 38-year-old female referred byby herher orthodontist for for diA female in ingood goodgeneral generalhealth healthwas was referred orthodontist agnosis and treatment of a lesion in the right lower quadrant of the mandible discovered diagnosis and treatment of a lesion in the right lower quadrant of the mandible discovincidentally on anon OPG X-rayX-ray performed prior to orthodontic treatment. The oral examiered incidentally an OPG performed prior to orthodontic treatment. The oral nation was unremarkable, and the patient was asymptomatic. examination was unremarkable, and the patient was asymptomatic. Diagnostics 2022, 12, x FOR PEER REVIEW 5 of 15 A new new OPG OPG X-ray X-ray revealed revealed the the presence presence of of aa pericoronal pericoronal radiolucent radiolucent lesion lesion on on an A an impactedtooth tooth#48, #48,which whichwas wasinverted inverted mesio-caudal direction (Figure 5). The leimpacted inin thethe mesio-caudal direction (Figure 5). The lesion sionwell was defined, well defined, measured 13mm, × 15and mm,was and was surrounded bysclerotic a thin sclerotic was measured 13 × 15 surrounded by a thin border border overlapping the distal root of tooth #47, which appeared slightly resorbed. overlapping with thewith distal root of tooth #47, which appeared slightly resorbed. The cyst also with the IAC, walls couldwalls not have during this The overlapped cyst also overlapped withwhose the IAC, whose couldbeen not well-identified have been well-identified exam. diagnosis was a DC. was a DC. duringThe thispresumptive exam. The presumptive diagnosis Figure 5. Panoramic X-ray of case #2. Figure 5. Panoramic X-ray of case #2. On the the complementary complementaryCBCT CBCTX-ray, X-ray,it it was observed impacted tooth in horiOn was observed anan impacted tooth #48#48 in horizonzontal/inverted orientation in mesio-caudal the mesio-caudal direction (Figure 6).two Theroots two were rootsnot were tal/inverted orientation in the direction (Figure 6). The in not in direct contact with the right IAC, and the tooth crown did not come into direct direct contact with the right IAC, and the tooth crown did not come into direct contact with contact the #47. root The of tooth #47. Thespace pericoronal space was markedly enlarged, 13 mm the root with of tooth pericoronal was markedly enlarged, 13 mm wide, 17 wide, 17 mm high, and 15 mm long, compatible with a DC. The visible resorption of the distal root of tooth 47 made a differential diagnosis of odontogenic keratocyst less likely. The lesion was associated with an alveolar crest dehiscence of over 4 mm in length and thinned lingual cortex. The lesion displaced the IAC caudally, causing loss of visibility of Figure 5. Panoramic X-ray of case #2. Diagnostics 2022, 12, 2006 On the complementary CBCT X-ray, it was observed an impacted tooth #48 in horizontal/inverted orientation in the mesio-caudal direction (Figure 6). The two roots were 5 of 14 not in direct contact with the right IAC, and the tooth crown did not come into direct contact with the root of tooth #47. The pericoronal space was markedly enlarged, 13 mm wide, 17 mm high, and 15 mm long, compatible with a DC. The visible resorption of the distal 47 made a differential of odontogenic keratocyst less likely. high, root and of 15 tooth mm long, compatible with adiagnosis DC. The visible resorption of the distal root of The lesion was aassociated an alveolar crest dehiscence of over 4 mm The in length tooth 47 made differentialwith diagnosis of odontogenic keratocyst less likely. lesionand was associated withcortex. an alveolar crest dehiscence of IAC overcaudally, 4 mm in length lingual thinned lingual The lesion displaced the causingand lossthinned of visibility of cortex. its wall. The lesion displaced the IAC caudally, causing loss of visibility of its wall. Figure Figure6.6.CBCT CBCTX-ray X-rayof ofcase case#2. #2. Teeth 4848 were extracted, andand the the pericoronal lesion in tooth #38 was Teeth #18, #18,28, 28,3838and and were extracted, pericoronal lesion in tooth #38 enucleated in totoinunder local anesthesia. The diagnosis of DC of was confirmed by histowas enucleated toto under local anesthesia. The diagnosis DC was confirmed by pathological examination. The patient was followed-up for two years. At 12 of histopathological examination. The patient was followed-up for two years. Atmonths 12 months Diagnostics 2022, 12, x FOR PEER REVIEW 6 of 15 control, an an intraoral X-ray showed good healing ofofthe of control, intraoral X-ray showed good healing theenucleation enucleationcavity cavityofofthe thefollicular follicular cyst(Figure (Figure7). 