Abstract
Osteochondromas are the most common benign bone tumor, most commonly found in the ends of long bones; however, they rarely involve facial bones, particularly the mandible. Osteochondromas involving the coronoid process have rarely been reported in the literature but pose a diagnostic dilemma. When large enough, osteochondromas of the mandibular coronoid process can form a joint with the zygomatic arch (Jacob’s disease). This pseudoarticulation results in restricted jaw motion, which can clinically be mistaken for temporomandibular joint dysfunction. We report a case of a 39-year-old man with chronic restricted jaw motion undiagnosed for several years.
1
Introduction
Osteochondroma, or osteocartilaginous exostosis, is a cartilage-capped exophytic lesion that arises from the cortex of a bone. It constitutes 20% to 50% of all benign tumors and 10% to 15% of all bone tumors .
Although osteochondroma is considered the most common tumor of skeletal bones, it is relatively uncommon in the jaw. The rare osteochondroma of the mandible occurs at the condyle or the tip of the coronoid process. This cartilage-capped growth accounts for 35.8% of benign bony tumors and for 8.5% of bony tumors overall .
Enlargement of the coronoid process of the mandible was first described by Langenbeck in 1853, and joint formation between the coronoid process and the zygoma was first described by Jacob in 1899 . The most consistent clinical feature of this condition is reduction in mouth opening.
A review of the literature reveals only 34 histologically proven cases of osteochondroma of the coronoid process of the mandible. The disease appears to involve males (73.5%) more often than females, with a mean age of 35 years . The treatment is surgical, with an intraoral approach being the most preferred among most reported cases. None of the reported cases showed a recurrence .
2
Case report
A 39-year-old white man complained of progressive limitation in mouth opening for approximately 3 years. The patient was treated for temporomandibular joint (TMJ) dysfunction, without improvement. Physical examination revealed no palpable mandibular mass or facial asymmetry. For several years, the patient had undergone several magnetic resonance imaging (MRI) of the TMJ, revealing degenerative changes of the articular disk bilaterally, without evidence of abnormal displacement.
After clinical complaints of maxillary sinus pressure and suspected sinus disease, computed tomography (CT) examination of the paranasal sinuses demonstrated a large mushroom-shaped exostosis arising from the left coronoid process. The lateral wall of the maxillary sinus was deformed and showed a medially oriented concavity ( Fig. 1 ). There was no significant anterior bowing of the zygoma, thus, resulting in no gross facial asymmetry. There was no evidence of bony destruction or erosion. The sagittal reformatted image demonstrated the relationship between the tumor and the zygomatic arch, resulting in a pseudoarticulation ( Fig. 2 ).
A preoperative radiologic diagnosis of coronoid osteochondroma was established, based on imaging characteristics. During the following month, the patient was referred to a head and neck surgeon. Using an intraoral approach, we endoscopically excised the coronoid mass and removed it from the masticator space.
Pathology revealed an osteochondroma, measuring 2.0 × 1.0 × 0.8 cm, with a cartilaginous cap measuring 0.3 cm in maximal thickness. Shortly after surgery, the patient reported much improved jaw motion and opening.
2
Case report
A 39-year-old white man complained of progressive limitation in mouth opening for approximately 3 years. The patient was treated for temporomandibular joint (TMJ) dysfunction, without improvement. Physical examination revealed no palpable mandibular mass or facial asymmetry. For several years, the patient had undergone several magnetic resonance imaging (MRI) of the TMJ, revealing degenerative changes of the articular disk bilaterally, without evidence of abnormal displacement.
After clinical complaints of maxillary sinus pressure and suspected sinus disease, computed tomography (CT) examination of the paranasal sinuses demonstrated a large mushroom-shaped exostosis arising from the left coronoid process. The lateral wall of the maxillary sinus was deformed and showed a medially oriented concavity ( Fig. 1 ). There was no significant anterior bowing of the zygoma, thus, resulting in no gross facial asymmetry. There was no evidence of bony destruction or erosion. The sagittal reformatted image demonstrated the relationship between the tumor and the zygomatic arch, resulting in a pseudoarticulation ( Fig. 2 ).
