Odontogenic myxoma involving the right nasal cavity, orbital floor, and skull base in a 20-year-old woman: Removal and review of the literature

Abstract Odontogenic myxoma (OM) is a rare benign tumor in the jaws. It is considered locally aggressive but non-metastatic. Here, we report a case of Odontogenic myxoma observed at a relatively rare site, which occurs in the maxillary posterior interdental region and maxillary sinus, as well as involves the right nasal cavity, orbital floor, and skull base. A 20-year-old young female patient was referred to institution for right-sided nasal congestion and facial swelling. The right inferior nasal tract and common nasal tract of the patient were blocked with a reddish neoplasm. The clinical history and preoperative examination and iconography findings were indicative of an odontogenic cyst. The patient received Right-sided nasal sinus tumor resection via end nasal endoscopic anterior lacrimal saphenous fossa combined with Kollu’s approach. The postoperative pathological findings were suggestive of an Odontogenic myxoma. Conservative surgical treatment is less surgically invasive, more acceptable to patients, and results in a better quality of survival.


Introduction
Odontogenic myxoma (OM) was firstly described by Thoma and Goldman in 1947, and they attributed it to mesenchymal and/or odontogenic ectodermal mesenchyme [1,2].OM is a rare benign tumor in the jaws and is mainly seen in the tooth-bearing zone [3].It is considered locally aggressive but non-metastatic.The maxilla OM was more aggressive than the mandible OM.Maxillary Odontogenic myxomafrequently affects the paranasal sinus [4,5].The dispersed stellate and spindle-shaped cells in an abundant mucus-like extracellular matrix is one of the outstanding characteristics of OM, which may contain odontogenic epithelial cells [3].The overall incidence of OM is reported to be between 0.2% and 17.7% in all odontogenic tumors.The age at OM diagnosis is usually between 20 to 39 years, especially in females.
According to previous studies, the overall incidence of OM was an ethnic disparity.The West China College of Stomatology at Sichuan University conducted a retrospective analysis of 1642 cases of odontogenic tumors between 1952 and 2004 and discovered that only 4.6 per cent of odontogenic tumors in the Chinese population were caused by OM [6].Argentinean teenagers and Egyptian daiquiri had a higher incidence of OM, making up 8.5% of individuals with odontogenic tumors [7,8] and in a California survey of the United States performed that accounted for 2.2% [9].In this study, we reported a 20 years old female with OM, which occurs in the maxillary posterior interdental region and maxillary sinus, as well as involves the right nasal cavity, orbital floor, and skull base.

Case report
The patient, a 20-year-old female, was presented to the hospital with the primary complaint of 'right-sided nasal congestion for 2 years, exacerbated by facial swelling for 6 months.'The patient developed right-sided nasal congestion 2 years ago for no apparent reason, and it steadily intensified, accompanied by a runny nose, no headache, exophthalmos, and facial swelling.The patient had been visited at numerous other hospitals and was discovered to have a right paranasal sinus mass by nasal endoscopy and CT evaluation of the paranasal sinuses, and surgery was indicated.The aforementioned symptoms have been worse over the last six months and are now accompanied by facial swelling, protrusion of ophthalmoparesis, soreness when pressing on the face and eye, self-conscious slightly decreased right visual acuity, occasionally blurred vision, no movement restriction or diplopia, no loss of smell, etc. Examination: The right nasal inferior and common nasal tracts are filled with a light red tumor; the tumor has compressed and flattened the inferior turbinate medially and superiorly; the mass's surface is smooth, and its root cannot be seen.CT and MRI of the paranasal sinuses were done in order to determine the size, origin, and kind of tumor.The right maxilla had a large cystic low-density lesion that was significantly distended, unevenly enlarged, convened upward into the maxillary sinus significantly thinned adjacent sinus wall bone structure, obstructed the right nasal cavity inward, and had a tooth visible at the top.The cyst's CT value was about 26 HU, and its density was more uniform, with intact sinus wall bone (Figure 1) A MRI of the sinuses revealed a soft tissue mass with a low signal in T1WI and a high signal in T2W that was about 5.2 cm by 4.7 cm and was located in the right maxillary sinus, sieve sinus, and middle and lower nasal passages.The surrounding bone was destroyed, and the mass was enlarged adjacent to the ostium of the maxillary sinus.The lesion affected the maxilla, and protruded medially into the nasal cavity, absorbing the middle and inferior turbinate.Enhanced scan: The mass showed markedly heterogeneous 'gyruslike' enhancement (Figure 2).For diagnostic and therapeutic purposes, we surgically resected the lesion by performing a transnasal endoscopic anterior lacrimal fossa combined with Collis's approach to the right nasal sinus tumor (Figure 3), and a histological examination of the resected tissue was conducted.Macroscopically, the specimen was off-white in color and consisted of soft and hard tissues.Microscopic examination showed a polyp-like mass with scattered epithelial strips of odontogenic origin visible in the mucus-like interstitium, with no obvious heterogeneity, and the lesion was considered to be an Odontogenic myxoma tumor (Figure 4).Due to the excessive enormous lacuna, we employed Vaseline gauze and an expansion sponge to fill the nasal cavity and systemic intravenous antibiotic infusion to reduce the dead space and avoid postoperative infection.