7).Clinically, Clinically, tooth tooth #47 #47 remained remained vital vital and and asymptomatic. asymptomatic. cyst Figure7.7.Intraoral IntraoralX-ray X-rayofofcase case#2 #2atatone-year one-yearfollow-up follow-upexam. exam. Figure Case#3: #3: Case A 46-year-old femalein ingood goodgeneral generalhealth healthconsulted consultedthe theOral OralSurgery Surgeryand andImplanImplanA 46-year-old female tology Unit of the Geneva University Hospitals for the management of a lesion in theleft left tology Unit of the Geneva University Hospitals for the management of a lesion in the lowerquadrant quadrantofofthe the mandible discovered fortuitously on OPG an OPG X-ray performed by lower mandible discovered fortuitously on an X-ray performed by her her dentist. The patient a history of episodic this area over several dentist. The patient had ahad history of episodic pain inpain this in area over several months,months, which which she intermittently treated intermittently with self-medicated painkillers and anti-inflammatory she treated with self-medicated painkillers and anti-inflammatory drugs. drugs. The oral clinical examination was unremarkable, and the patient was asymptomatic. The oral aclinical examination was unremarkable, the patient wastooth asymptomatic. On the OPG, pericoronary radio-transparent lesionand around impacted #38 was discovered (Figure 8). The involved tooth was lesion oriented mesially. The lesion poorly On the OPG, a pericoronary radio-transparent around impacted tooth was #38 was disdelimited, measured 24 ×involved 10 mm, and stretched to the apparently resorbed root apex covered (Figure 8). The tooth was oriented mesially. The lesiondistal was poorly deoflimited, tooth #37. The roots overlapped with the IAC, raising suspicion of measured 24 ×of10tooth mm,#38 andclearly stretched to the apparently resorbed distal root apex interference. of a DC with infectionof of tooth #37.The TheOPG rootsimages of toothwere #38 indicative clearly overlapped withpossible the IAC,secondary raising suspicion and perilesional sclerosing osteitis. interference. The OPG images were indicative of a DC with possible secondary infection and perilesional sclerosing osteitis. Diagnostics 2022, 12, 2006 The oral clinical examination was unremarkable, and the patient was asymptomatic. On the OPG, a pericoronary radio-transparent lesion around impacted tooth #38 was discovered (Figure 8). The involved tooth was oriented mesially. The lesion was poorly delimited, measured 24 × 10 mm, and stretched to the apparently resorbed distal root apex of tooth #37. The roots of tooth #38 clearly overlapped with the IAC, raising suspicion 6 of of 14 interference. The OPG images were indicative of a DC with possible secondary infection and perilesional sclerosing osteitis. Figure 8. Panoramic X-ray of case #3. Figure 8. Panoramic X-ray of case #3. The complementary CBCT examination found that tooth #38 was directed mesially The complementary CBCT examination found that tooth #38 was directed mesially and slightly lingually (Figure 9) and that it had three roots, with the deformed IAC tortuand slightly lingually (Figure 9) and that it had three roots, with the deformed IAC torously passaging between them. The crown of tooth #38 was close to the distal root of7tooth Diagnostics 2022, 12, x FOR PEER REVIEW of 15 tuously passaging between them. The crown of tooth #38 was close to the distal root of #37, whose apex was strongly resorbed. The pericoronal osteolytic lesion measuring 24 × tooth #37, whose apex was strongly resorbed. The pericoronal osteolytic lesion measuring 10 × 10 from the crown-root junction of tooth to #38 the to partially resorbed 24 × 10mm × 10extended mm extended from the crown-root junction of #38 tooth the partially resorbed distal root of tooth #37.was There was bone dehiscence of on 12 the mmalveolar on the alveolar crest distal root of tooth #37. There bone dehiscence of 12 mm crest and of and of 5 mm on the vestibular cortex. The borders of the lesion were in places irregular 5 mm on the vestibular cortex. The borders of the lesion were in places irregular and and strongly sclerotic, indicating a superimposed infection. no signs of bone strongly sclerotic, indicating a superimposed infection. ThereThere werewere no signs of bone sesequestration, periosteal reaction or associated fracture. findings supported the questration, periosteal