Giant cell reparative granuloma in the temporal bone of the skull base: report of two cases.

Giant cell reparative granuloma (GCRG) in the temporal bone of the skull base is a very rare benign osteolytic lesion. Here, we report two cases that were initially misdiagnosed according to the patients' histories, clinical symptoms, and brain imaging prior to surgery. One case had a history of resection of a middle cranial fossa meningioma. The other case had a history of otitis media and mastoiditis. Pathological examination of the surgical specimens led to the diagnosis of GCRG for both cases. Both patients recovered well after surgical removal of the lesion without radiotherapy. Follow-up for 2 years indicated no recurrence of GCRG. These two cases support the hypothesis that repairing responses of bone tissue to either trauma or inflammation may underlie the pathogenesis of GCRG.