Discussion
OM is commonly observed in the area of the mouth where teeth are present.The maxilla OM was more aggressive than the mandible OM and more likely to progress into the sinuses.For CT and MRI could not provide microcosmic details, the diagnosis of OM is often dependent on pathology.
In this case, CT exhibited a large cystic hypodense lesion in the right maxilla, with an intracapsular CT value of about 26 HU.Because of the lesion, the right maxilla was clearly distended and unevenly enlarged, convexed upward and occupied the maxillary sinus.The bone structure of the adjacent sinus wall was significantly thinned and obstructed the right nasal cavity inward as a result of the lesion.
According to the previous study, OM is a rare benign tumor and had overlapped clinical features with other diseases, which leads to being easily confused with other jaw tumors.However, the lesion causes the CT to show a cystic component with low signal separation in the focal area, which suggests a high possibility of OM [10].The preoperative clinical data could not provide efficient evidence to identify the patient as an Odontogenic myxoma tumor.Besides, this cystic hypodense lesion was more likely to be diagnosed as an odontogenic cyst according to its features in preoperative CT.To exclude intraosseous cystic lesions, central giant cell lesions, ameloblastomas, odontogenic keratotic cysts, or other osteolytic lesions, the preoperative diagnosis should be validated by pathologic biopsy.
Because the mucinous tumor in this patient had occupied the entire maxillary sinus cavity and was bulging toward the nasal septal surface, a trans maxillary sinus conventional opening approach was unable to expose the mass.In combination with CT and MRI, the right Odontogenic myxoma tumor occupied the entire maxillary sinus cavity; in order to better expose the mass and gain room for manipulation, we performed the procedure using a transnasal endoscopic anterior lacrimal fossa approach.A greyish-white mass that could not be reached by instruments was still present after using the 70-degree nasal endoscope to explore the anterior medial aspect of the maxillary sinus and the floor wall.so the mass was completely removed endoscopically in combination with the lacrimal gingival sulcus approach.The postoperative pathology was reported as an Odontogenic myxoma tumor.
Mucinous tumors are often removed surgically.The tumor has no envelope and is locally infiltrative, so if the procedure is not removed entirely, it may come back.When the tumor is big, a partial mandible or maxilla excision is the best surgical option to minimize recurrence.There are no clear guidelines for the surgical treatment of Odontogenic myxoma tumors.Saalim et al. [11] performed a statistical analysis of papers related to the treatment of 39 patients with Odontogenic myxoma tumors, Treatments were classified as conservative (curettage, enucleation with curettage, excision curettage, and excision) and resection.They classified curettage, enucleation with curettage, excision curettage, and excision as 'conservative treatment'.During a mean follow-up period of 10 years, the overall recurrence rate was 5 out of 39 patients (13%), the difference in the recurrence rate of Odontogenic myxoma tumors by conservative resection or radical surgery was not statistically significant (p ¼ 0.51), and maxillary lesions were more likely to recur than mandibular lesions.Zanetti et al. [12] strongly recommended conservative treatment with an extensive scraping of normal tissue or extensive apparently uninvolved surrounding tissue, or even peripheral osteotomy, with no way to preserve vital structures and maintain oral function.Boffano et al. [13] suggested conservative treatment when Odontogenic myxoma tumors are less than 3 cm in diameter, while segmental resection and immediate reconstruction are preferred Figure 3. (A) Transnasal endoscopic right anterior lacrimal saphenous approach.A1: The white dashed line shows the curved incision at the anterior edge of the inferior turbinate head by the anterior lacrimal saphenous approach.A2: grinding drill to grind away the bone of the inner wall of the maxillary sinus from anterior to posterior.A3: Greyish-white papillary neoplasm in the maxillary sinus.(B) Excision of maxillary sinus mass þ opening of the right inferior nasal tract.B1: a molar located in the posterosuperior wall of the maxillary sinus and encased in a greyish-white neoplasm.B2: After exfoliation of the swelling, the bone of the orbital floor wall was seen to be significantly thinned, and the blue-purple orbital tissue could have peered through the bone wall with the perichondrium intact and bluish.B3: a few bony defects in the posterior external wall of the maxillary sinus, with the dura mater of the inferior temporal fossa visible.(C) Endoscopic transtibial gingival sulcus section Lu's approach.C1: an approximately 3-cm-long incision in the right labiogingival sulcus.C2: Biting forceps to remove part of the bone of the anterior maxillary sinus wall until the floor wall of the maxillary sinus and the mass are completely exposed.C3: closure of the anterior aspect of the inferior turbinate and the lateral wall of the nasal cavity with 6-0 sutures.IT: inferior turbinate; SP: nasal septum; MS: maxillary sinus; LG: labiogingival groove; OF: orbital floor.
for larger patients.However, Yoko Kawase-Koga et al. [14] performed the removal and extensive scraping of the surrounding normal tissue in a patient with an Odontogenic myxoma tumor larger than 3 cm in diameter without recurrence at 10 years of follow-up.Conservative treatments are much less invasive, so we can use surgical approaches that preserve normal physiology and aesthetics as much as possible while minimizing the risk of recurrence.However, radical surgery is still required after conservatively treating OM recurrence [15,16].
We surgically resected the lesion by performing a transnasal endoscopic anterior lacrimal fossa combined with Collus's approach to the right nasal sinus tumor.According to the nasal endoscopic image, the tumor was totally removed and the surrounding normal tissue mucosa was extensively scraped to preserve part of the middle turbinates, skull base, orbital floor wall, and bone wall in the maxillary sinus.Due to the large cumulative range of Odontogenic myxoma tumors in this patient, we opted for conservative treatment .Because the segmental resection and reconstruction are more traumatic to the organism, and the patient is now only 20 years old, a female patient, we used a minimally invasive surgical approach as much as possible while ensuring a reduced risk of recurrence.
Eman Kheir et al. [17] Performed MRI was effective in displaying the true extension and contents of OMs.CT scans demonstrated the extensions of OMs, expansion, growth pattern, and rendered it possible to compare density of OM with that of surrounding muscles.On MRI, the walls of the tumors and patterns of the growth were clearly depicted.Although the tumors displayed predominantly a smooth wall, however in focal areas scalloping, crevices, budding, and/or lobulations were detected.These features supported the distinctive infiltrative nature of the tumor.Three months after surgery, we reviewed sinus CT, which showed no evidence of tumor growth.The same results were obtained with sinus MRI 9 months after surgery.