reaction or associated fracture. TheseThese findings supported the initial initial diagnosis of DC. diagnosis of DC. Figure Figure9.9.CBCT CBCTX-ray X-rayof ofthe thecase case#3 #3patient. patient. Teeth Teeth #37, #37, 38 38 and and 48 48 were were extracted extracted under under local local anesthesia. anesthesia. The Thelesion lesionon on tooth tooth #38 #38 was wassubmitted submitted for for histopathological histopathological examination, examination, which which confirmed confirmed the diagnosis of DC. Case#4: #4: Case A 59-year-old 59-year-oldmale malewas wasreferred referredto to the the Oral Oral Surgery Surgery and and Implantology ImplantologyUnit Unitof ofthe the A GenevaUniversity UniversityHospitals Hospitalsfor foraacomprehensive comprehensiveoral oralexamination examinationand anddental dentalcare careprior prior Geneva to the the start start of of radioradio- and and chemotherapy chemotherapyfor forsquamous squamouscell cellcarcinoma carcinomaof ofthe thefloor floorof of the the to ® for epilepsy, Beloc ZOC®® and Atacand®® for high ® mouth. The patient was taking Rivotril mouth. The patient was taking Rivotril for epilepsy, Beloc and Atacand for high bloodpressure pressureand andCrestor Crestor®®for forhyperlipidemia. hyperlipidemia.He Hewas wasaaheavy heavysmoker smoker(70 (70pack packyear) year) blood andconsumed consumed60 60ggof ofalcohol alcoholaa day. day. and The extraoral clinical examination was unremarkable. Intraorally, the mucosa of the hard and soft palate as well as the lingual mucosa showed keratotic dots; on the floor of the mouth, there was a 3 cm long and 1 cm wide ulceration; the oral vestibule presented a smoker keratosis. Oral hygiene was poor with plaque and tartar deposits; the patient Diagnostics 2022, 12, 2006 7 of 14 The extraoral clinical examination was unremarkable. Intraorally, the mucosa of the hard and soft palate as well as the lingual mucosa showed keratotic dots; on the floor of the mouth, there was a 3 cm long and 1 cm wide ulceration; the oral vestibule presented a smoker keratosis. Oral hygiene was poor with plaque and tartar deposits; the patient had severe periodontal disease with grade III furcation involvement of teeth #46, 26 and 16, polycaries of teeth #16, 14, 13, 12, 23, 25, 46, 45, 43, 42, 41, 32, 33, 34 and 35; teeth #15, 14, 11, 22, 27, 47, 36 and 37 were absent. On an OPG X-ray, teeth #38 and 48 were impacted and distally orientated (Figure 10). Tooth #38 showed a radiotransparent lesion measuring 20 × 15 mm, with a well-defined Diagnostics 2022, 12, x FOR PEER REVIEW 8 of 15 border, multilocular appearance, and a thin septum, most compatible with a DC versus ameloblastoma versus odontogenic keratocyst. Figure 10. OPG X-ray of case #4. Figure 10. OPG X-ray of case #4. On CBCT X-ray, X-ray,the thedistal distal root of the impacted tooth #38 in was in contact with the On CBCT root of the impacted tooth #38 was contact with the upper upper wall of the left IAC, generating a discreet deformation of the canal (Figure 11). The wall of the left IAC, generating a discreet deformation of the canal (Figure 11). The cyst cyst showing a multilocular was located adjacent to the of crown tooth and showing a multilocular aspectaspect was located adjacent to the crown toothof#38 and#38 seemed seemed to be attached to the tooth neck. Theextending lesion extending to the ascending to be attached to the tooth neck. The lesion slightly slightly to the ascending branch branch of the mandible measured in height, in length in width. of the mandible measured 17 mm17 in mm height, 21 mm21 inmm length and 10and mm10inmm width. In its In its caudal part, the was lesion in contact thewall upper wall of over the IAC over aboutThe 13 caudal part, the lesion in was contact with thewith upper of the IAC about 13 mm. mm. The wall was thinned but with little impact on its internal diameter. The vestibular wall was thinned but with little impact on its internal diameter. The vestibular and lingual and lingual were also strongly thinned focally. There was noreaction periosteal cortex were cortex also strongly thinned focally. There was no periosteal or reaction fracture or at fracture at the mandibular angle. Onofthe bases of these radiological thediagnosis differenthe mandibular angle. On the bases these radiological findings, thefindings, differential tial diagnosis DC, ameloblastoma, andkeratocyst. odontogenic keratocyst. included DC, included ameloblastoma, and odontogenic The lesion was enucleated in toto, and