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Large calcifying odontogenic cyst in the posterior maxilla

RESUMEN

La aparición de un quiste odontogénico calcificante (QOC) en la región posterior de la maxila es infrecuente; hay pocos informes descritos en la literatura. Presentamos el caso de una paciente de 13 años que presentó una lesión extensa en la maxila izquierda (> 7,5 cm). La radiografía panorámica mostró una lesión radiolúcida unilocular bien delimitada, que se extendía desde el maxilar posterior izquierdo hasta el seno maxilar. La paciente fue sometida a descompresión, seguida de de la extirpación quirúrgica conservadora de la lesión. El análisis histológico de la pieza quirúrgica confirmó el diagnóstico de QOC. Después de un año, no se observaron recurrencias. La paciente permanece en seguimiento regular.

Palabras clave
quite odontogénico calcificante; descompresión; maxila; seno maxilar; tratamiento conservador

INTRODUCTION

The calcifying odontogenic cyst (COC) is an uncommon developmental cyst that accounts for less than 1% of all odontogenic cysts and tumors(11 Arruda JAA, Schuch LF, Abreu LG, Silva LVO, Monteiro JLG, Pinho RF. A multicentre study of 268 cases of calcifying odontogenic cysts and a literature review. Oral Dis. 2018; 24: 1282–93. PubMed PMID: 29856507.). The World Health Organization (WHO) defines COC as a cyst lined by ameloblastoma-like epithelium containing focal accumulations of ghost cells, dentinoid material and calcifications(22 El-Naggar AK, Chan JKC, Takata T, Grandis JR, Slootweg PJ. The fourth edition of the head and neck World Health Organization blue book: editors’ perspectives. Hum Pathol. 2017; 66: 10–12. PubMed PMID: 28583885.). In addition to COC, which is considered a non-neoplastic cystic condition, dentinogenic ghost cell tumor (a benign neoplasm) (DGCT) and ghost cell odontogenic carcinoma (a malignant neoplasm) (GCOC) complete the typical triad of ghost cell-containing odontogenic conditions(33 Soluk-Tekkeşin M, Wright JM. The World Health Organization classification of odontogenic lesions: a summary of the changes of the 2017 (4th) edition. Turk Patoloji Derg. 2018; 34(1): 1–18. PubMed PMID: 28984343.,44 Ledesma-Montes C, Gorlin RJ, Shear M, et al. International collaborative study on ghost cell odontogenic tumours: calcifying cystic odontogenic tumour, dentinogenic ghost cell tumour and ghost cell odontogenic carcinoma. J Oral Pathol Med. 2008; 37: 302–08. PubMed PMID: 18221328.). It is accepted that COC arises from remnants of the dental lamina(22 El-Naggar AK, Chan JKC, Takata T, Grandis JR, Slootweg PJ. The fourth edition of the head and neck World Health Organization blue book: editors’ perspectives. Hum Pathol. 2017; 66: 10–12. PubMed PMID: 28583885.) and several studies have studied the immunoexpression of cytokeratins and the presence of Wnt/β-catenin signaling pathway proteins in COC, suggesting their importance in the development and progression of these lesions(55 Fregnani ER, Pires FR, Quezada RD, Shih le M, Vargas PA, de Almeida OP. Calcifying odontogenic cyst: clinicopathological features and immunohistochemical profile of 10 cases. J Oral Pathol Med. 2003; 32: 163–70. PubMed PMID: 12581386.,66 Dutra SN, Pires FR, Armada L, Azevedo RS. Immunoexpression of Wnt/β-catenin signaling pathway proteins in ameloblastoma and calcifying cystic odontogenic tumor. J Clin Exp Dent. 2017; 9(1): e136–40. PubMed PMID: 28149478.).

