Chondroblastoma of the temporal bone: a clinicopathologic study of five cases.

Chondroblastoma is a rare benign bone tumor. It commonly affects the epiphysis of long bones during the second and third decades of life. Chondroblastoma of the temporal bone is extremely rare. We reviewed five cases of chondroblastoma arising in the temporal bone. Four cases were female and one was male. The ages ranged from 41 to 60 years (mean, 53.6 years). All cases involved the temporal bone. Three involved the left side and two the right. Chief complaints were long-standing localized pain and hearing difficulty. A sharply demarcated lobulated mass was the main radiological finding. Microscopic findings were those of chondroblastoma of usual locations. Two cases showed aneurysmal bone cyst-like areas. Immunohistochemical studies for CD34, CD99, S-100 protein and cytokeratin were performed. Tumor cells were diffusely positive for S-100 protein in three cases and weakly positive for cytokeratin in one case. CD34 and CD99 were negative in all cases. In summary, chondroblastoma of the temporal bone is rare and occurs in older age group than reported cases of chondroblastoma of the usual location in the literature.