Osteoid osteoma is a benign bone tumour with self-limiting growth potential occurring in any part of the body. Two rare cases of a pathologically proven osteoid osteoma invading the temporomandibular joint (TMJ) are reported herein. This article also reviews the cases of osteoid osteoma of the craniofacial complex reported in the English-language literature to date. Although the clinical presentation of osteoid osteoma in the jaw differs from that of osteoid osteoma in the more common locations, the radiographic features are similar. In both cases presented, computed tomography revealed a small round osseous lesion with sharp margins in the TMJ. Bone scintigraphy was performed in order to differentiate the lesions from other osseous lesions. Both patients underwent surgical excision of the lesion with immediate relief of the pain. The importance of early recognition of the clinical and imaging characteristics of an osteoid osteoma of the TMJ is emphasized, in order to prevent misdiagnosis and avoid discouraging therapies.
Osteoid osteoma is a benign osteogenic neoplasm, first described as a separate clinical entity by Jaffe in 1935 . Lichtenstein defined osteoid osteoma as a “small, oval or roundish tumor-like nidus composed of osteoid and trabeculae of newly formed bone deposited within a substratum of highly vascularized osteogenic connective tissue” . The aetiopathogenesis of this lesion remains obscure. In general, an osteoid osteoma is believed to be a neoplasm, but others have reported it as the outcome of a trauma or an inflammatory process . Although it remodels continuously with osteoblastic and osteoclastic activity, an osteoid osteoma is characterized by its limited growth potential and a nidus not exceeding 2 cm . The tumour can involve any bone, but the femur, tibia, and vertebrae are the most often involved . The bones of the craniofacial complex are rarely affected, and only a few cases of temporomandibular joint (TMJ) involvement have been reported .
The diagnosis is strongly suggested by clinical and radiological imaging and is confirmed by histopathological examination . The vast majority of patients complain of dull nocturnal pain, usually responsive to non-steroidal anti-inflammatory drugs (NSAIDs). Sudden swelling and stiffness can occur when the osteoid osteoma is affecting a joint . A typical radiographic finding is the nidus − a small, ovoid to round, well demarcated radiolucency surrounded by reactive sclerotic bone .
The treatment of osteoid osteoma depends on the clinical presentation: if the pain is not relieved by NSAIDs, more invasive procedures such as surgical excision or radiofrequency ablation of the nidus are needed. These procedures bring an immediate end to the pain, and recurrence only occurs as a result of an incomplete removal .
Two cases of osteoid osteoma of the TMJ are presented herein. Although this site of involvement is uncommon, the radiographic appearance of the osteoid osteoma was characteristic in both cases.
A healthy 56-year-old Caucasian woman was referred to the hospital with an acute, progressive, right-sided pre-auricular swelling and dull pain, which was initially relieved by NSAID intake. With disease progression, the pain was aggravating, typically during the night, and no longer responded to NSAIDs. She had been diagnosed with a TMJ disorder on the right side more than 3 years ago and had received occlusal splint therapy. Clinical examination revealed a non-erythematous, firm pre-auricular swelling (ca. 35 × 40 mm) that was extremely painful on palpation. TMJ range of motion showed adequate mouth opening, although with an absence of left lateral excursion ( Fig. 1 ). There were no signs of a salivary gland pathology. Panoramic radiography demonstrated bilateral degenerative signs in the TMJ, with extensive deformation of the right condyle ( Fig. 2 ). Computed tomography (CT) revealed an adjacent well-demarcated round dense spot and encircling sclerosis on the mandibular fossa of the temporal bone ( Fig. 3 a). The lesion was in close relation to the skull base ( Fig. 3 b). Magnetic resonance imaging (MRI) illustrated an extensive periosteal reaction of the mandibular ramus ( Fig. 3 c).