Fibrosarcoma of the temporomandibular joint area: benefits of magnetic resonance imaging and computed tomography

Abstract

Here, we report a case of primary fibrosarcoma in the mandible of a 33-year-old woman with symptoms and radiologic signs mimicking temporomandibular disorder. We also present a literature review of fibrosarcomas in the jaw. CASE REPORT A 33-year-old woman presented with a 1-year history of trismus associated with a clicking noise in the left temporomandibular joint (TMJ). Her chin shifted to the right side when she opened her mouth (Figure 1). Panoramic radiographs (Figure 2, A, B) and magnetic resonance imaging (MRI) scans (Figure 3, A-H) of the TMJ regions showed signs of temporomandibular disorder (TMD), so conventional treatment for TMD was prescribed, including occlusal splints, mouth-opening exercises, and a muscle relaxant for 6 months. When the MRI scout images were analyzed retrospectively, the findings of 2 of 5 scout images were suggestive of tumor (see Figure 3, A, E). The patient was referred again 6 months after the initial visit for investigation of insomnia caused by spontaneous pain in the left TMJ area. She also had paralysis of the lower lip and left chin. She had herpes labialis and gastroenteritis caused by stress. Given the suspicion of malignancy, both MRI and computed tomography (CT) were performed. MRI showed a round, inhomogeneous mass in the pterygomandibular portion of the masticator space, which caused minimal medial narrowing of the left parapharyngeal space (Figure 4, A, B). CT found significant bony erosion of the inner cortex of the left ramus of the mandible (Figure 5). The patient was referred to another hospital for further management because the tumor grew toward the pharyngeal arches. An incisional biopsy was subsequently performed, and the initial diagnosis was a sarcoma based on the histopathologic examination of the biopsy. A definitive histologic diagnosis was reached by exclusion. The tumor was diagnosed as a grade 3 (poorly differentiated) fibrosarcoma using the FNCLCC (Federation Nationale des Centres de Lutte Contre le Cancer) grading system. Histopathologic examination found that the tumor contained spindle cells arranged in compact fascicles that were intersected by various amounts of delicate thin to dense keloid-like collagen. Cell bundles were arranged at acute angles to each other, whereas the presence of fascicles was subtler in other areas. A prominent storiform pattern was not seen (Figure 6). The fibrosarcoma was resected followed by postoperative radiotherapy and chemotherapy. The tumor was removed, along with the left ramus of the mandible, a portion of the left maxilla, a deep part of the parotid gland, and lymph nodes located superior to the omohyoid muscle. The cheek mucosa was reconstructed using a free anterolateral thigh flap (Figure 7). The patient recovered and got married afterward; however, lung metastasis with Fig. 1. Facial photograph. The patient’s chin shifted to the right side when she opened her mouth.