Imaging of an unusually located aggressive osteoblastoma of the pelvis: a case report.

INTRODUCTION: We present a case of an aggressive osteoblastoma involving the posterior acetabular column and the ischium, which is very rare location for the tumor. CASE PRESENTATION: A 21-year-old man presented with a persistent pain on the left buttock which extended on the rear surface of the thigh and the front surface of the left hip. A plain radiograph, a CT and MRI examinations were performed. The tumor was radically excised and histologically it proved to be an aggressive osteoblastoma. CONCLUSIONS: Although aggressive osteoblastoma is a rare entity it should be considered in the differential diagnosis of bone tumors. Our purpose is to reveal the radiographic presentation of this rare tumor.