|Year : 2020 | Volume
| Issue : 2 | Page : 111-116
Osseous choristoma of the mandibular buccal vestibule: A case report and review of the literature
Reema Alshawaf1, Ahmed Zahrani2
1 Department of Oral Medicine and Diagnostic Science, College of Dentistry, King Saud University, Riyadh, Saudi Arabia
2 Department of Oral and Maxillofacial Surgery, College of Dentistry, King Saud University, Riyadh, Saudi Arabia
|Date of Submission||03-Nov-2019|
|Date of Decision||27-Dec-2019|
|Date of Acceptance||17-Feb-2020|
|Date of Web Publication||21-May-2020|
Dr. Reema Alshawaf
Department of Oral Medicine and Diagnostic Sciences, College of Dentistry, King Saud University, Riyadh
Source of Support: None, Conflict of Interest: None
Osseous choristoma is a tumor-like growth of lamellar bone which is found in a location where the bone does not normally form. It rarely occurs in the mandibular buccal vestibule. These lesions are either developmental (arising from ectopic mesenchymal cells) or a consequence of trauma and chronic irritation. A 50-year-old male was presented for diagnostic evaluation and surgical management of a long-standing hard mass involving the buccal vestibular sulcus of the mandible. The lesion was clinically examined and radiographically investigated using panoramic, intraoral, and cone-beam computed tomography images. Surgical excision was considered the ideal treatment, and postoperative histopathological examination confirmed a diagnosis of osseous choristoma. There was no evidence of recurrence over a 2-year follow-up period. Osseous choristoma involving the mandibular buccal vestibule can be misdiagnosed as an osteoma because of its clinical presentation; however, the lesion is typically not attached to the underlying bone and can be easily separated from the surrounding tissues. The diagnosis is based on clinical and radiographic examinations and generally confirmed by histopathological analyses.
Keywords: Buccal vestibule, cone-beam computed tomography, mandible, osseous choristoma
|How to cite this article:|
Alshawaf R, Zahrani A. Osseous choristoma of the mandibular buccal vestibule: A case report and review of the literature. Saudi J Oral Sci 2020;7:111-6
|How to cite this URL:|
Alshawaf R, Zahrani A. Osseous choristoma of the mandibular buccal vestibule: A case report and review of the literature. Saudi J Oral Sci [serial online] 2020 [cited 2020 Sep 19];7:111-6. Available from: http://www.saudijos.org/text.asp?2020/7/2/111/284659
| Introduction|| |
A choristoma is a tumor-like mass of histologically normal tissue which has developed in an abnormal location.,, It is therefore, different from a hamartoma, which is a tumor-like mass of mature normal cells located where they are normally found. Choristomas have been reported under a variety of other terms according to the type of dislocated cells. However, many of the terms applied may be inappropriate; for example, “tumor” does not reflect the nonneoplastic clinical behavior and microscopic pattern, and “heterotopia” does not convey the appearance of a tumor like mass.”
While choristomas are considered rare, they can develop in the oral cavity as tumor-like masses of normal but heterotopic tissues, including bone, cartilage, the gastric mucosa, glial tissue, and sebaceous and salivary glands. Thus, they are named according to the tissue from which they are derived from. The most common type of oral choristoma is composed of bone, cartilage, or both. In 1971, Krolls et al. coined the term osseous choristoma for lingual osteoma, a lesion originally described by Monserrat in 1913 which is a tumor-like growth of lamellar bone in a location where the bone does not normally form.,
The etiology of osseous choristoma is based on two main theories. The developmental malformation theory proposes possible entrapment and further ossification of mesenchymal cell originated from embryonic branchial arches. This theory is widely accepted, and it explains the development of lingual choristoma. The other theory proposes reactive or posttraumatic metaplasia and calcification of the affected area. Conventionally, osseous choristoma is considered a developmental anomaly. Although it normally occurs in younger individuals, cases involving older patients and a wide range of age groups have been reported.,, Individuals in the third and fourth decades of life are reportedly the most commonly affected, and women are more susceptible than men. Intraoral osseous choristomas clinically present as slow-growing lesions of variable sizes that can be nodular, pedunculated, or sessile. The majority, if not all, are asymptomatic, although globus hystericus, dysphagia, nausea, and airway obstruction have been reported in association with large lesions, mostly lingual choristoma. The dorsal surface of the tongue is the most common site, followed by the buccal mucosa,,,, labial mucosa, gingiva and alveolar ridge,, sublingual and submandibular regions,, and ventral surface of the tongue. Because of the rarity of intraoral choristomas, clinical diagnosis can be challenging. Therefor, diagnosis should be based on clinical, radiographic examinations and confirmed by histopathological analyses. The differential diagnosis is based on the site and appearance of the lesion including the shape, internal consistency as well as the relationship to the surrounding structures. It should include all possible benign lesions that involve similar location and appearance.,
Osseous choristomas can be easily misdiagnosed as osteomas. An osteoma is a benign neoplasm of the bone that is associated with normal skeletal structures, unlike an osseous choristoma which is found in an abnormal site away from any normal osseous tissue.
