<prompt> A 15 yr school going student complains of moderate amount of occasional pain and swelling over the right knee joint. X ray was done which shows a lesion in right femoral distal epiphysis is suggestive of:EnchondromaOsteochondromaOsteoclastomaChondroblastoma  <response>: Chondroblastoma and GCT are epiphyseal tumours. GCT occurs in 20-40th decade Chondroblastoma 8-16 years of age group . Mc site of chondroblastoma is epiphysis of the distal femur Xray - expansile, epiphyseal, slightly symmetrically expansile. Mimics synovitis CF - pain and swelling. Biopsy :- Chicken wire calcification Rx curettage with bone grafting or bone curettage. 