Conclusion
Odontogenic myxoma tumors are clinically treated with conservative and marginal surgery, both with low recurrence rates.However, conservative surgical treatments is less surgically invasive, more acceptable to patients, and own a better quality of survival.The clinical management of this case, as well as our comprehensive evaluation of the literature, could assist inform treatment decisions for odontogenic myxoma, with the goal of reducing the risk of recurrence while using a less intrusive surgical technique wherever possible.Although conservative and marginal surgery has proven effective, the risk of recurrence remains considerable and long-term follow-up is indispensable.More evidence of long-term outcomes after conservative surgery for OM is needed.5) and CT of the paranasal sinuses (Figure 6), and no clinical or imaging signs of recurrence were found.The patient's maxillofacial swelling and nasal congestion were significantly better than before (Figure 7).We will follow up on this case for a long time.

Figure 1 .
Figure 1.CT of the paranasal sinuses shows a large cystic hypodense lesion visible in the right maxilla, which projects upward and occupies the maxillary sinus to the point where the bone structure of the adjacent sinus wall is significantly thinned and obstructs the right nasal cavity inward, with a tooth visible on top.

Figure 2 .
Figure 2. MRI of sinus showed a soft tissue mass of about 5.2 cm Â 4.7 cm in size in the right maxillary sinus, septal sinus and middle and lower nasal passages, with low signal in T1WI and high signal in T2W.Enhancement scan: the mass showed significant heterogeneous 'brain gyrus-like' enhancement.

Figure 5 .
Figure 5.The nasal endoscopy A 45 endoscopic examination of the right anterior lacrimal saphenous fossa and the maxillary sinus at 3 months following surgery revealed excellent mucosal development and no indications of tumor growth.The right nasal cavity was still unobstructed.

Figure 6 .
Figure 6.The CT examination of the paranasal sinuses was repeated 3 months after surgery, showing enlargement of the right maxillary sinus cavity, thinning of the sinus wall, and absence of the medial wall part and middle turbinate, showing postoperative changes; no obstruction or narrowing of the nasal cavity was seen now.No recurrence was found in the paranasal sinus MRI at 9 months after surgery.

Figure 7 .
Figure 7. On the first postoperative day the patient showed swelling at the right nasolabial fold.And a postoperative image of the patient 3 months after the removal of the tumour.During the 3-month postoperative follow-up, this patient had a repeat nasal endoscopy (Figure5) and CT of the paranasal sinuses (Figure6), and no clinical or imaging signs of recurrence were found.The patient's maxillofacial swelling and nasal congestion were significantly better than before (Figure7).We will follow up on this case for a long time.