[Chondroblastoma and its differential diagnosis].

Chondroblastoma is one of the most well defined cartilaginous tumors of bone on imaging and pathological findings. However in practice, the pathologist is faced with diagnostic difficulties. The most recent features of the tumor are developed in the review: clinical findings, skeletal distribution, and above all, the results of the imaging study which has to be strictly correlated with histology for the diagnosis as well as for the differential diagnosis, location, osteolysis, matrix production, periosteal reactions, MRI studies. Histopathology of chondroblastoma is described: cellular component, architecture, and secondary changes. Usefulness of cytopathology is also stressed on smears or tumor imprints. Main findings of recent and various immunohistochemical stains are described and discussed as well. Ultrastructural and cytogenetic studies are summarized. Treatment, natural history, and prognosis of the tumor are developed. The three most important differential diagnoses are giant cell tumors, clear cell chondrosarcomas, and aneurysmal bone cysts.