
==== Front
Int J Surg Case Rep
Int J Surg Case Rep
International Journal of Surgery Case Reports
2210-2612
Elsevier

S2210-2612(24)00937-4
10.1016/j.ijscr.2024.110156
110156
Case Report
A case report of a huge unicystic ameloblastoma in the mandible with significant reduction through marsupialization
Harazono Yosuke yharmfs@tmd.ac.jp
a⁎
Thai Huy Thanh ab
Vu Duc Viet a
Takahara Namiaki a
Yoda Tetsuya a
a Department of Maxillofacial Surgery, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8549, Japan
b Department of Oral and Maxillofacial Surgery, Faculty of Dentistry, Nguyen Tat Thanh University, Ho Chi Minh City 700000, Viet Nam
⁎ Corresponding author. yharmfs@tmd.ac.jp
16 8 2024
10 2024
16 8 2024
123 11015612 7 2024
8 8 2024
10 8 2024
© 2024 The Authors
2024
https://creativecommons.org/licenses/by-nc-nd/4.0/ This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
Introduction

Marsupialization is a dependable choice for mandibular unicystic ameloblastoma (UA) management. However, investigations regarding its speed of shrinkage (SS) and reduction rate (RR) are lacking. This case report highlights the treatment of a huge mandibular UA with high SS and RR using marsupialization before secondary surgery.

Presentation of case

A 45-year-old male patient presented with severe swelling of the right side of the mandible, resulting in prominent facial asymmetry. Panoramic radiograph revealed a unilocular, radiolucent lesion extending from the mandibular midline to the right ramus. Computed tomography (CT) revealed a large radiolucent lesion that expanded in the buccolingual direction. Incisional biopsy showed that the lesion was UA. After 1.5 years of marsupialization, an SS of 0.183 % per day was reached, leading to an impressive RR of 98.7 %. Treatment was followed by enucleation and peripheral osteotomy. No recurrence was observed at 1 year post-surgery.

Discussion

The treatment of mandibular UA remains controversial, ranging from conservative approaches to aggressive interventions. In the current case, marsupialization was highly effective in reducing the volume of the lesion, thereby facilitating a minimally invasive secondary surgery to preserve function. The intact periosteum, which has the potential to differentiate into various cell types, may be associated with the regeneration of new bone after marsupialization.

Conclusion

Marsupialization remains a successful strategy for managing mandibular UA. Even the huge lesions causing facial deformity can be treated with marsupialization combined with secondary surgery, avoiding the aesthetic and functional disruptions associated with radical treatment.

Highlights

• Marsupialization aids in managing mandibular unicystic ameloblastoma (UA).

• A 45-year-old man presented with right mandibular swelling, causing facial asymmetry.

• Marsupialization achieved no recurrence post-enucleation and peripheral osteotomy.

• Marsupialization is a successful strategy for mandibular UA.

Keywords

Case report
Unicystic ameloblastoma
Speed of shrinkage
Reduction rate
Marsupialization
Mandible
==== Body
pmc1 Introduction

Approximately 80 % of ameloblastomas develop in the mandible, mostly in proximity to the molar and ramus region [[1], [2], [3]]. The World Health Organization classifies ameloblastomas into four categories: conventional, unicystic, extraosseous/peripheral, and metastasizing [4]. Among these types, unicystic ameloblastoma (UA) accounts for 5 %–15 % of all ameloblastomas [5]. Controversial discussions have emerged surrounding the treatment approaches for mandibular UA, with a general classification into three categories: enucleation, marsupialization or decompression, and radical resection [6]. For relatively huge cystic lesions, radical treatment has disadvantages owing to many associated complications. Therefore, with the aim of reducing complications, marsupialization or decompression may be the primary therapeutic approach, with or without subsequent enucleation or curettage [[7], [8], [9], [10]].

The marsupialization involves creating an incision directly through the lesion, with or without suturing the fibrous wall of the cyst to the adjacent oral mucosa. This establishes a direct connection between the cystic lumen and oral mucosa, facilitating the release of intraluminal pressure and promoting the gradual formation of new bone [7,8]. Few studies have addressed the efficacy of marsupialization in the treatment of mandibular UA using a speed of shrinkage (SS) and reduction rate (RR). Earlier investigations documented RR ranging from 7.5 % to 96 % following marsupialization [[7], [8], [9], [10], [11]]. This case report aims to present the effective treatment of a huge mandibular UA by marsupialization before secondary surgery. It is noteworthy that the RR in this case was 98.7 %, exceeding all previous reports. This work has been reported in line with the SCARE criteria [12].

