14 year old young male present with Pain in the knee joint with no history of trauma. X-ray revealed an ill defined lucency in the tibial epiphysis.
MRI shows a relatively, well defined, regular , heterogeneously altered signal intensity, space occupying lesion involving tibial epiphysis including the spines with extension across the physis into the metaphysis with peripheral low signal on all sequences with extensive perilesional oedema and heterogeneous enhancement – Chondroblastoma is likely.
Teaching points by Dr MGK Murthy, Scan by: Mr Abdul Hamid.
- A, rare, benign, cartilaginous tumor of the epiphysis of the growing skeleton.
- Signal intensity reflex the cellularity with lower than normal marrow on T1, low / high signal on T2 fat suppression.
- Extension into the metadiaphysis is uncommon ( 60%), in which case could mimic chondromyxoid fibroma / GCT.
- Perilesional oedema is usually extensive mimicking and aggressive lesion particularly clear cell chondrosarcoma or GCT.
- 72% occur in lower limb with 18% in the tibia.
- T2 low signal is attributed to abundance of immature chondroid matrix / chondroblastic hypercellularity / calcification / haemosiderin.