COC may appear clinically as an intraosseous or an extraosseous/peripheral lesion(22 El-Naggar AK, Chan JKC, Takata T, Grandis JR, Slootweg PJ. The fourth edition of the head and neck World Health Organization blue book: editors’ perspectives. Hum Pathol. 2017; 66: 10–12. PubMed PMID: 28583885.). The most common presentation is a slow-growing swelling in the anterior region of the maxillary bones and jaw, affecting young adults in the third or fourth decades of life(22 El-Naggar AK, Chan JKC, Takata T, Grandis JR, Slootweg PJ. The fourth edition of the head and neck World Health Organization blue book: editors’ perspectives. Hum Pathol. 2017; 66: 10–12. PubMed PMID: 28583885.,44 Ledesma-Montes C, Gorlin RJ, Shear M, et al. International collaborative study on ghost cell odontogenic tumours: calcifying cystic odontogenic tumour, dentinogenic ghost cell tumour and ghost cell odontogenic carcinoma. J Oral Pathol Med. 2008; 37: 302–08. PubMed PMID: 18221328.). The COC presents as well-defined unilocular or multilocular radiolucencies associated with the variable presence of radiopaque foci(77 Yoshiura K, Tabata O, Miwa K, et al. Computed tomographic features of calcifying odontogenic cysts. Dentomaxillofac Radiol. 1998; 27: 12–16. PubMed PMID: 9482016.99 Sheikh J, Cohen MD, Ramer N, Payami A. Ghost cell tumors. J Oral Maxillofac Surg. 2017; 75(4): 750–58. PubMed PMID: 27865804.). They can be associated with unerupted teeth, mostly the upper canines, and can produce root resorption in the adjacent teeth(1010 Tanimoto K, Tomita S, Aoyama M, Furuki Y, Fujita M, Wada T. Radiographic characteristics of the calcifying odontogenic cyst. Int J Oral Maxillofac Surg. 1988; 17: 29–32. PubMed PMID: 3127486.,1111 Utumi ER, Pedron IG, da Silva LP, Machado GG, Rocha AC. Different manifestations of calcifying cystic odontogenic tumor. Einstein. 2012; 10(3): 366–70. PubMed PMID: 23386019.). Most COCs measure from 2 to 4 cm at the time of diagnosis, but some cases can reach larger proportions(1212 Buchner A. The central (intraosseous) calcifying odontogenic cyst: an analysis of 215 cases. J Oral Maxillofac Surg. 1991; 49(4): 330–9. PubMed PMID: 2005490.).

COC can be diagnosed in association with other odontogenic cysts and tumors, mostly odontomas(88 Zornosa X, Muller S. Calcifying cystic odontogenic tumour. Head Neck Pathol. 2010; 4(4): 292–94. PubMed PMID: 20658217.). Despite its growth potential, COC treatment is based on a conservative surgical approach, and marsupialization/decompression is sometimes indicated for extensive lesions(11 Arruda JAA, Schuch LF, Abreu LG, Silva LVO, Monteiro JLG, Pinho RF. A multicentre study of 268 cases of calcifying odontogenic cysts and a literature review. Oral Dis. 2018; 24: 1282–93. PubMed PMID: 29856507.). Recurrence after conservative management of COC is low(11 Arruda JAA, Schuch LF, Abreu LG, Silva LVO, Monteiro JLG, Pinho RF. A multicentre study of 268 cases of calcifying odontogenic cysts and a literature review. Oral Dis. 2018; 24: 1282–93. PubMed PMID: 29856507.). The aim of this paper is to report the case of a large maxillary COC with emphasis on its clinical, pathological and treatment features.

CASE REPORT

A 13-year-old girl was referred for evaluation of a swelling in the left maxilla associated with teeth mobility in the area lasting six months. An extraoral examination revealed a swelling in the infraorbital, paranasal, and left zygomatic regions. Intraoral examination revealed a swelling in the upper left vestibule extending from the first premolar to the third molar associated with mobility on teeth 25, 26 and 27. Medical history revealed no abnormalities.

Panoramic radiograph showed a well-defined unilocular radiolucent area in the left maxilla extending from the right central incisor to the left third molar (Figure 1A). Root resorption in the adjacent teeth was observed, as well as several radiopaque foci inside of the lesion. Computed tomography (CT) scans showed swelling and perforation of both buccal and palatal cortical bones (Figure 1B and C). The lesion occupied almost the entire left maxillary sinus and it was in close proximity to the orbit floor, measuring 7.5 cm in its largest diameter. Clinical diagnosis included ameloblastoma, odontogenic keratocyst, and COC. An incisional biopsy was performed. As the intraoperative features were compatible with a cystic lesion, a decompression with a tube was performed (Figure 2A). Histological analysis of the hematoxylin and eosin (HE)-stained slides revealed a cystic cavity lined by an epithelium composed of a basal layer of polarized columnar cells and a superficial area resembling the stellate reticulum. In addition, ghost cells and calcifications were present in the epithelium, rendering the diagnosis of COC.