Osteomas are attached to the cortex of the jaw by a pedicle or along a wide base. The mucosa covering the tumor is normal in color and freely movable.
Another rare lesion that could resemble a choristoma is an osteolipoma. However, histopathologically, it is composed mainly of abundant mature adipose tissue with no atypia and separated by thin fibrous connective tissue. Randomly distributed irregular trabeculae of immature bone exhibiting osteoblastic activity is usually seen throughout the tumor.
Other lesions involving bone formation or changes within the bone such as fibrous dysplasia and myositis ossificans have different radiographic and clinical features. Fibrous dysplasia results from a localized change in normal bone metabolism that results in the replacement of all the components of cancellous bone by fibrous tissue containing varying amounts of abnormal-appearing bone which occurs within the bone. Myositis ossificans involve heterotopic bone formation within the interstitial tissue of muscle and associated tendons and ligaments following trauma.
Histopathologically, osseous choristoma appears as a well-circumscribed mass of viable lamellar bone with haversian canals, with surrounding dense fibrous connective tissue covered by stratified squamous epithelium. Hematopoietic and fatty marrow activities are occasionally observed, whereas osteoblastic and osteoclastic activities are rarely present. Surgical excision is the only recommended treatment. Recurrence following surgical excision is rare.,
Here, we present a case involving a 50-year-old male who developed an osseous choristoma in the mandibular buccal vestibule. The purpose of this report is to present this rare case as it can provide valuable information for clinicians with regard to diagnosis and management and thus help improve the quality of the health care provided.
| Case Report|| |
The patient reported here provided written consent for publication of his data and images.
A 50-year-old Saudi male presented with a chief complaint of a bony, long-standing swelling in the lower right segment of the mandible. The swelling was asymptomatic since it was noted, and there was no history of discomfort in speech, mastication, or other daily activities. The patient was not aware of any trauma to the area, and no other complaints were reported. The medical and family histories were unremarkable, and the patient was generally in good health.
Clinical examination of the mandible revealed the presence a firm and nontender nodule adjacent to the buccal cortex and apical to teeth #46 in the buccal alveolar sulcus (buccal vestibule), the area between the alveolar process and buccal mucosa. The overlying mucosa was intact, appeared normal; the mass was free from the periosteum and not attached to any adjacent structures, such as the mandibular bone. The function of the sensory nerves in the mental region, cheek mucosa, and entire oral cavity was intact, and there were no palpable lymph nodes in the neck.
Panoramic and periapical radiographs showed generalized horizontal alveolar bone loss. A well-defined, corticated radiolucency with trabeculations was observed in association with the periapical region of the right first molar. The mass extended from the distal surface of the right second premolar to the right second molar and from the periapical area of the right first molar to just above the inferior dental canal. The first molar was coronally displaced and did not have an antagonist tooth [Figure 1] and [Figure 2].
|Figure 1: Panoramic radiograph shows the lesion as a well-defined round corticated mass related to the periapical area of tooth #46|
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|Figure 2: Periapical radiograph shows the lesion as a well-defined round corticated mass related to the periapical area of tooth #46|
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Cone-beam computed tomography examination of the maxillofacial region was performed to further investigate the exact location and relation of the lesion with the adjacent anatomical structures. Sectional images were obtained in multiple planes. A round, well-defined mass appearing more radio dense than the surrounding soft tissues was observed [Figure 3] and [Figure 4]. It showed a trabecular pattern that was slightly hypodense relative to the adjacent trabecular bone. The location was within the soft tissues adjacent to the buccal cortical plate of the right first molar, with the plate exhibiting thinning and depression [Figure 5].
|Figure 3: Cone-beam computed tomography axial section shows the relation of the mass to the buccal cortical plate. It causes thinning and depression in the adjacent buccal cortical bone|
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|Figure 4: Cone-beam computed tomography coronal section shows the relation of the mass to the buccal cortical plate. It causes thinning and depression in the adjacent buccal cortical bone|
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|Figure 5: Cone-beam computed tomography three-dimensional image shows the relation of the mass to the buccal cortical plate. It causes thinning and depression in the adjacent buccal cortical bone|
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The radiographic features suggested a bone-like mass within the soft tissue (soft tissue osteoma). The location of the boney mass within the soft tissues, and the fact that the mass was not attached to any adjacent structures such as the mandible helped in excluding other possible boney lesions.
The lesion was surgically excised from the buccal mucosa via an intraoral approach using sharp and blunt dissection under local anesthesia [Figure 6]. The specimen measured 1.1 cm × 1.4 cm × 0.9 cm and was spherical with a smooth surface and pinkish color [Figure 7]. It was stored in 10% formaldehyde and sent for decalcification and histopathological examination. Hematoxylin and eosin staining revealed. the presence of a well-circumscribed mass composed of adipose tissue surrounded by mature bone and separated by thin trabecular bony septa (viable lamellar bony trabeculae) [Figure 8]. A diagnosis of osseous choristoma (soft tissue cancellous osteoma) was established on the basis of the pathology report.
