Journal of Oral and Maxillofacial Radiology

CASE REPORT
Year
: 2020  |  Volume : 8  |  Issue : 1  |  Page : 16--20

Imaging of osteochondroma of the temporomandibular joint – Report of two cases


Ruchi Gupta1, Sailesh Kumar Mukul2, Abhishek Singh2, Subhash Kumar3,  
1 Department of Radiodiagnosis, IGIMS, Patna, Bihar, India
2 Department of Dentistry, AIIMS, Patna, Bihar, India
3 Department of Radiodiagnosis, AIIMS, Patna, Bihar, India

Correspondence Address:
Ruchi Gupta
Flat Number 2014, Ganga 4, Jalalpur City, Gola Road, Danapur, Patna - 801 507, Bihar
India

Abstract

Osteochondroma of mandibular condyle is an uncommon entity. In the temporomandibular region, they usually present as restriction in mouth opening and pain in the joint. They can grow to a large size to impinge upon the cranial fossa. We present the imaging features of two such rare cases, one was giant condylar osteochondroma and the other one was condylar osteochondroma associated with contralateral osteochondroma of the zygomatic process of the temporal bone and congenital block cervical vertebrae. Computed tomography, magnetic resonance imaging of the temporomandibular joint and bone scan findings are discussed in detail along with the follow-up of patients.



How to cite this article:
Gupta R, Mukul SK, Singh A, Kumar S. Imaging of osteochondroma of the temporomandibular joint – Report of two cases.J Oral Maxillofac Radiol 2020;8:16-20


How to cite this URL:
Gupta R, Mukul SK, Singh A, Kumar S. Imaging of osteochondroma of the temporomandibular joint – Report of two cases. J Oral Maxillofac Radiol [serial online] 2020 [cited 2020 Aug 3 ];8:16-20
Available from: http://www.joomr.org/text.asp?2020/8/1/16/288834


Full Text



 Introduction



Osteochondroma is the most common benign tumor or tumor-like lesion of the bone.[1] However, they are uncommon tumors in the maxillofacial region with an incidence of 1% of all cases.[2] Less than three hundred cases have been reported so far.[3] Osteochondroma contains cortical and medullary bone with the overlying hyaline cartilage cap and shows continuity with the cortex and medulla of the subjacent bone. These can occur as solitary lesions or be multiple, latter are usually associated with hereditary multiple exostosis.[1] Imaging findings on computed tomography (CT), magnetic resonance imaging (MRI), and nuclear scan have been discussed in two cases, all of which have never been discussed together before.

 Case Reports



Case 1

A 26-year-old male presented with chief complaints of pain anterior to the tragus of the left ear in the temporomandibular joint (TMJ) along with burning sensation over the overlying skin for the past 4 years. There was history of deviation of the mouth to the right side, difficulty in chewing, and opening of mouth for 1 year. No other systemic complaints were present. On examination, bony hard swelling was seen in the left preauricular region. Rest of the body examination was within the normal limits. All routine blood tests were in the normal range. Based on clinical history and examination, differentials of TMJ bony ankylosis, condylar hyperplasia, and bony tumor were considered as these can lead to chin deviation as well as may present as bony hard swelling in the TMJ region. The patient was advised orthopantomogram for the evaluation of bony hard swelling. Panorex image showed a radiopaque lesion in the left condylar head region with sclerotic margins, and the condyle was not seen separately from the lesion [Figure 1]. Subsequently, CT revealed the presence of bony outgrowth from the left condylar head with medulla and cortex contiguous with the condyle. The lesion measured 3 cm × 2 cm in size. The bony outgrowth was seen medial to the condyle and pointing upward causing marked thinning and remodeling of the floor of middle cranial fossa and foramen ovale [Figure 2]. There was a cystic component of the lesion within the glenoid fossa. There was deviation of the chin to the opposite side [Figure 2]d. The bone scan revealed intense uptake of technician methyldiamine pertechnate (Tc99 MDP) in the left temporomandibular region to suggest osteoblastic lesion. There was normal uptake in rest of the skeleton [Figure 3]. Diagnosis of left condylar giant osteochondroma was made. The surgery was planned with the following objectives to address: (1) surgical removal of the lesion through complete excision, (2) correction of occlusal changes (open and crossbite) due to growth of the lesion, and (3) correction of resulted facial deformity. Single-stage surgery was done for the excision of the lesion and correction of the facial deformity [Figure 4]a. On histopathological examination, peripheral fibrous periosteum covering the chondroid mass with chondrocytes, central bony trabeculae, and central fibrovascular stroma was seen [Figure 4]b. After 1-year follow-up, there was no recurrence of the lesion, and the patient had no significant complaints.{Figure 1}{Figure 2}{Figure 3}{Figure 4}

