Osteoblastoma of the coccyx. A report of two cases.

Osteoblastoma, defined as a benign bone tumor by Jaffe and Lichtenstein, together with osteoid osteoma and multifocal osteoblastoma, belongs to the osteoblastic tumors. Due to the variable features of this tumor, differential diagnosis comprises fibrous dysplasia, giant cell tumor, aneurysmal bone cyst and osteoid osteoma; histological analysis is the only way to obtain a definite answer about the tumor type. Occasionally differential diagnosis from aggressive osteoblastoma and osteosarcoma may be difficult. The history of symptoms is usually long and diagnosis may be difficult both clinically and histologically.