The patient's postoperative recovery was uneventful, and regular follow-up studies over 2 years showed no evidence of recurrence.
| Discussion|| |
Intraoral osseous choristoma has been reported to occur in several locations, although lesions involving the buccal mucosa are relatively uncommon and considered rare when compared with lesions involving the tongue. The English literature has documented 18 cases of osseous choristoma involving the buccal mucosa. Six of these cases, including the present case, showed lesions in the buccal alveolar sulcus or vestibule [Table 1]. In our case, the osseous choristoma was located in the mandibular buccal vestibule in the area between the buccal cortical plated of the alveolar process and the buccal mucosa. Therefore, it was considered to be among those found in the buccal mucosas.,,, The lesion was accessed and removed from the buccal mucosa as well. The mean patient age was 57 years (range: 42–75 years), which is within the same age range of the patient 50 years in this case. No male or female predominance (three women and three men) was seen in the reported of oral buccal osseous choristomas.,,, The lesions were present for 1–10 years, with a duration of 40 years in one case. They measured an average of 2 cm and presented as firm mass located lateral to the body of the mandible, which is similar to our findings [Table 1]. The longer duration of the lesions in some cases could be explained by features such as slow growth, lack of symptoms, and patient's lack of awareness. Accordingly, late diagnosis could be a reason for the detection of this lesion in older patients.
|Table 1: Reported cases of Buccal oral osseous choristoma in the English literature|
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Although the etiology of osseous choristoma remains uncertain, lesions involving the buccal mucosa may initially arise as reactive or posttraumatic abnormalities.,, Some studies have linked the recurrences of osseous choristoma at the site of previously excised lesion to new fibrotic ossification and subsequent ossification of hematoma.,,
The radiographic features suggested a soft tissue osteoma. However, the term Ossoues Choristoma is a more acknowledged term, which was first described by Krolls et al. It helps distinguish it from an osteoma which is a benign neoplasm.
An osteoma is a benign neoplasm of bone that is associated with normal skeletal structures, unlike an osseous choristoma which is found in an abnormal site away from any normal osseous tissue. In our present case, this site was the patient's mandibular right buccal vestibule.
Histologically, osteomas appear as dense compact bone with infrequent marrow spaces or trabecular bone with marrow spaces containing fibrous and fatty tissue, but are closely associated with a normal skeletal structure., An osseous choristoma is a tumor-like growth of histologically normal tissue in an abnormal location not in connection to normal skeletal bone., Therefore, the diagnosis of osteoma was excluded.
Another rare lesion that could resemble a choristoma is an osteolipoma. However, histopathologically, it is composed mainly of abundant manure adipose tissue with no atypia and separated by thin fibrous connective. Randomly distributed irregular trabeculae of immature bone exhibiting osteoblastic activity are usually found throughout the tumor. Both osseous choristomas and osteolipoma are benign connective tissue lesions, which are treated by conservative surgical excision and exhibit similar prognoses.
In our case, the location of the boney mass within the soft tissues as well as the fact that the mass was not attached to any adjacent structures such as the mandible helped in excluding other possible boney lesions. For example, Fibrous dysplasia results from a localized change in normal bone metabolism that results in the replacement of all the components of cancellous bone by fibrous tissue containing varying amounts of abnormal-appearing bone which occurs within the bone  In our case, the boney lesion was peripheral located within the adjacent soft tissue. In addition, myositis ossificans involve heterotopic bone formation within the interstitial tissue of muscle and associated tendons and ligaments following trauma  In our case, this was excluded because of the location is not within a muscle or tendon and absence of history of trauma.
Histopathological investigation is needed for the confirmation of the diagnosis.
Surgical excision is the only recommended treatment. Recurrence following surgical excision is rare, with only three reported cases. Gregoire et al. reported one case of recurrent osseous choristoma in the mandibular buccal vestibule; the remaining two cases involved lesions in the masseter muscle and retromolar area, respectively.
| Conclusion|| |
We reported a rare case of osseous choristoma of the mandibular buccal vestibule in a 50-year-old male.
Although osseous choristoma is a very rare entity in the oral cavity, it should be considered when a patient presents with a peripheral lesion not attached to underlying bone that has a hard consistency on palpation. Diagnosis is based on clinical, radiographic examinations and confirmed by histopathological analysis. Surgical excision is the recommended treatment. Recurrences have been rarely reported.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
We like to acknowledge King Saud University. College of Dentistry in which the patient was seen examined and managed. We also extend our acknowledgment to Oral Pathologist Dr. Ahmed Qannam from the Department of Oral Medicine and Diagnostic Sciences at King Saud University College of Dentistry for his efforts in the histopathological examination of the biopsy for this case.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8]