With reference to the literature, this case report describes the presentation, investigation and management of a rare synovial cyst of the temporomandibular joint (TMJ), presenting as a painful preauricular swelling in a 33-year-old woman. Long term follow up of this patient is also discussed.

Synovial cysts of the temporomandibular joint (TMJ) are rare. An English language literature search found only 11 previously reported cases from 1978 to 2011. This presentation reviews the current understanding of TMJ synovial cysts and presents a new case report of a unilateral cyst, with particular note of the value of MRI scanning.

TMJ synovial cysts need to be differentiated from other pathology that may present similarly. Imaging studies are usually the key to diagnosis. Synovial cysts are distinguished from ganglion cysts predominantly on histopathology. Preauricular swelling from a TMJ synovial cyst may suggest a parotid lesion clinically, but the synovial cyst is palpable over the lateral pole of the mandibular condyle, may decrease in size on mouth opening, and may be associated with TMJ clicking or crepitus

Although synovial cysts of the TMJ are rare, they should be considered in any case of preauricular swelling with associated TMJ symptoms.