FIGURE 1
A) panoramic radiograph showing an extensive radiolucency extending from the upper right central incisor to the upper left third molar. Note the presence of radiopaque foci and root resorption of the teeth closely associated with the lesion; B) axial and C) CBCT images showing the large dimensions of the lesion
FIGURE 2
A) initial surgical approach for cyst decompression. Note the vestibular expansion associated with the lesion; B) conservative surgical removal of the lesion showing buccal expansion; C) surgical specimen associated with the upper right central incisor and third mola

The patient underwent monthly routine clinical follow-up and was submitted to a conservative surgical removal of the lesion under general anesthesia after six months (Figure 2B and C). The procedure included a vertical para-papillary incision between teeth 11 and 22 and a sulcular incision of tooth 11 to 27 to access the lesion. After the excision was completed, curettage and peripheral osteotomy were performed in the entire bone cavity to remove any epithelial remnants and to reduce the risk of recurrence. The surgical specimen confirmed the presence of a cystic cavity and histological analysis confirmed the diagnosis of COC (Figure 3A and B). Panoramic view and CT scans revealed bone formation throughout the area (Figure 4A and B). The patient remains in clinical follow-up for one year with no signs of recurrence (Figure 4C).

FIGURE 3
A) detail of the surgical specimen showing the cyst cavity; B) HE stained histological section showing the cyst lining composed by basal cells, areas resembling stellate reticulum, ghost cells and calcifications (HE, 100× magnification)
FIGURE 4
A) panoramic view; B) axial CBCT images taken one year after surgery showing evidence of bone formation in the region (red arrows); C) intraoral appearance one year after surgery

DISCUSSION

COCs are uncommon, distinctive, and characterized as benign cystic odontogenic lesions with a predilection for the anterior region of the jaws. It may involve bone or extraosseous/peripheral tissues(22 El-Naggar AK, Chan JKC, Takata T, Grandis JR, Slootweg PJ. The fourth edition of the head and neck World Health Organization blue book: editors’ perspectives. Hum Pathol. 2017; 66: 10–12. PubMed PMID: 28583885.). COC was first described by Gorlin in 1962 as a cystic lesion, but it shares many clinical, radiological and histological characteristics with its solid counterpart, the DGCT(33 Soluk-Tekkeşin M, Wright JM. The World Health Organization classification of odontogenic lesions: a summary of the changes of the 2017 (4th) edition. Turk Patoloji Derg. 2018; 34(1): 1–18. PubMed PMID: 28984343.,1313 Gorlin RJ, Pindborg JJ, Clausen FP, Vickers RA. The calcifying odontogenic cyst--a possible analogue of the cutaneous calcifying epithelioma of Malherbe. An analysis of fifteen cases. Oral Surg Oral Med Oral Pathol. 1962; 15: 1235–43. PubMed PMID: 13949298.,1414 Irani S, Foroughi F. Histologic variants of calcifying odontogenic cyst: a study of 52 cases. J Contemp Dent Pract. 2017; 18(8): 688–94. PubMed PMID: 28816191.). Extensive maxillary COC (> 4 cm) in the posterior region are rare, with only a few cases reported in the literature (Table).

TABLE
Summary of extensive (larger than 4 cm) calcifying odontogenic cysts in the posterior maxillary region (premolar to molar) reported in the English language literature