the teeth extracted (Figure 12) under general anesthesia, during which the ENT and maxillofacial surgeons proceeded with the placement of a mandibular osteosynthesis plate, followed by non-interruptive mandibulectomy, and finally, pelvi-glossectomy with tracheostomy and reconstruction with an anterolateral thigh flap and neck dissection. Histopathological examination of the cystic lesion allowed to diagnose a DC. The patient was followed regularly for two years, and no recurrence was observed. Diagnostics 2022, 12, 2006 seemed to be attached to the tooth neck. The lesion extending slightly to the ascending branch of the mandible measured 17 mm in height, 21 mm in length and 10 mm in width. In its caudal part, the lesion was in contact with the upper wall of the IAC over about 13 mm. The wall was thinned but with little impact on its internal diameter. The vestibular and lingual cortex were also strongly thinned focally. There was no periosteal reaction or 8 of 14 fracture at the mandibular angle. On the bases of these radiological findings, the differential diagnosis included DC, ameloblastoma, and odontogenic keratocyst. Diagnostics 2022, 12, x FOR PEER REVIEW 9 of 15 Diagnostics 2022, 12, x FOR PEER REVIEW 9 of 15 Figure 11. CBCT X-ray of case #4. The lesion was enucleated in toto, and the teeth extracted (Figure 12) under general anesthesia, during which the ENT and maxillofacial surgeons proceeded with the placement of a mandibular osteosynthesis plate, followed by non-interruptive mandibulectomy, and finally, pelvi-glossectomy with tracheostomy and reconstruction with an anterolateral thigh flap and neck dissection. Histopathological examination of the cystic lesion allowed to diagnose a DC. The patient was followed regularly for two years, and no Figure X-ray recurrence was observed. Figure11. 11.CBCT CBCT X-rayofofcase case#4. #4. The lesion was enucleated in toto, and the teeth extracted (Figure 12) under general anesthesia, during which the ENT and maxillofacial surgeons proceeded with the placement of a mandibular osteosynthesis plate, followed by non-interruptive mandibulectomy, and finally, pelvi-glossectomy with tracheostomy and reconstruction with an anterolateral thigh flap and neck dissection. Histopathological examination of the cystic lesion allowed to diagnose a DC. The patient was followed regularly for two years, and no recurrence was observed. Figure tooth 3838 and inin toto enucleation of of thethe cyst in in case #4.#4. Figure12. 12.Avulsion Avulsionofof tooth and toto enucleation cyst case Healing uneventful and thethe patient hadhad no complaints. Radiologically, at theat6-the Healingwas was uneventful and patient no complaints. Radiologically, and 12-month follow-up (Figure 13), 13), there waswas no no reossification at the cystectomy andand 6- and 12-month follow-up (Figure there reossification at the cystectomy tooth which could bebe explained byby a side effect of postoperative radiotherapy andand tooth3838sites, sites, which could explained a side effect of postoperative radiotherapy chemotherapy. there were nono signs of of enlargement of the residual bone cavity, chemotherapy.However, However, there were signs enlargement of the residual bone cavity, suggesting a recurrence of DC. suggesting a recurrence of DC. Figure 12. Avulsion of tooth 38 and in toto enucleation of the cyst in case #4. Healing was uneventful and the patient had no complaints. Radiologically, at the 6and 12-month follow-up (Figure 13), there was no reossification at the cystectomy and Diagnostics 2022, 12, x 2006 FOR PEER REVIEW Diagnostics 2022, 12, x FOR PEER REVIEW of 15 14 109 of 11 of 16 Figure13. 13.CBCT CBCT X-ray of Figure of case case44atatone oneyear yearfollow-up. follow-up. Figure 13. CBCT X-ray of case 4 at one year follow-up. Discussion 3. 3.3.Discussion Discussion DC is is the the second second most cyst occurring in association withwith an an DC common odontogenic cyst occurring in DC is the second most mostcommon commonodontogenic odontogenic cyst occurring in association association with an unerupted tooth. tooth. It It develops from the accumulation of of fluid between the the reduced enamel unerupted develops from the accumulation fluid between reduced enamel unerupted tooth. It develops from the accumulation of fluid between the reduced enamel epepithelium of of the the dental follicle and the ofof anan unerupted tooth (Figure 14). 14). The The epithelium dental follicle and thecrown crown unerupted tooth ithelium of the dental follicle and the crown of an unerupted tooth (Figure 14).