Recurrent and aggressive chondroblastoma of the pelvis with late malignant neoplastic changes.

A case of chondroblastoma involving the left ischium, lower wing of left ilium and inferior ramus of left pubis is presented. The tumor showed aggressive features and repeated recurrences over a 30-year period and ultimately developed the cytologic features of a malignant neoplasm. However, no metastases have developed.