Case contributed by Irvine Sihlahla
Diagnosis certain


Left knee pain for 3 months. No fever or history of trauma.No raised septic markers

Patient Data

Age: 15 years
Gender: Male

Left femur and knee


Distal left femur epiphyseal lesion crossing the physis in a skeletally immature patient. Solitary well defined lucent lesion with a narrow zone of transition, sclerotic rim and not associated with a cortical breach, periosteal reaction or large soft tissue component or joint effusion.

MRI left knee


Well circumscribed distal femoral epiphyseal lesion abutting the articular surface. The lesion demonstrates hypointense signal on T1W, T2W and T2W fat-saturated sequences. Marked surrounding edema. 


The patient subsequently underwent resection of the lesion and an endoprosthesis inserted. Xray shows endoprosthesis in situ with surgical staples, cement and subcutaneous gas locules.

The patient subsequently underwent surgical resection which confirmed a pathological diagnosis of chondroblastoma.

Case Discussion

Differential diagnoses include giant cell tumor, osteomyelitis with Brodie's abscess, and clear cell chondrosarcoma. Treatment includes curettage and bone grafting. Local recurrence may occur and rarely may have pulmonary metastasis.

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