(Figure The microscopic microscopic features of DC are dependent whether it is not inflamed or inflamed microscopic of DCwhether are dependent whetheroritinflamed is not [8,9,17,18]. inflamed or inflamed features of DCfeatures are dependent it is not inflamed In the case of [8,9,17,18]. In the case of non-inflamed DC, the epithelial lining is formed by two to four [8,9,17,18]. In DC, the case of non-inflamed DC, theby epithelial lining is formed by two to four non-inflamed the epithelial lining is formed two to four layers of cuboidal/squamous layers of cuboidal/squamous non-keratinizing cells without rete ridges and a flat layers of cuboidal/squamous without rete ridges and a flatinterface epithenon-keratinizing cells withoutnon-keratinizing rete ridges and acells flat epithelium-connective tissue epithelium-connective tissue interface (Figure 3). The cyst wall consists of fibrous or fibrolium-connective tissue cyst wall tissue consists of fibrous or fibro-myx(Figure The cyst wallinterface consists of(Figure fibrous3). orThe fibro-myxoid containing considerable myxoid3).tissue containing considerable glycosaminoglycan ground substance. Small glyoid tissue containing considerable glycosaminoglycan ground substance. Small islands cosaminoglycan ground substance. Small islands or cords of inactive-appearing odontogenic islands or cords of inactive-appearing odontogenic epithelial rests are usually present or cords inactive-appearing odontogenic epithelial rests are usually present within the epithelial rests are usually present within the connective tissue. withinofthe connective tissue. connective tissue. Figure 14. Dental follicle partly lined by reduced enamel epithelium (H&E, ×20). Diagnostics 2022, 12, x FOR PEER REVIEW 12 of 16 Diagnostics 2022, 12, 2006 10 of 14 Figure 14. Dental follicle partly lined by reduced enamel epithelium (H&E, ×20). of inflamed inflamed DC, DC, histopathologic histopathologic examination examination reveals reveals aa fibrous-connective fibrous-connective In the case of infiltration of chronic inflammatory inflammatory cells cells and, and, on on occasion, occasion, tissue wall with a variable infiltration lined in part or entirely by non-keratinizing squamous epithecholesterol clefts. clefts.The Thecyst cystis is lined in part or entirely by non-keratinizing squamous lium, which which shows shows varyingvarying amountsamounts of hyperplasia with the development of elongated epithelium, of hyperplasia with the development of and interconnected rete ridges. These features may lead to a misdiagnosis of radicular elongated and interconnected rete ridges. These features may lead to a misdiagnosis of cyst (Figure Mucus or, cells rarely, columnar cells may bemay observed in the radicular cyst15). (Figure 15).cells Mucus or,ciliated rarely, ciliated columnar cells be observed epithelial lining.lining. in the epithelial Figure 15. Non-keratinized Non-keratinizedspongiotic spongioticsquamous squamous epithelium presenting hyperplastic ridges. Figure 15. epithelium presenting hyperplastic reterete ridges. The The fibrous wall contains a lymphoplasmocytic infiltrate (H&E, ×10). fibrous wall contains a lymphoplasmocytic infiltrate (H&E, ×10). Although thedefinitive definitive diagnosis of cystic histopathological Although the diagnosis of cystic lesionslesions requiresrequires histopathological analysis, analysis, clinical and radiological examinations are of paramount importance the in clinical and radiological examinations are of paramount importance in establishing establishing the differential diagnosis [8,9].theInpresumptive the case ofpreoperative DC, the presumptive differential diagnosis [8,9]. In the case of DC, diagnosis is preoperative is usually based on [1,9,10]. an analysis of OPG images signs [1,9,10]. usually baseddiagnosis on an analysis of OPG images Certain radiological are Certain specific, radiological signs are specific, while others are non-specific or variable. The radiological while others are non-specific or variable. The radiological peculiarity of DCs, which peculiarity of DCs, which facilitates theirthe recognition, the facttothat the lesions are facilitates their recognition, is the fact that lesions are is attached the cementoenamel attached to the cementoenamel junction and surround the tooth crown of an impacted junction and surround the tooth crown of an impacted tooth [8–10]. The center of the tooth [8,9,10]. The center cystthe may