In a study of 215 cases of COC by Buchner (1991)(1212 Buchner A. The central (intraosseous) calcifying odontogenic cyst: an analysis of 215 cases. J Oral Maxillofac Surg. 1991; 49(4): 330–9. PubMed PMID: 2005490.), the size of the lesion was known in 58 cases, ranging from 0.5 to 12 cm. Of these, almost 60% were sized between 2 and 3.9 cm, and the average recorded size was 3.3 cm. The average age at the time of presentation of extensive COC cases collected from the literature (Table), was 31 ± 17.2 years (ranging 13 to 62 years), without any gender predilection. The occurrence of these lesions in the posterior maxillary region is generally low, representing from 2% to 11.7% of all cases(1212 Buchner A. The central (intraosseous) calcifying odontogenic cyst: an analysis of 215 cases. J Oral Maxillofac Surg. 1991; 49(4): 330–9. PubMed PMID: 2005490.). Extensive COC can be associated with increased volume, malocclusion, painful sensation, aesthetic deformity, and risk of compromising adjacent anatomical structures(1515 Rushton VE, Horner K. Calcifying odontogenic cyst-a characteristic CT finding. Br J Oral Maxillofac Surg. 1997; 35: 196–98. PubMed PMID: 9212299.1717 Arboleda PA, Sánchez-Romero C, de Almeida OP, Flores Alvarado SA, Martínez Pedraza R. Calcifying odontogenic cyst associated with dentigerous cyst in a 15-year-old girl. Int J Surg Pathol. 2018; 26(8): 758–65. PubMed PMID: 24119871.). Likewise, in a multicenter study of 268 cases of COC, Arruda et al. (2018)(11 Arruda JAA, Schuch LF, Abreu LG, Silva LVO, Monteiro JLG, Pinho RF. A multicentre study of 268 cases of calcifying odontogenic cysts and a literature review. Oral Dis. 2018; 24: 1282–93. PubMed PMID: 29856507.) found that the size of the lesion was larger among symptomatic lesions. In these cases, the most common radiographic findings are bone expansion, that may or may not be accompanied by cortical erosion, tooth displacement, root resorption, and occasionally, the involvement of the maxillary sinus(77 Yoshiura K, Tabata O, Miwa K, et al. Computed tomographic features of calcifying odontogenic cysts. Dentomaxillofac Radiol. 1998; 27: 12–16. PubMed PMID: 9482016.,1010 Tanimoto K, Tomita S, Aoyama M, Furuki Y, Fujita M, Wada T. Radiographic characteristics of the calcifying odontogenic cyst. Int J Oral Maxillofac Surg. 1988; 17: 29–32. PubMed PMID: 3127486.,1717 Arboleda PA, Sánchez-Romero C, de Almeida OP, Flores Alvarado SA, Martínez Pedraza R. Calcifying odontogenic cyst associated with dentigerous cyst in a 15-year-old girl. Int J Surg Pathol. 2018; 26(8): 758–65. PubMed PMID: 24119871.,1818 Kim Y, Choi BE, Ko SO. Conservative approach to recurrent calcifying cystic odontogenic tumor occupying the maxillary sinus: a case report. J Korean Assoc Oral Maxillofac Surg. 2016; 42(5): 315–20. PubMed PMID: 27847742.). Similarly, the lesion described in our report extended throughout the maxillary sinus and occupied part of the floor of the left orbit, causing increased volume in the maxilla.

The distinctive histology of COC is characterized by an ameloblastoma-like epithelium lining a cystic cavity, associated with the presence of ghost cells and calcifications, and dentinoid formation(22 El-Naggar AK, Chan JKC, Takata T, Grandis JR, Slootweg PJ. The fourth edition of the head and neck World Health Organization blue book: editors’ perspectives. Hum Pathol. 2017; 66: 10–12. PubMed PMID: 28583885.,1414 Irani S, Foroughi F. Histologic variants of calcifying odontogenic cyst: a study of 52 cases. J Contemp Dent Pract. 2017; 18(8): 688–94. PubMed PMID: 28816191.). COC has been previously classified into different histological variants (simple cyst, proliferative cyst, ameloblastomatous type, and associated with odontoma or other benign odontogenic tumors other than odontoma) but this classification does not seem to have clinical and behavioral significance. Therefore it has not been adopted by the WHO classification(22 El-Naggar AK, Chan JKC, Takata T, Grandis JR, Slootweg PJ. The fourth edition of the head and neck World Health Organization blue book: editors’ perspectives. Hum Pathol. 2017; 66: 10–12. PubMed PMID: 28583885.,1414 Irani S, Foroughi F. Histologic variants of calcifying odontogenic cyst: a study of 52 cases. J Contemp Dent Pract. 2017; 18(8): 688–94. PubMed PMID: 28816191.,1717 Arboleda PA, Sánchez-Romero C, de Almeida OP, Flores Alvarado SA, Martínez Pedraza R. Calcifying odontogenic cyst associated with dentigerous cyst in a 15-year-old girl. Int J Surg Pathol. 2018; 26(8): 758–65. PubMed PMID: 24119871.). When evaluating the histological variant of 52 cases of COC, Irani et al. (2017)(1414 Irani S, Foroughi F. Histologic variants of calcifying odontogenic cyst: a study of 52 cases. J Contemp Dent Pract. 2017; 18(8): 688–94. PubMed PMID: 28816191.) observed that the simple cystic and odontoma-associated COC rate was 30.8% for both subtypes, being the most commonly found histological types. As described in Table, odontoma is the most common COC-associated odontogenic tumor in larger lesions.

