|Year : 2014 | Volume
| Issue : 1 | Page : 33-36
Peripheral osteoma of the angle of mandible
Nigel R Figueiredo1, Manoj Meena2, Ajit D Dinkar1, Sonam Malik1
1 Department of Oral Medicine and Radiology, Goa Dental College and Hospital, Bambolim, Goa, India
2 Department of Oral Medicine and Radiology, Rajasthan Dental College, Jaipur, Rajasthan, India
|Date of Web Publication||18-Feb-2015|
Nigel R Figueiredo
House No. 685, Santerxette, Aldona, Bardez - 403 508, Goa
Source of Support: None, Conflict of Interest: None
Osteomas are benign osseous neoplasms that show continuous but slow growth and are characterized by the proliferation of compact and/or cancellous bone. The exact cause is unknown, and they are usually considered to represent hamartomas or reactive lesions secondary to low-grade inflammation. They can be classified into central, peripheral or extra-skeletal types. Peripheral osteomas occur most frequently in the frontal and ethmoid sinuses, and jaw involvement is rare. They are usually asymptomatic and may be discovered during routine clinical and radiographic examination. Radiographically, peripheral osteomas appear as oval radiopaque well-circumscribed masses attached to the cortex by a broad base or a pedicle. This article describes a case of a peripheral osteoma of the right angle of the mandible in a 20-year-old male along with a literature review.
Keywords: Mandible, panoramic radiography, peripheral osteoma
|How to cite this article:|
Figueiredo NR, Meena M, Dinkar AD, Malik S. Peripheral osteoma of the angle of mandible. Int J Oral Health Sci 2014;4:33-6
| Introduction|| |
Osteomas are slow-growing, benign osteogenic lesions that are characterized by proliferation of compact and/or cancellous bone. They may be classified into three types: Peripheral (paraosteal, periosteal or exophytic - arising from the periosteum), central (develop from the endosteum) or extra-skeletal (in the soft tissue). 
The cause of these lesions is obscure; they may arise from the cartilage or from the embryonal periosteum.  Some investigators consider osteoma a true neoplasm and others classify it as a developmental anomaly. , The possibility of a reactive mechanism, triggered by trauma or infection, has also been suggested because peripheral osteomas are generally located on the lower border or buccal aspect of the mandible, which are areas susceptible to trauma. 
Osteomas are essentially restricted to the craniofacial skeleton and are rarely, if ever, diagnosed in the other bones.  Peripheral osteoma is a rare entity and most frequently arises in the paranasal sinuses. Jaw involvement is uncommon and most cases are asymptomatic. On radiographic examination, they appear as well-circumscribed radiopaque masses that are round or ovoid in shape.  Histologically, osteomas may be divided into two types: (a) Compact or "ivory" and (b) cancellous, trabecular or spongy. 
This paper describes a case of a peripheral osteoma of the right angle of mandible in a 20-year-old male, which was diagnosed in our institution.
| Case Report|| |
A 20-year-old male patient reported to our out-patient department with a chief complaint of an asymptomatic swelling in the posterior region of the right mandible since the last 2 years. The patient gave a history of a progressive increase in the size of the swelling. There was no history of any trauma to the area.
On extra-oral examination, a well-circumscribed swelling was seen over the right angle of the mandible measuring around 1.5 cm × 1 cm [Figure 1]. The overlying skin was normal with no evidence of any discharge. On palpation, the swelling was bony hard in consistency, non-tender, non-pulsatile and non-compressible, with no local rise in temperature. Intra-oral examination did not reveal any abnormality. No palpable lymphadenopathy was evident.
Panoramic radiography showed a well-defined, irregularly oval radiopaque mass with a lobulated surface attached to the inferior border of the mandible in the right angle of the mandible region. The internal structure was homogenously radiopaque [Figure 2]. A right lateral oblique view showed a well-circumscribed radioopacity attached to the right angle of the mandible [Figure 3].
|Figure 1: Extraoral photograph showing a swelling over the right angle of the mandible region|
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|Figure 2: Panoramic radiograph showing a well-defined, irregularly oval, radioopaque mass attached to the inferior border of the mandible in the right angle of the mandible region|
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|Figure 3: Right lateral oblique view showed a well-circumscribed radioopacity attached to the angle of the mandible|
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Hematological investigations carried out were within the normal range. Based on the clinical and radiographic features, a provisional diagnosis of a peripheral osteoma was made. The lesion was treated by surgical excision under general anesthesia [Figure 4] and [Figure 5]. Histopathological examination of the lesion revealed a dense mass of compact bone containing osteocytes and medullary spaces in a loose connective tissue with capillaries, which confirmed the diagnosis of an osteoma.
