Chondroblastoma

16 y/o female who presented with long-standing pain in the knee region. Radiographs of left knee joint in AP and lateral projections were taken. A well defined mildly expansile lytic lesion is seen involving fibular head epiphysis. The lesion shows narrow zone of transition and peripheral rim of chondroid matrix and central septations. Chondroblastomas typically occur in the epiphyseal regions and most commonly arise in the ends of major tubular bones. They can also occur in any center of ossification such as the greater trochanter. Pain is the presenting symptom in almost 90% of cases. Case produced with permission, courtesy of Dr. Frank Gaillard. Radiopaedia. Complete case is here.