Case 2

A 22-year-old female presented with progressively increasing difficulty in mouth opening for the past 4–5 years. She was not able to chew or speak properly. On further asking for systemic complaints, the patient replied she had difficulty in bending neck since childhood. On clinical examination, bony swelling was palpable in the region of bilateral TMJs, which was fixed to the bone. There was no tenderness at the site of swelling. The patient was fairly built and had no other systemic complaints. Clinical differentials were bilateral TMJ bony ankylosis or bony tumor. Further imaging was done to confirm the diagnosis. CT revealed the presence of bony protrusion from the right mandibular condyle with medulla and cortex contiguous with that of the lesion, obliterating the sigmoid notch and projecting anterior, inferior, and lateral to sigmoid notch. The right condylar head was flattened with reduced TMJ space. There was another bony protrusion on the left side from the articular eminence part of the zygomatic arch just anterior to the mandibular condyle projecting over the sigmoid notch [Figure 5]. C2–C6 cervical vertebral bodies were fused along with their fused posterior elements to suggest block vertebrae.[Figure 5]d The posterior arch was not seen, and anterior arch rachischisis was seen [Figure 5]e. MRI revealed the absence of cartilage cap in both the lesions to suggest burnt out cartilage cap [Figure 6]. The final diagnosis of right mandibular osteochondroma with secondary degenerative changes, left zygomatic osteochondroma, and multiple cervical block vertebrae with atlas arch anomalies were made. Surgical removal of bilateral bony outgrowth and bilateral TMJ interpositional arthroplasty with temporalis muscle and bilateral intraoral distractor placement was done [Figure 7]. The patient has been kept on regular physiotherapy and follow-up.{Figure 5}{Figure 6}{Figure 7}

 Discussion



Osteochondroma is a developmental lesion rather than true neoplasm. Solitary osteochondroma constitutes about 20%–50% of all benign bone tumors and 10%–15% of all bone tumors.[1] These lesions result from the separation of fragment of epiphyseal growth plate cartilage that herniates through periosteal bone which surrounds the growth plate. This cartilage shows persistent growth with subsequent enchondral ossification leading to the formation of osseous bone with overlying cartilage cap projecting from the bony surface. Surgery, trauma, and irradiation are other etiological factors of osteochondroma.[1] The cartilage cap measures about 1–3 cm in young people while it may be a few millimeters thick or entirely absent leaving the bone exposed.[1] Osteochondroma is extremely rare in the maxillofacial region. In the maxillofacial region, coronoid process of the mandible is the most commonly involved. Other sites include the body of the mandible, maxilla, maxillary sinus, zygomatic arch, symphysis, and condyle of the mandible.[4],[5],[6],[7] The tumor is more common in the second decade of life in axial skeleton, whereas in the TMJ region, they are more common in the fourth-fifth decade of life.[2] However, there are case reports which mention the occurrence in early life, as in our cases, both presented in the third decade of life.[8] The rare occurrence of osteochondroma in this region may be because of the presence of fibrocartilage in the TMJ rather than the hyaline cartilage.[2]

