Introduction
Odontogenic keratocyst is the most aggressive odontogenic cyst in the oral cavity. It is a significant clinical entity due to rapid growth and tendency for recurrence and extension into adjacent tissues including bone, which is typically occurring in the mandible and maxilla. In this study we present a case of odontogenic keratocyst which is unusually originated from temporomandibular joint.
 Case Report
67-year-old female presented to our clinic for the evaluation of an enlarging mass in the left temporal region and discomfort at the temporomandibular joint during mouth opening. Maximal mouth opening was about one centimeter. She gave a history of undergoing surgery for three times for the same reason and the pathological diagnosis was odontogenic keratocyst. Clinical examination revealed a firm mass measuring 4 cm diameter and involving the left fossa temporalis and extending to the left temporomandibular joint. A cystic lesion 4.5 x 2.1 cm in size was detected in computerized tomography scanning. During the procedure, the lesion was found to be originated from the temporomandibular joint, which was the cause of the joint movement restriction. The pathological diagnosis was odontogenic keratocyst. The patient is at the first year of follow-up without any problem. Maximal mouth opening is about 4.5 centimeters.

 Discussion
Odontogenic keratocyst is reported 70.16% in the mandible, 12.35% in the maxilla, 12.82% in the soft tissues and 4.66% in the maxillary sinuses. We did not found any report in such location of odontogenic keratocyst in the literature. They are known to have high recurrence rate ranging between 5 to 62%. Recurrence usually manifests itself within the first 5 to 10 years; however previous publications have reported recurrence as long as 41 years after treatment. Due to possible recurrences many years after initial treatment, a life-long follow-up schedule is suggested, regardless of the treatment given – every year for the first 5 years and every 2 years thereafter.