The radiograph of a 32 year old patient is shown below. The patient is asymptomatic and the lesion revealed in the radiograph is an accidental finding. The most likely diagnosis is:

Radiological signs: The lesion presents as a chance radiographic finding. It is a round or an ovoid (<3 cm) uniform radiolucency with a well-defined, usually corticated, margin. Stafne’s bone cavity is non-expansile and is found below the mandibular canal just anterior to the angle of the mandible. The location of Stafne’s bone cavity distinguishes it from odontogenic lesions, whose origin is within the alveolar bone.