Enucleation is the treatment of choice for intraosseous COC and recurrences are observed in less than 5% of the cases(11 Arruda JAA, Schuch LF, Abreu LG, Silva LVO, Monteiro JLG, Pinho RF. A multicentre study of 268 cases of calcifying odontogenic cysts and a literature review. Oral Dis. 2018; 24: 1282–93. PubMed PMID: 29856507.,1212 Buchner A. The central (intraosseous) calcifying odontogenic cyst: an analysis of 215 cases. J Oral Maxillofac Surg. 1991; 49(4): 330–9. PubMed PMID: 2005490.). This therapeutic modality is seen as an effective technique even for larger lesions, as it avoids unnecessary mutilation and tooth loss(1616 Emam HA, Smith J, Briody A, Jatana CA. Tube decompression for staged treatment of a calcifying odontogenic cyst – a case report. J Oral Maxillofac Surg. 2017; 75(9): 1915–20. PubMed PMID: 28390759.,1919 Sakai VT, Couto Filho CEG, Moretti ABS, Pereira AAC, Hanemann JAC, Duque JA. Conservative surgical treatment of an aggressive calcifying cystic odontogenic maxillary tumor in the young permanent dentition. Pediatr Dent. 2011; 33(3): 261–5. PubMed PMID: 21703081.). As seen in Table, enucleation was performed in 87.5% (7/8) of the extensive COC included in our review. Arruda et al. (2018)(11 Arruda JAA, Schuch LF, Abreu LG, Silva LVO, Monteiro JLG, Pinho RF. A multicentre study of 268 cases of calcifying odontogenic cysts and a literature review. Oral Dis. 2018; 24: 1282–93. PubMed PMID: 29856507.) found that only 4% of COC reported in the literature were managed through a two-step approach, including decompression or marsupialization followed by enucleation. Particularly, we have shown a conservative two-step approach to COC with good clinical results in the present report. Apart from that, COC rarely undergoes malignant transformation(2020 Tarakji B, Ashok N, Alzoghaibi I, et al. Malignant transformation of calcifying cystic odontogenic tumour – a review of literature. Contemp Oncol. 2015; 19(3): 184–86. PubMed PMID: 26557757.), reinforcing the utility of this conservative surgical approach even for large posterior maxillary COC.

In summary, we report a case of an extensive posterior maxillary COC treated conservatively with the improvement of the patient’s overall condition. The present case reinforces that decompression should be considered as an option in large lesions in young patients, reducing the morbidity and thus helping the preservation of important anatomical structures.