The most common location is the medial side of the mandible, followed by the anterior side since the tension created by the lateral pterygoid muscle attachment induces the proliferation of cartilage cells.[3],[9] In our case 1, the location was medial, but in case 2, it was on the anterolateral side of the condyle. The common symptoms include facial asymmetry, localized mass, ipsilateral posterior open bite, contralateral crossbite, pain, and limitation of mouth opening.[5],[10] Pain is mainly due to the impingement on adjacent structures like nerves or fracture through the stalk, otherwise they are painless in nature.[11] Our case 1 is a giant osteochondroma measuring about 3 cm × 2 cm in size and directed superomedially, causing thinning and marked remodeling of the floor of the middle cranial fossa on the left side. Kaneda et al. also reported a case of giant osteochondroma of the mandibular condyle.[10] Karras et al. reported concurrent osteochondroma of the mandibular condyle and ipsilateral skull base which resulted in TMJ fibrous ankylosis.[7] The Case 2 which we reported included condylar osteochondroma with contralateral zygomatic arch osteochondroma and multiple cervical block vertebrae, which has never been reported before. The patient did not have similar lesions in other parts of the body.

Panoramic radiographs showed radiodense mass in the region of condyle, and the density increases as the cartilage cap calcifies with age. CT is valuable in revealing the character of the lesion, its continuity with the cortex and medulla of the condyle and relation with the surrounding structures. MRI helps in evaluating the thickness of the cartilage cap, and the presence of cartilage cap confirms the lesion to be osteochondroma.[3] The bone scan can add to the diagnosis by confirming the increased radiotracer uptake due to an increase in osteoblastic activity as in our case done by Tc99 MDP. Furthermore, whole-body single-photon emission CT rules out other osteochondromas in the skeleton.

The major differentials of osteochondroma are unilateral condylar hyperplasia and osteoma.[2] Condylar hyperplasia shows enlarged condylar process with longer neck on the affected side, whereas osteochondroma appears as exophytic bony growth from the bony surface.[8] Histologically, normal cartilage proliferation seen in condylar hyperplasia, whereas disordered cartilage proliferation seen in osteochondroma.[9] Furthermore, the presence of cartilage cap confirms osteochondroma, however cap may be absent in older individuals and get calcified.[2] Osteoma leads to lobular enlargement of the condyle. Histologically, the presence of dense cortical lamellar bone is diagnostic of osteoma.[4]

In the axial skeleton, 1% of solitary osteochondroma show malignant transformation. They most often cease growth after puberty; hence, progressive growth in later life may indicate sarcomatous change in long bones. However, in the maxillofacial region, they may show slow growth even after puberty.[5] The recurrence rate of overall osteochondroma has been mentioned nearly 2%, but it is even very less in the condylar region.[12] Hence, follow-up and thickness of cartilage cap is of utmost important factor to rule out malignant transformation. In Case 2, the cartilage cap was not seen on MRI. Both the patients got operated and have been kept on regular follow-up. There was no evidence of malignancy in either of the cases.

Overall prognosis depends on the complete excision of lesion.[12] The recommended treatment is usually condylectomy and reconstruction. The surgical approaches have been preauricular, submandibular, intraoral, and combined ones.[4] In our Case 1, the giant osteochondroma was reaching up to the skull base and causing thinning of the floor of middle cranial fossa and foramen ovale. The whole bony lesion was excised through combined preauricular and submandibular approach. The residual facial asymmetry was corrected through sliding genioplasty. After 1-year follow-up, there has been no recurrence of the lesion, whereas in Case 2, removal of bony outgrowth, bilateral TMJ interpositional arthroplasty with temporalis muscle, and bilateral intraoral distractor placement were done by the department of oral and maxillofacial surgery.

 Conclusion



Osteochondroma should be kept as differential diagnosis, although rare in cases of bony growth in the temporomandibular region. Radiological diagnosis is confirmatory but should be accompanied with histopathological examination to differentiate from osteoma and condylar hyperplasia and to rule out any malignant transformation. Follow-up is recommended as there have been few cases of recurrence reported in literature.

Acknowledgment

We would like to thank the CT and MRI technicians: Mr Sanjeev Kumar and Mr Ranjeet Kumar.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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