A comparative study of simple bone cysts of the jaw and extracranial bones.

OBJECTIVES To improve the interpretation of simple bone cyst (SBC) lesions of the jaw. METHODS A comparative study of SBC lesions of the jaw and extracranial bones was performed through a literature survey. RESULTS In extracranial SBC, the cavities were always filled with fluid, and a high recurrence rate was shown through extensive research. Aneurysmal bone cyst (ABC) was included in the differential diagnosis owing to some clinicopathologic similarities. Fluid, gas and blood were found in the cavity in jawbone SBC, and recurrence was believed to be rare. Differential diagnosis was rarely discussed in the literature. CONCLUSIONS Based on reports, the cavity did not normally contain gas because no air-fluid level was observed on panoramic radiographs and no density/intensity area indicating gas was seen on CT or MRI. A blood-filled cavity should be examined carefully, and the possibility of an ABC should be considered. The recurrence rate needs to be re-estimated because an extensive survey has not been performed to clarify the treatment outcomes of jawbone SBC.