Myositis Ossificans Traumatica of the Temporal Muscle: a Case Report and Literature Review Emphasizing Radiographic Features on Computed Tomography and Magnetic Resonance Imaging

Abstract

Objectives: Heterotopic bone formation within a muscle is designated as 'myositis ossificans', and it is associated with multiple aetiologies, such as trauma, genetic predisposition, post-infection, or undetermined causes. When the disease develops as a result of a trauma, the myositis ossificans is classified as 'myositis ossificans traumatica'. In this case report, a case of myositis ossificans traumatica is described, emphasizing its imaging features. Additionally, a literature review of the imaging features of myositis ossificans is discussed. Material and Methods: A 60-year old male patient presented with restricted mouth opening and pain during mastication. Multislice computed tomography and magnetic resonance imaging examinations were conducted. Case reports in the literature of myositis ossificans were searched databases from August 1984 until April 2019 using the keyword 'masticatory muscles' combined with 'myositis'; 'inflammatory myositis'; infectious myositis'; 'inflammatory muscle diseases'; 'focal myositis' and 'proliferative myositis'. Data was summarised and evaluated according to a critical appraisal checklist for case reports. Results: Multislice computed tomography demonstrated an ectopic hyperdense area arising from the coronoid bone and within the temporal muscle. Magnetic resonance imaging demonstrated the same area with a hypointense signal. In the literature review, 53 myositis ossificans cases were identified, and 12 cases affecting the temporal muscle were found. Conclusions: The main imaging feature of myositis ossificans is the presence of a radiopaque, hyperdense or hypointense mass in the affected muscle, which is seen on multislice computed tomography and magnetic resonance imaging, respectively. The final diagnosis is through histopathological examination, although imaging can suggest the most likely diagnosis.

Myositis Ossificans Traumatica of the Temporal Muscle Treated by Bilateral Coronoidectomy and Aggressive Physiotherapy: A Case Report

“…In other cases, isolated or repeated trauma (including blows, traffic accidents, violence, work-related accidents, gunshots), alveolar nerve block, dental extractions, and infections are among the possible causes mentioned. 1,5,8,10,11,16 But in some cases, there is no history of trauma. 3,7,16,17 The vast majority of ossifying myositis occurs in lower muscles due to their lower location and their repetitive motion during mastication, making them more vulnerable to trauma.…”

“…3,7,16,17 The vast majority of ossifying myositis occurs in lower muscles due to their lower location and their repetitive motion during mastication, making them more vulnerable to trauma. 7,8,13,16 The medial pterygoid muscle is the most affected, followed by the masseter. 7,8 Though temporalis muscle is vulnerable to trauma like the masseter, less cases of MOT are observed in this group and the reason for this is still unknown.…”

“…3,9,10,16 There is also a higher incidence in men due to their more active lifestyle and probably that is the reason why they suffer more traumas. 8,13 Differential diagnoses of MOT include several diseases involving ossification and calcification processes like thrombosis, phlebolites, osteomyelitis, osteomas, osteochondromas, hemangiomas, nodular fasciitis, and neoplasms such as synovial sarcoma, soft tissue sarcoma, osteochondroma, osteosarcoma, rhabdomyosarcoma, and metastatic disease. 7,18 Malignant tumors of the temporal bone are rare, with an estimated incidence of about 0.8 to 1 per million inhabitants per year.…”

“…3,4 It is characterized by the heterotopic formation of mature lamellar bone in muscles or other soft tissues after a trauma, 1,5,6 which can vary from a simple mandibular nerve block to a more severe trauma involving bone fracture. [7][8][9] Although MOT in the craniofacial skeleton is relatively rare, 6,8,10 its cases have increased in recent years. 11 According to a recent literature review, from August 1984 to April 2019, only 53 cases of MOT were reported in English.…”

“…3,4 It is characterized by the heterotopic formation of mature lamellar bone in muscles or other soft tissues after a trauma, 1,5,6 which can vary from a simple mandibular nerve block to a more severe trauma involving bone fracture. 7 –9…”