Pigmented Villonodular Synovitis in Temporomandibular Joint: Image features and Differential Diagnosis

Pigmented villonodular synovitis in temporomandibular joint is an uncommon disorder. There are only 39 cases reported in the English literature. Here we report a case with this disease. The patient was a 52-year-old female suffering from progressive right pre-auricular pain and limitation in open mouth for 2 years. Physical examination revealed a palpable nodule in the right preauricular area. Computed tomography showed a peripherally enhancing nodular lesion adjacent to the neck of right mandibular condyle with bony erosion. Magnetic resonance imaging disclosed this nodular lesion slightly hyperintense on proton density-weighted images and hypointense mixed with some hyperintense regions and some foci of dark signal intensity on T2-weighted images. Peripheral enhancement on Gadolinium-enhanced T1-weighted images was also noted. Surgical excision was performed and pathology confirmed the diagnosis of pigmented villonodular synovitis. Even though pigmented villonodular synovitis in temporomandibular joint is a rare condition, it should be included in differential diagnoses for patients with pre-auricular painful nodule. Pigmented villonodular synovitis (PVNS) is a benign, locally invasive disorder of the synovium which was initially reported by Jaffe et al. [1] in 1941 to describe a yellow-brown tumor-like tenosynovial lesion. The yellow-brown pigmentation is caused by excessive deposits of lipid and hemosiderin. PVNS can be classif ied into diffuse or localized forms. When the entire synovium is replaced by a villous mass, it is referred to as diffuse PVNS. When the involvement is limited or focal, it is termed localized PVNS [2]. The knee joint is most commonly affected. Other joints including the hip, ankle, wrist, elbow and shoulder are also possible affected sites [3]. Temporomandibular joint (TMJ) involvement is rare; only 39 cases have been reported in the English literature. We further present a 52-year-old female who suffered from pre-auricular tenderness and palpable nodule. Surgical excision was performed and pathology confirmed the diagnosis of PVNS in TMJ. We also discuss its computed tomography (CT), magnetic resonance imaging (MRI) features and differential diagnosis.