Osteochondroma of the temporomandibular joint is a rare condition that most frequently affects the mandibular condyle. Fixed osteochondroma originating from the glenoid fossa is extremely rare and a literature search identified only two reported cases. The cases of two additional patients in whom osteochondroma developed in the posterior part of the glenoid fossa leading to the sudden onset of chin deviation and malocclusion are reported herein. We conclude that osteochondroma of the glenoid fossa is a slow growing benign tumour with typical clinical and radiological features. It requires surgical treatment, comprising resection of the tumour. Recurrence appears unlikely.
Osteochondroma of the temporomandibular joint (TMJ) is a rare condition that most frequently affects the mandibular condyle. We have previously reported the surgical treatment of these cases. Fixed osteochondroma originating from the glenoid fossa is extremely rare and a literature search identified only two reported cases. We report two additional patients in whom osteochondroma developed in the posterior part of the glenoid fossa leading to the sudden onset of chin deviation and malocclusion.
Case 1 was a 55-year-old female referred to our clinic by a dentist. Two years earlier the patient had woken up one morning with slight pain in the left TMJ and an inability to bite together on the left side. As she also had a slight swelling over the left TMJ she received antibiotic treatment, after which the swelling disappeared. Because the lateral open bite on the left side remained unchanged after conservative management, the patient was referred to an oral and maxillofacial surgeon.
Clinical examination revealed a lateral open bite on the left side and a cross-bite on the right side. The chin was deviated 5 mm to the right. There was no pain in the TMJ or jaw muscles. Maximum opening between incisors was normal at 47 mm. A preoperative computed tomography (CT) scan with typical sagittal views of the left TMJ revealed a well-defined corticated bony outgrowth occupying the posterior part of the glenoid fossa ( Fig. 1 A ). The internal structure of the outgrowth had a normal trabecular appearance. The base of the outgrowth showed no demarcation from the temporal bone. The condyle was dislocated anteriorly and inferiorly. An adaptive remodelling of the posterior slope of the eminence was also noted. The radiographic features indicated an osteochondroma of the glenoid fossa. On the tentative diagnosis of a benign hard tissue tumour of the TMJ, the patient underwent surgery.
The left TMJ was exposed via a pre-auricular approach. After the capsule was opened, the posterior part of the superior compartment was examined and showed a bony exostosis of approximately 10 mm in length and 7 mm in width firmly attached to the roof of the glenoid fossa. The exostosis appeared to be covered by normal fibrocartilage. The exostosis was resected using a bur and the roof of the glenoid fossa smoothened. The disc showed marked degeneration with a perforation in the central part and was therefore excised. No interpositional graft was placed in the joint space. The wound was sutured in layers.
The postoperative period was uneventful with no complications. The histopathological diagnosis was somewhat vague, but indicated features associated with an osteochondroma. The patient was followed for 4 years. Clinical examination revealed the patient to be free of symptoms: no pain (0 on a 10-point visual analogue scale (VAS)) and no functional impairment (VAS 0). Maximum opening was 45 mm. Permanent symmetry of the chin was achieved after the operation. The occlusion on the left side was clearly improved. A follow-up radiographic examination was performed 15 months after surgery. This revealed a condyle with a normalized centred position in the glenoid fossa. A small osteophyte was seen anteriorly on the condyle ( Fig. 1 B).
Case 2 was an 83-year-old female referred to the clinic by a dentist. One year earlier she had woken up in the morning with pain in the right TMJ and altered occlusion, lacking contacts between the teeth on the right side ( Fig. 2 A ). Clinical examination revealed a chin deviation of about 5 mm to the left, a lateral open bite on the right side with a cross-bite on the left side, pain on palpation over the right TMJ, and crepitation. Maximum mouth opening was 26 mm, during which bilateral translation in the TMJ was noted. A preoperative cone beam CT (CBCT) scan revealed a bony outgrowth filling almost the entire glenoid fossa of the right TMJ ( Fig. 2 B). The outgrowth had its base in the temporal bone and it measured 14 mm × 20 mm × 19 mm. The anteriorly and inferiorly displaced condyle had an osteoarthritic appearance with flattening, irregularities of the cortical bone, and centrally a fairly prominent pseudocyst. Bone appositions were noted on the posterior part of the condyle. The joint space was clearly reduced. The tentative diagnosis was osteochondroma of the glenoid fossa of the right TMJ.
The patient was subjected to the same surgical procedure as case 1. After pre-auricular exposure of the joint followed by opening of the lateral capsule, a large bony neoplasm with its base in the glenoid fossa was found in the posterior part. The impression was of an osteochondroma similar to that of the first patient. The osteochondroma was resected with a bur and the glenoid fossa was smoothened ( Fig. 3 ). Only remnants of a disc were found in the periphery. A clear chronic inflammation was present. Some adhesions were excised and the wound was then sutured in layers.