2 Presentation of case

A 45-year-old male patient presented to our hospital with a primary concern of severe swelling on the right side of his face. Four years ago, the swelling developed at this location and progressively increased in size. Medical history indicated that the patient had undergone extraction of the third molar and enucleation of a cyst in the right mandible 20 years prior. The patient had no other systemic diseases and reported smoking 10 cigarettes per day over the past 10 years. Upon extraoral examination, a firm, well-defined swelling, approximately 15 cm in diameter, was observed in the right cheek, resulting in noticeable facial asymmetry (Fig. 1A). Intraoral examination confirmed a palpable hard lesion with a characteristic “Ping-Pong ball” sign in this area. Except for the aesthetic issue due to facial asymmetry, the patient did not experience pain, paraesthesia, or functional disturbances. Panoramic radiograph revealed a clearly defined, unilocular, radiolucent lesion extending from the right mandibular lateral incisor to the right mandibular ramus. Substantial bone resorption was evident with only a thin radiopaque layer visible at the outer margin. Root resorption was observed in the right mandibular canine, the first and second premolars (Fig. 1B). Computed tomography (CT) revealed a large radiolucent lesion expanding in the buccolingual direction, causing resorption of most of the cortical bone (Fig. 1C).Fig. 1 (A) A severe swelling on the right cheek led to facial asymmetry. (B and C) Images of panoramic radiograph and computed tomography revealed a large radiolucent area.

Fig. 1

At the time of biopsy, a definitive diagnosis of UA was made. The management involved conservative surgery, including marsupialization and extraction of the first and second premolars, performed by a skilled surgeon. Antibiotic gauze was applied immediately after marsupialization to prevent the collapse of the periosteum scaffold. The gauze was removed, and the wound was covered with an obturator. Hematoxylin and eosin-stained histological sections revealed ameloblastic epithelium with loose adhesions and a surrounding dense fibrous wall. Irregular extensions of the epithelial legs into the lumen were evident with no observed keratinization or cellular variants, suggesting an intraluminal UA subtype (Fig. 2A and B). The patient underwent strict and regular check-ups to monitor changes in the radiolucent area. Remarkably, with an SS of 0.183 % per day, the volume decreased by 98.7 % 1.5 years after marsupialization (Fig. 3). Subsequently, enucleation combined with peripheral osteotomy was performed to eliminate the remaining tissue. One-year postoperative follow-up revealed excellent healing with favorable functional and aesthetic outcomes (Fig. 4A and B). In the future, the patient will continue to be monitored for potential recurrence.Fig. 2 (A and B) The histological examination showed ameloblastic epithelium with projections (yellow arrows) into the lumen. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)

Fig. 2

Fig. 3 Volumetric change of the lesion after marsupialization.

Fig. 3

Fig. 4 1 year after enucleation combined with peripheral osteotomy. (A) Facial asymmetry is significantly improved. (B) Panoramic radiograph revealed clear bone growth with no evidence of recurrence.

Fig. 4

3 Discussion

UAs appear as a unique singular cavity and are categorized into luminal, intraluminal, and mural subtypes according to their histopathological features [6,11]. In the luminal type, the ameloblastic epithelium is limited to the luminal surface, whereas in the intraluminal type, it protrudes into the lumen, and in the mural type, it infiltrates the connective tissue wall [6]. Treatment options for UA vary from conservative approaches (marsupialization or decompression, enucleation, and curettage with or without cryotherapy, chemical and electrocautery, and radiation therapy) to more aggressive approaches (marginal or segmental resection) or a combination of surgery and radiation [6,11]. The recurrence rate of conservative treatment was found to be higher than that of radical treatment [1,6,10], with resection having a recurrence rate of 3.6 %, enucleation alone at 30.5 %, enucleation with Carnoy's solution at 16 %, and marsupialization at 18% [6]. The management of UA lacks a standardized protocol and remains controversial. Factors that influence the selection of treatment approaches include the characteristics of the lesion (size, location, and histology), patient age and cooperation, and surgeon expertise.

Nakamura et al. initially proposed a method to assess the impact of marsupialization on odontogenic keratocysts using panoramic radiographs, focusing on RR [13]. This rate was determined by comparing the pixel counts of the cysts through radiographs before and after marsupialization. Marsupialization efficacy was further categorized into three groups: extremely effective (RR > 80 %), moderately effective (50 % < RR < 80 %), and poorly effective (RR < 50 %). For UA, limited research has evaluated the efficacy of marsupialization using SS and RR. These studies can be divided into two groups: those utilizing panoramic evaluation, and those utilizing CT evaluation (Table 1) [[7], [8], [9], [10], [11]]. Although panoramic radiographs demonstrate a linear correlation between the volume of cystic cavities and radiolucent areas, their lack of three-dimensional representation can lead to inaccuracies. Recently, CT has been used to examine morphological changes. In the present case, we utilized the image analysis software (3D Slicer, http://www.slicer.org) for 3D imaging and measured the volume of the lesion [14]. We found that the lesion size decreased significantly, with an RR of 98.7 % after marsupialization, which is much higher than that reported in previous studies. The result was classified as extremely effective according to Nakamura's efficacy categories. Peak RR was attained within the initial 3 months, which is consistent with the findings of Tomomatsu et al. [8]. The authors suggested waiting 3–6 months post-marsupialization to ensure sufficient bone formation before enucleation. Maximum reduction typically occurs approximately 4.5 months after marsupialization [8]. Determining the exact timing for initiating the secondary treatment is challenging because it varies according to patients. In the present case, marsupialization lasted for approximately 1.5 years because of the considerable size of the lesion, necessitating time to reduce it to a sufficiently small size before safe removal could be administered. Therefore, the SS in this case was 0.183 % per day, which is approximately equal to that in Mohamed's study but lower than that in other studies with a follow-up duration of 5–6 months before the secondary surgery [[7], [8], [9]].Table 1 Articles about marsupialization of unicystic ameloblastoma that include reduction rate and/or speed of shrinkage.