Post-operative healing was uneventful and the patient has been under regular follow-up for the past 2 years, with no evidence of any recurrence.
| Discussion|| |
Osteomas are benign osseous neoplasms that characteristically show a continuous but slow growth. Peripheral osteomas are more commonly found in the frontal and ethmoid sinuses as compared with the maxillary sinuses, and jaw involvement is less frequent. , Among the jaws, the mandible is more commonly involved than the maxilla. The most frequent sites affected in the mandible are the posterior body, followed by the condyle, angle, ascending ramus, coronoid process, anterior body and sigmoid notch. 
Osteomas can occur at any age, but are most frequently seen in individuals older than 40 years of age.  Some authors describe them as being more common in males,  while others state a female predilection. 
These lesions are slow-growing and the only symptom of a developing osteoma is asymmetry caused by a bony hard swelling on the jaw.  The swelling is usually painless, until its size or position interferes with function. Occasionally, lesions may be discovered on routine clinical and radiographic examination. Depending on their location and size, osteomas can cause facial deformity, bone pain and limitation or deviation of the mandible on opening.  Lesions arising in the paranasal sinuses may cause headache, sinusitis or ophthalmologic manifestations.  The present case was diagnosed in a 20-year old male who presented with an asymptomatic bony hard swelling over the right angle of the mandible. While our patient was of a younger age, the site and clinical features of the lesion were consistent with that described in the literature.
Peripheral osteomas, in most cases, are easy to recognize because of their classic radiographic appearance - they appear as oval, radiopaque, well-circumscribed lesions attached to the parent bone cortex by a broad base or pedicle.  The internal structure of the compact variant (ivory osteoma) appears homogenous and uniformly radiopaque while the cancellous type may show evidence of a trabecular pattern. The present case showed typical radiographical features of an osteoma and appeared as a homogenous radiopaque mass attached to the inferior border of the mandible in the right angle of the mandible region.
The differential diagnosis of these lesions includes exostosis, osteoblastoma and osteoid osteoma, late-stage central ossifying fibroma or complex odontoma. A peripheral osteoma can be distinguished from an exostosis on the basis of an accurate case history and clinical characteristics, but there are no histologic differences.  The major differentiating feature is that exostoses usually stop growing after puberty, while osteomas have the ability to continue their growth even during adulthood. Osteoblastomas and osteoid osteomas are more frequently painful and grow more rapidly than peripheral osteomas. Central ossifying fibroma usually has well-defined borders, and a thin, radiolucent line may separate it from the surrounding bone.  Complex odontomas occur within the bone, have a density greater than bone and are surrounded by a radiolucent rim.
Histologically, compact osteomas are composed of normal-appearing dense lamellar bone with a few small marrow spaces and minimal marrow tissue. Cancellous osteomas show trabeculae of bone with varying amounts of fatty hematopoietic marrow and loose connective tissue in large medullary spaces. 
The presence of osteomas may be a sign of Gardner's syndrome, which is characterized by multiple polyps of the large and small intestine (which have a strong predilection for malignant conversion), skeletal abnormalities (multiple osteomas/enostosis) and multiple impacted supernumerary teeth. , Because the osteomas often develop before the colorectal polyps, dentists can play an important role in the early recognition of this syndrome, which is very important in the prognosis of this condition.
Removal of an asymptomatic peripheral osteoma is not generally necessary. Small lesions that do not cause any functional or cosmetic problems can be kept under observation with periodic follow-up. Simple surgical excision is the commonly used modality of treatment for peripheral osteomas. Surgery consists of removing the lesion at the base where it enters the cortical bone.  In the case of mandibular peripheral osteomas, an intraoral approach is preferable to an extraoral approach mainly for cosmetic reasons.  An extraoral approach is however preferred for larger tumors that are located in the posterior mandible. Recurrence after resection is very rare and malignant transformation has not been reported in the literature.  In the present case, the patient asked for treatment of the lesion due to aesthetic purposes and hence the lesion was surgically excised using the intraoral approach.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]