be located or below except cyst may be located aboveof orthe below crown, except above when the tooth isthe notcrown, in an upright when theor tooth is not anorients uprightlaterally positionduring or when cyst orients laterally during its position when the in cyst itsthe development. Other radiological development. Other signs, less specific to DC,generally, are the boundaries of the lesion: signs, less specific to radiological DC, are the boundaries of the lesion: well-defined, rounded, generally, well-defined, rounded, a thin sclerotic margin [4,8,11], and the radiolucent a thin sclerotic margin [4,8,11], and the radiolucent homogeneous, unilocular internal homogeneous, unilocular internal appearance of the On the other hand, appearance of the lesion [4–9]. On the other hand, the lesion effects[4,5,6,7,8,9]. on the surrounding anatomical the effects (adjacent on the surrounding anatomical (adjacent teeth, sinus bone cortex, IAC, structures teeth, bone cortex, IAC, structures nasal cavity, and maxillary floor) can be nasal cavity, and maxillary floor) can be variable and include discharge, variable and include discharge, sinus displacement, and expansion or resorption [8,9,12]. CBCT exam is very important in theordiagnosis of [8,9,12]. DC. Their appearance CBCT is similar to displacement, and expansion resorption CBCT exam is on very important in the panoramic of radiography, this exam provides more precise information on the size, diagnosis DC. Theirhowever, appearance on CBCT is similar to panoramic radiography, position, and relationship of the lesion to the surrounding structures. In classical helical computed tomography, the content of a DC typically appears as low density on CBCT Diagnostics 2022, 12, 2006 11 of 14 (liquid-like). The 3-dimensional analysis of the lesion enabled by CBCT provides precise and important information for clinicians developing a treatment strategy and surgical approach. A superior projection of the lesion on the nasal sinus cavities and displacement of the IAC can be accurately highlighted. Similarly, the expansion of the vestibular or lingual cortex is easily evaluated. Magnetic resonance imaging (MRI) has a very limited role in the diagnostics of this pathology, helping to distinguish these lesions from other cystic bone lesions only when the presentation is atypical. The contents of DC typically appear liquid-like on MRI (in hypointensity T1 and hyperintensity T2) and lack solids’ high-contrast partitions, except for occasional fine peripheral contrast enhancement when the cyst is infected. In the cases presented here, the presumptive radiological diagnosis of DC was confirmed by histopathological examination. However, in the OPG and CBCT images, the lesions varied in size, contour appearance, relationship, and effects on the surrounding anatomical structures. Differential radiological diagnoses differed from case to case and are summarized in Table 1. Table 1. Summary of the features of the presented cases. Case No Impacted Tooth DC Size Contour Relationship with Dental Anatomical Structures Adjacent teeth: 1 38, horizontal position with mesial orientation 27 × 22 mm (OPG and CBCT) Well defined, thin sclerotcs border of - Tooth 37, distal bone resorption No root resorption Discharge effect (distalized dental axis) Tooth vital Adjacent teeth: 2 48, inverted position with mesio-caudal orientation 13 × 15 mm (OPG) 13 × 17 × 15 mm (CBCT) Well defined, thin sclerotic border - - Severely resorbed apex of the distal root of tooth 47 Tooth vital Adjacent teeth: - 3 38, mesial 24 × 10 mm (OPT) 24 × 10 × 10 mm (CBCT) In places irregular, strongly sclerotic (sign of superinfection) - Suspicion of resorption of root apex 37 (OPT) Strongly resorbed root apex 37 (CBCT) Tooth 37 necrotic Relationship with Anatomical Bone Structures IAC: Signs of interference Strongly thinned wall Caudally displaced, no narrowing of the canal Cortex: Bubble-like vestibular and lingual cortex (infra-millimeter thinning) IAC: Signs of interference Caudally displaced Cranial cortex discontinuity Cortex: Bubble-like lingual cortex 4 mm alveolar crest dehiscence IAC: Apeces 38 interfering with IAC Internal canal deformation Cortex: 12-mm alveolar crest dehiscence lingually and 5-mm vestibulary Differential Diagnosis - Dentigerous cyst Keratocyst Unicystic ameloblastoma - Dentigerous cyst (root resorption means keratocyst was less likely) - Infected dentigerous cyst (root resorption means keratocyst was less likely) Diagnostics 2022, 12, 2006 12 of 