Table 1Type of evaluation	Authors	Number of patients	Age (years)	Techniques	Extremely effective proportion (%)	Speed of shrinkage (% per day)	Reduction rate (%)	Follow-up duration (before secondary surgery)	
Panoramic radiograph	Yang et al. (2018) [10]	46	ND	Marsupialization
Curettage/Dredging	ND	0.206	ND	ND	
Zheng et al. (2019) [11]	116	22.32 ± 9.46a	Marsupialization
Enucleation	ND	ND	7.5-96	7–25 months	
Computed tomography	Matsuda et al. (2019) [9]	4	29 ± 21.65	Marsupialization
Enucleation	0	0.327 ± 0.044a	56.42 ± 7.6	5.75 ± 1.71 months	
Tomomatsu et al. (2021) [8]	12	ND	Marsupialization
Enucleation	68	0.343 ± 0.187a	49.7 ± 18.3	3–12 months	
Mohamed et al. (2022) [7]	31	24 ± 9	Marsupialization
Curettage/Dredging	ND	0.189 ± 0.096	63.3 ± 20.1	440 ± 349 days	
Present case	1	45	Marsupialization
Enucleation+Peripheral osteotomy	100	0.183	98.7	18 months	
ND: Not described.

a The overall mean and standard deviation were calculated based on the data provided in the article.

The role of the periosteum must be considered in the significant reduction of lesion volume. Cells within the periosteum have the potential to differentiate into various cell types, including chondrocytes and osteoblasts [15]. The integrity of the periosteum, along with its continuous connection to surrounding living tissues, not only makes it a space maintainer but also serves as a biological membrane for bone regeneration [16]. In the present case, extensive bone resorption posed a significant challenge to the healing process. Fortunately, the periosteum remained intact, allowing the initial layers of bone to be deposited on the periosteal scaffold. Muhammad described a case of a huge solitary bone cyst with an inner lining resembling the periosteum [17]. Preservation of the periosteum resulted in excellent bone regeneration on all sides of the cyst cavity after marsupialization [17]. Tomomatsu et al. found that initiating marsupialization before enucleation was highly effective for large cystic lesions, particularly when the cortical bone of the mandible was extensively absorbed. This approach promoted new bone formation and facilitated lesion removal [8]. Intracystic pressure reduction after marsupialization also enhances the osteogenesis of bone marrow stromal cells around cystic lesions by increasing their differentiation capacity [18]. This process also decreases the expression of IL-1α and PGE-2 (inflammatory mediators that inhibit osteoclastogenesis), thereby promoting effective bone healing [19].

Thus, the advantage of this approach is that if the periosteum is intact, the lesion, regardless of its size, can be expected to shrink with bone formation. On the other hand, its drawback is that it requires at least a couple of months to see results after marsupialization.

4 Conclusion

The present case report highlights the effective treatment of a huge mandibular UA with marsupialization before secondary surgery with a high RR. Although various factors contribute to the choice of treatment, marsupialization remains an effective approach for mandibular UA, with positive outcomes in terms of patient aesthetics and function.

Patient perspective

The patient expressed satisfaction with the treatment received.

Consent of patient

Written informed consent was obtained from the patient for publication of this case report and accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal on request.

Ethical approval

The study is exempt from ethical approval in our institution.

Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Author contribution

Yosuke Harazono: concept, design, data collection, data analysis, interpretation, writing the paper and patient treatment.

Huy Thanh Thai: data collection, data analysis, interpretation, writing the paper.

Duc Viet Vu: data collection, data analysis.

Namiaki Takahara: writing the paper, patient treatment.

Tetsuya Yoda: concept, writing the paper.

Guarantor

Yosuke Harazono.

Research registration number

1. Name of the registry: N/A.

2. Unique identifying number or registration ID: N/A.

3. Hyperlink to your specific registration (must be publicly accessible and will be checked): N/A.

Conflict of interest statement

None.

Acknowledgement

None.
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