Mandibular Myofibroma and Severe Trismus: A Complex Case and Review of Complications

A female child was investigated for insidious onset of temporomandibular joint dysfunction and trismus in the setting of a mandibular myofibroma. Myofibromas, benign mesenchymal neoplasms composed of spindle cells, are rarely found in the oral cavity, most commonly in the mandible. These lesions are historically described as indolent with a high cure rate and minimal recurrence rates following surgical resection. The patient initially presented with concerns regarding snoring, retrognathia, and jaw ankylosis, as well as a history of trouble latching as an infant but without obvious physical deformities. Imaging revealed a large expansile lytic mass of the mandible, but no temporomandibular joint involvement; surgical biopsy evidenced myofibroma, and the lesion was resected. Over the course of disease, the lesion continued to expand, and the patient's maximal incisal opening continued to decrease despite conservative management with jaw physiotherapy; eventually she could not open her mouth despite the absence of joint involvement. Re-exploration along with formal jaw physiotherapy was achieved and optimal jaw opening was maintained. Myofibromas are rare benign desmoid tumors that can present anywhere in the body in solitary and multicentric forms, and previously did not present significant challenges to surgical and medical management. Tumors of the mandible may present with trismus and soft tissue ankylosis, which can mimic temporomandibular joint dysfunction in the absence of joint involvement. Physical therapy, rehabilitation, and soft tissue contracture release are key to management and improving outcomes in oral cancer patients, regardless of tumor pathology.