14 Table 1. Cont. Case No 4 Impacted Tooth 38, distal DC Size 20 × 15 mm (OPG) 17 × 21 × 10 mm (CBCT) Contour Well defined, multilocular, thin septa, absence of periosteal reaction Relationship with Dental Anatomical Structures Relationship with Anatomical Bone Structures - IAC: Contact of superior edge (13 mm) IAC thinned wall No canal deformation Cortex: Bubble-like lingual and vestibular cortex Differential Diagnosis - Dentigerous cyst - Ameloblastoma Keratocyst Radiologically differential diagnosis of DC is mainly made with hyperplastic dental follicle, odontogenic keratocyst, and unicystic ameloblastoma. The following characteristics point toward a DC: neighboring tooth infiltration, bubble-like cortex, and the pericoronal space thicker than 5 mm [1,4,8,9,16]. An odontogenic keratocyst in pericoronal localization (about 21% of cases) can be considered in the differential diagnosis, especially in large lesions, but it causes bubble-like cortex and root resorption less frequently, has a slightly denser content in radiographic images [19–23], and never really attaches to the cementoenamel junction [8]. A unicystic ameloblastoma or an ameloblastic fibroma cannot be differentiated radiologically due to the absence of an internal structure [8,21]. A radicular cyst located at the apex of a deciduous tooth and surrounding the crown of the underlying permanent tooth can also resemble a cyst [8,24]. An odontogenic adenomatoid tumor or a calcified odontogenic cyst can also resemble a DC [8,24]. In this case series, the most likely differential diagnoses were keratocyst and unicystic ameloblastoma. The radiological findings that influenced the differential diagnosis were mainly the effects of the lesion on the adjacent anatomical structures (root resorption vs. infiltration) and the multilocular contour (case #4). On the other hand, although the 3D CBCT X-ray allowed us to appreciate the lesion volume and the relationship between the lesion and the surrounding structures, the differential diagnosis remained the same as the one deduced based on the OPT. For cases #2 and 3, the presumptive diagnosis of DC was quite high because of the classical appearance and the resorption of the adjacent roots made it possible to exclude keratocyst. This was in contrast to case #1, where the teeth/roots were displaced. Case #4, particularity, was the presence of a well-defined multilocular contour and the presence of septa, both of which, however, did not exclude the possibility of a keratocyst and ameloblastoma. When the DC is of large size, it can predispose the patient to pathological infections or fractures [8,9]. Rare cases of ameloblastic transformation in DC have been described in the literature [21]. The treatment of DC is represented by enucleation followed by curettage. It has been proposed that natural polymers may favorably help bone regeneration [25]. The use of local antibiotics after the enucleation of the cyst has been advocated [26], as well as the use of analgesics [27]. 4. Conclusions We have presented four examples of radiological presentation of DCs. Diagnosing DC lesions involved multiple aspects. Although it is most often based on OPT images where it appears as a radiolucent lesion surrounding an impacted tooth crown, other characteristics of the lesion should be taken into account since they may lead to a different differential diagnosis. Limitations of this study is the observational nature based on a small number of cases. Diagnostics 2022, 12, 2006 13 of 14 Author Contributions: Draft of the manuscript, preparation of images, patients treatment, A.P.; draft of the manuscript, radiological interpretation preparation of images, V.L.; conception, drafting and critical review of the manuscript, T.L. All authors have read and agreed to the published version of the manuscript. Funding: This research received no external funding. Institutional Review Board Statement: The presented study adhered to the Helsinki Declaration of ethical principles by the World Medical Association. The study did not require approval of Ethic Commission on Human Research of Geneva (CCER-Geneva), according to the Federal Human Research Act (Art.3al.a). Since the study involved less than five patients. Informed Consent Statement: Written informed consent has been obtained from the patients to publish this paper. Data Availability Statement: Not applicable. Conflicts of Interest: The authors declare no conflict of interest. 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