[Chondroblastoma of the temporal bone: a case report]

A 30-year-old male had been suffering from left temporalgia of six months duration and then developed left hearing disturbance. Craniogram and bone window CT revealed a well defined osteolytic lesion in the left temporal bone. CT scan showed an expansile heterogenous mass with calcification. Both T1 and T2 weighted MRI demonstrated a well lobulated mixed intensity mass, but no evidence of dural or intracranial invasion. The tumor exhibited homogenous enhancement on CT and MRI. Angiogram revealed a well marked staining supplied by the left middle meningeal and deep temporal arteries. Subtotal removal of the tumor was carried out with cranioplasty. Histologically, this tumor was composed of round or polygonal chondroblasts, scattered osteoclast-like giant cells with a foci of cartilage in the stroma. Many reports describe giant cell tumor can be differentiated by immunohistochemical demonstration of S100 protein. Although in our case, histological findings simulated those of eosinophilic granuloma, it was diagnosed as chondroblastoma because of the foci of cartilage in the stroma. Because this tumor is usually benign, recurrence of the tumor is rare after surgical resection. Post-operative irradiation has been reported to be effective in decreasing the recurrence of the tumor. But it should be carefully observed because of possible sarcomatous change in such tumors.