REFERENCES

  • 1
    Arruda JAA, Schuch LF, Abreu LG, Silva LVO, Monteiro JLG, Pinho RF. A multicentre study of 268 cases of calcifying odontogenic cysts and a literature review. Oral Dis. 2018; 24: 1282–93. PubMed PMID: 29856507.
  • 2
    El-Naggar AK, Chan JKC, Takata T, Grandis JR, Slootweg PJ. The fourth edition of the head and neck World Health Organization blue book: editors’ perspectives. Hum Pathol. 2017; 66: 10–12. PubMed PMID: 28583885.
  • 3
    Soluk-Tekkeşin M, Wright JM. The World Health Organization classification of odontogenic lesions: a summary of the changes of the 2017 (4th) edition. Turk Patoloji Derg. 2018; 34(1): 1–18. PubMed PMID: 28984343.
  • 4
    Ledesma-Montes C, Gorlin RJ, Shear M, et al. International collaborative study on ghost cell odontogenic tumours: calcifying cystic odontogenic tumour, dentinogenic ghost cell tumour and ghost cell odontogenic carcinoma. J Oral Pathol Med. 2008; 37: 302–08. PubMed PMID: 18221328.
  • 5
    Fregnani ER, Pires FR, Quezada RD, Shih le M, Vargas PA, de Almeida OP. Calcifying odontogenic cyst: clinicopathological features and immunohistochemical profile of 10 cases. J Oral Pathol Med. 2003; 32: 163–70. PubMed PMID: 12581386.
  • 6
    Dutra SN, Pires FR, Armada L, Azevedo RS. Immunoexpression of Wnt/β-catenin signaling pathway proteins in ameloblastoma and calcifying cystic odontogenic tumor. J Clin Exp Dent. 2017; 9(1): e136–40. PubMed PMID: 28149478.
  • 7
    Yoshiura K, Tabata O, Miwa K, et al. Computed tomographic features of calcifying odontogenic cysts. Dentomaxillofac Radiol. 1998; 27: 12–16. PubMed PMID: 9482016.
  • 8
    Zornosa X, Muller S. Calcifying cystic odontogenic tumour. Head Neck Pathol. 2010; 4(4): 292–94. PubMed PMID: 20658217.
  • 9
    Sheikh J, Cohen MD, Ramer N, Payami A. Ghost cell tumors. J Oral Maxillofac Surg. 2017; 75(4): 750–58. PubMed PMID: 27865804.
  • 10
    Tanimoto K, Tomita S, Aoyama M, Furuki Y, Fujita M, Wada T. Radiographic characteristics of the calcifying odontogenic cyst. Int J Oral Maxillofac Surg. 1988; 17: 29–32. PubMed PMID: 3127486.
  • 11
    Utumi ER, Pedron IG, da Silva LP, Machado GG, Rocha AC. Different manifestations of calcifying cystic odontogenic tumor. Einstein. 2012; 10(3): 366–70. PubMed PMID: 23386019.
  • 12
    Buchner A. The central (intraosseous) calcifying odontogenic cyst: an analysis of 215 cases. J Oral Maxillofac Surg. 1991; 49(4): 330–9. PubMed PMID: 2005490.
  • 13
    Gorlin RJ, Pindborg JJ, Clausen FP, Vickers RA. The calcifying odontogenic cyst--a possible analogue of the cutaneous calcifying epithelioma of Malherbe. An analysis of fifteen cases. Oral Surg Oral Med Oral Pathol. 1962; 15: 1235–43. PubMed PMID: 13949298.
  • 14
    Irani S, Foroughi F. Histologic variants of calcifying odontogenic cyst: a study of 52 cases. J Contemp Dent Pract. 2017; 18(8): 688–94. PubMed PMID: 28816191.
  • 15
    Rushton VE, Horner K. Calcifying odontogenic cyst-a characteristic CT finding. Br J Oral Maxillofac Surg. 1997; 35: 196–98. PubMed PMID: 9212299.
  • 16
    Emam HA, Smith J, Briody A, Jatana CA. Tube decompression for staged treatment of a calcifying odontogenic cyst – a case report. J Oral Maxillofac Surg. 2017; 75(9): 1915–20. PubMed PMID: 28390759.
  • 17
    Arboleda PA, Sánchez-Romero C, de Almeida OP, Flores Alvarado SA, Martínez Pedraza R. Calcifying odontogenic cyst associated with dentigerous cyst in a 15-year-old girl. Int J Surg Pathol. 2018; 26(8): 758–65. PubMed PMID: 24119871.
  • 18
    Kim Y, Choi BE, Ko SO. Conservative approach to recurrent calcifying cystic odontogenic tumor occupying the maxillary sinus: a case report. J Korean Assoc Oral Maxillofac Surg. 2016; 42(5): 315–20. PubMed PMID: 27847742.
  • 19
    Sakai VT, Couto Filho CEG, Moretti ABS, Pereira AAC, Hanemann JAC, Duque JA. Conservative surgical treatment of an aggressive calcifying cystic odontogenic maxillary tumor in the young permanent dentition. Pediatr Dent. 2011; 33(3): 261–5. PubMed PMID: 21703081.
  • 20
    Tarakji B, Ashok N, Alzoghaibi I, et al. Malignant transformation of calcifying cystic odontogenic tumour – a review of literature. Contemp Oncol. 2015; 19(3): 184–86. PubMed PMID: 26557757.

Publication Dates

  • Publication in this collection
    29 Nov 2021
  • Date of issue
    2021

History

  • Received
    05 Apr 2020
  • Reviewed
    05 Apr 2020
  • Accepted
    05 Apr 2020
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